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UBC Theses and Dissertations

A general study of the primary and secondary productivity of the northern Pitt meadows with special reference… Barnard, Anthony Erwin 1975

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A GENERAL STUDY OF THE PRIMARY AND SECONDARY PRODUCTIVITY OF THE NORTHERN PITT MEADOWS WITH SPECIAL REFERENCE TO THEIR USE BY WATERFOWL by ANTHONY ERWIN BARNARD A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE : in the Department of PLANT SCIENCE We accept th is thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l ,1975 In presenting t h i s t h e s i s in p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f or reference and study. I f u r t h e r agree that permission for extensive copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s rep r e s e n t a t i v e s . It i s understood that copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my w r i t t e n permission. Depa rtment The U n i v e r s i t y of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 \J ABSTRACT . • The lowlands' of the study area consist of nearly 4,600 acres of developed and undeveloped farmlands and approximate Iy 3,100 acres of freshwater marsh and associated wildlands and bogs. At present the latter areas attract, a wide range of recreation ' oriented activities. In addition, the marshes were believed to play an integral part in waterfowl utilization of the. Lower Fraser Valley. The basic objectives of the study were to delineate, various indices of biological, production, particularly as they pertained to waterfowl, between habitats within the study area and between the study area as a whole and wetlands elsewhere. To this end, the importance of cover in influencing faunal distribution was recognized and schematically presented in a cover-map. Basic characteristics of soils subjected to varying hydric conditions were described. The quality of waters in the different habitats appeared to refIect current land. use. In this respect, waters of the marshes, wildlands, bogs and large tracts of undeveloped farmlands were oligotrophic in nature. Conversely, waters in and adjacent to actively farmed areas were relatively eutrophic. The water regime of the lands subjected to pumping is fairIy.stab Ie whereas in the.unpumped habi-tats wide fluctuations in water level occur bi-annually. Yields of major plant communities were monitored throughout the grow-ing season, thus indicating primary production capabilities of the area. In the unpumped habitats a large proportion of the nitrogen per unit area of vegetation is "tied up" in accumulations of old growth and duff. In both pumped and unpumped habitats, hardhack communities were shown to account for much of the nutrient "short-stopping" in the study area. Secondary succession is in effect in both pumped and unpumped habitats and vegetation development suggests long-term development towards peat bog in many areas. In terms of both total invertebrate yield and yield of twelve fami-lies considered potential Iy important to young waterfowl, the Ag. II / habitat is more productive than Ag. I or the Sturgeon Slough marsh. Based on brood and invertebrate production in Ag. I, feed for ducklings is not a factor in. low brood production in Ag. II but may contribute to that currently experienced in the Sturgeon Slough marsh. The major nesting species of waterfowI"were mallard,.cinnamon teal and wood duck. Twenty-four broods were actually censused in 1972 and twenty in 1973. Calculation of brood production based on breeding pairs and estimates on areas too large to census indicated seventy-eight broods were raised in the habitats investigated in 1973. For the entire study area, production was be 8.3 broods/sq. mile in 1973. Rapid increases in water level during May and June conflict with the nesting period of both mallard and teal in the unpumped habitats, and probably are a major factor in current levels of brood production in these areas. Marshes of. the unpumped habitats were extensively used by moulting mallards and.wood duck and may serve the moulting needs of most summer resident waterfowl in the Lower Fraser Valley. Harvest of most local mallards occurs predominantly in or adjacent'.to their natal area. Adult wood ducks are apparently non-migratory and undergo litt l e pressure after the first two weeks of hunting. Approximately one-third of the immature wood duck harvest occurs in their natal area, gener-al ly by late October. The remaining harvest is distributed between the' - IV r-Wi Ilamette . VaI ley of Oregon and the Central Valley of California and generally occurs during late November and December. Less than 10$ of the study area is available for public hunting resulting in a dispropor-tionate hunting effort and success rate. Fall and winter waterfowl use has apparent Iy declined considerably in the last twenty years. Control and regulation of the water, regime in the unpumped habitats-must be realized before proper management of these lands for waterfowl can be realized. Immediate management opportunities do exist, however, for 'increasing the breeding population of wood duck in the study area. It is strongly recommended that only controlled hunting be permitted in •the unpumped habitats if maximum year round- production of waterfowl is the management objective in these areas. ' . TABLE OF CONTENTS TITLE PAGE ABSTRACT TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES 1.0.0 INTRODUCTION .1.1.0 C o n v e r s i o n T a b l e s f o r B r i t i s h and M e t r i c Weights and Measures 2.0.0 ACKNOWLEDGEMENTS • 3.0.0 STUDY AREA DESCRIPTION 3.1.0 L o c a t i o n and P h y s i o g r a p h y 3.2.0 H i s t o r y 3.3.0 C l i m a t e 3.4.0 S o i l s 3.5.0 S o c i o - e c o n o m i c F a c t o r s 4.0.0 VEGETATION, SOILS AND WATER 4.1.0 M a t e r i a Is and Methods 4.1.1 V e g e t a t i o n Cover Map 4.1.2 Sampl ing of. V e g e t a t i o n 4.1.3 Chemical A n a l y s i s of V e g e t a t i o n (a) T e r r e s t r i a l and. Emergent '(b) A q u a t i c 4.1.4 Co I I e c t ion and C h e m i c a l A n a l y s i s of Water 4.1.5 Co 1 1 e c t ion and Chem i c a I A n a l y s i s o f So M s 4.2.0 R e s u l t s and O b s e r v a t i o n s 4.2.1 Cover Map 4.2.2 Dry M a t t e r Y i e l d s and N u t r i t i v e Q u a l i t y of S e l e c t e d T e r r e s t r i a l and A q u a t i c • P l a n t Communities 4.2.3 Water Regime and Q u a l i t y 4.2.4 S o i l C h a r a c t e r i s t i c s - v i -Page. 4.3.0; 'D i s c u s s ion 50. 4.3..I Cover Map 50. 4.3.2 Water Regime - P a s t and P r e s e n t 50. 4.3.3 Water Qual i t y 56. 4.3.4 S o i l T e x t u r e and C h e m i s t r y of S e l e c t e d P l a n t Communities 5.9. •4.3.5 S u c c e s s i o n of V e g e t a t i o n 62. 4.3.6 P r o x i m a t e A n a l y s i s o f S e l e c t e d P l a n t Communities 74,; 5.0.0 AQUATIC INVERTEBRATES 82. 5.1.0 M a t e r i a l s and Methods 82. 5.1.1 Sampling T e c h n i q u e s 82. 5.1.2 I d e n t i f i c a t i o n and S t a n d i n g Crop D e t e r m i n a t i o n 84. 5.2.0 R e s u l t s and O b s e r v a t i o n s 85. 5.2.1 S t a n d i n g Crop and D i v e r s i t y i n H a b i t a t Types 85. 5.3.0 D i s c u s s i o n 96. 5.3.1 D e n s i t y and Y i e l d o f I n v e r t e b r a t e s i n V a r i o u s H a b i t a t Types and T h e i r R e l a t i o n s h i p t o Brood D i s t r i b u t i o n 96; 6.0.0 WATERFOWL 109. 6.1.0 M a t e r i a l s and Methods ' 109. 6.1 . 1 Pa i r s 109. 6. 1 .2 N e s t s 1 10. 6. 1 .3 Broods M l . 6. 1 .4 P r e d a t i o n 1 12. 6.1.5 Movements o f - L o c a l Waterfowl 1 12. 6.1 .6 H u n t i n g E f f o r t , S u c c e s s and S p e c i e s C o m p o s i t i o n of t h e K i l l 1 14. R e s u l t s and O b s e r v a t i o n s . 1 17. 6.2. 1 S p e c i e s C o m p o s i t i o n and D i s t r i b u t i o n of B r e e d i n g P a i r s 117. 6.2.2 Genera 1 N e s t Data 120. 6.2.3 Brood Data 127. 6.2.4 Brood Movements .132. 6.2.5 P r e d a t i o n 136. 6.2.6 F a l l and W i n t e r Movements of L o c a l Wa+erfowl 139. 6.2.7 H u n t i n g E f f o r t 143. 6.2.8 H u n t i n g Success 146. 6.2.9 S p e c i e s C o m p o s i t i o n o f t h e K i l l 148. - v i i -Page. 6.3.0 Di scussion . 150. 6. 3. 1 Suitability of Habitat Types for Territory and Nesting ,150. 6. 3.2 Suitability of Habitat Types for Brood Rear i ng 189. 6. 3.3 Effect of Predation on Waterfowl Productivity 205. 6. 3,4 Productivity of Local Waterfowl 214,.-6.. 3.-5 Use of Marshes by Moulting Adult Waterfowl 221 . 6. 3.6 Migration Routes and Wintering Areas of Local Waterfowl 227. 6. 3.7 Waterfowl Harvest Data in Pitt and Alouette Polders 232. .6.4.0 Management Suggestions 246. 7.0.0 SUMMARY 262. LITERATURE CITED 266. APPENDICES - V i 1 i -LIST OF TABLES Page. Table I M-1: Nomenclature and Acreage of Habitats Selected for Field Investigation in Study Area - 1972 and 1973 10. Table 111-2: Average of Monthly Means of Maximum and Minimum Temperatures and Precipitation for 22-year period. Pitt and Alouette Polders, 1952-73 19, Tab Ie I II-3: UtiIi zation of Land in Pumped Areas of Pitt and Alouette Polders - 1972 and 1973 24. Table IV-I: Dry Matter Yields, Protein and Phosphorus of Selected Standing Crops - 1972 35. Table IV-2: Dry Matter Yields of New Growth, Old Growth and Duff from Selected Plant Communities Obtained on Four Occasions During the Growing Season - 1973 37. Table I V-3: Crude Protein Content of New Growth, Old Growth and Duff from Selected Plant Communities Obtained on Four Occasions during the Growing Season - I 973 39. Table IV-4: Crude Protein Present in New Growth and Combined Old Growth and Duff Fractions of Select Plant Communities During Growing Season - Pitt Valley, 1973 40. Table IV-5: Average Water Quality Data of Six Habitats in the Pitt Val ley - .1972 and 1973 45. Table IV-6: Soil Characteristics of Two Common Plant Communi-ties Subjected to Different Water Regimes - 1973 47. Table IV—7: Some Characteristics of Soils Supporting Four • . Different Plant Communities - 1973 48. Table V-I: Number of Families and Yield of Invertebrates in the Six Habitat Types as Revealed by Two Methods of Sampling - 1972 86. Table V I — I: Species Composition and Distribution of Adult Puddle Ducks in Selected Habitats - Pitt Valley, February 23 - 24, 1973.. 118. - i x -P a g e . T a b l e V I - 2 : . S e q u e n t i a l O b s e r v a t i o n s o f B r e e d i n g P a i r s i n • V a r i o u s H a b i t a t s - P i t t Va.l l e y , 1973 .119. T a b l e V I — 3 : Number o f B r e e d i n g P a i r s O b s e r v e d i n V a r i o u s H a b i t a t s D u r i n g P e a k o f N e s t I n i t i a t i o n f o r R e s p e c t i v e S p e c i e s - P i t t V a l l e y , 1973 119. T a b l e V I-4: N e s t s F o u n d i n P i t t a n d A l o u e t t e P o l d e r s ' -1972 a nd 1973 121. T a b l e V I - 5 : D i s t r i b u t i o n o f B r o o d P r o d u c t i o n i n S t u d y A r e a 128. T a b l e V I - 6 : B r o o d C o u n t s i n t h e V a r i o u s H a b i t a t T y p e s o f t h e S t u d y A r e a - J u n e , 1972 a n d . 1 9 7 3 129. T a b l e V I —7 : D u c k l i n g S u r v i v a I T h r o u g h S u c c e s s i v e A ge C l a s s e s , P i t t V a l l e y , . 1972 a n d 1973 . '. 131. T a b l e V I - 8 : I n s t a n c e s o f P o s s i b l e P r e d a t i o n i n S t u d y . A r e a - 1972 a n d 1973 137. T a b l e V I - 9 : S i g h t i n g o f P o t e n t i a l P r e d a t o r s i n S t u d y A r e a - 1972 a n d 1973 138. T a b l e V I — I 0: D i s t r i b u t i o n o f D i r e c t a n d I n d i r e c t Band R e c o v e r i e s A c c o r d i n g t o S p e c i e s a n d Age -P i t t V a l l e y , .1972 and 1973 142. T a b l e V I - I I : L o c a t i o n o f L o c a I I y - r a i s e d Wood D u c k Band R e -c o v e r i e s A c c o r d i n g t o Age C l a s s - 1972 a n d 1973 142. T a b l e V I - 1 2 : , M e m b e r s h i p a n d A c r e a g e C o n t r o l l e d by Gun C l u b s i n t h e P i t t V a l l e y - 1972 and 1973 145. T a b l e V I — I 3: H u n t i n g E f f o r t on " O p e n i n g Day" i n S e l e c t e d -A r e a s o f P i t t P o l d e r - 1972 and 1973 145. T a b l e V I - 1 4 : H u n t i n g S u c c e s s o f C l u b a nd N o n - c l u b Members on " O p e n i n g D a y " - P i t t V a l l e y , 1972 a n d 1973 147. T a b l e V I - 1 5 : H u n t i n g S u c c e s s o f C l u b a nd N o n - c l u b Members o v e r t h e E n t i r e W a t e r f o w l S e a s o n - P i t t V a l l e y , 1972 a n d 1973 147. T a b l e V I - 1 6 : S p e c i e s C o m p o s i t i o n o f W a t e r f o w l K i l l i n t h e P i t t V a l l e y - 1972 a n d 1973 149. Pag Table VI-17: Calculated Number of Breeding Pairs Successfully Hatching a Brood -. Pitt Valley, 1973 216 Table V1 — 18: Calculated Flying Young Raised in Selected Habitat Areas - Pitt Valley, 1973 216 Table VI-19: Estimated Flying Young Raised in Sturgeon S.I. Marsh & Wild land & the Public Shooting Marsh, Pitt Val ley, 1973 216 Table VI-20: Calculated Pair & Brood Productivity in Selected Habitat Areas - Pitt Valley, 1973 218 Table VI-21: Number of Broods Censused in Selected Habitat Areas - Pitt Valley, 1972 & 1973 218 Table V I-22: Origin of Mallards Banded as Flightless Young and Subsequently Recovered in Lower Fraser Valley, 1924-1972 Table VI-23: Utilization of Wood Duck Nest Boxes Placed on Metal Poles - Sturgeon Slough Marsh, . 1973 and 1974 244 254 - xi -LIST OF FIGURES F i'gure I I I - I : Figure I I I-2: F i gure IV-I: Figure IV—2: Figure I V—3: Figure I V—4: Figure IV-5: Figure IV-6: Figure IV-7: Figure IV-8: Fi gure V- I :. Figure V-2: Figure V-3: The Study Area Location of Habitats Selected for Field Investigation in Study Area - 1972 and 1973 Chronology of Water Level Fluctuations in Sturgeon Slough Marsh - 1972 and 1973 Chronology of Water Level. Fluctuation in Sturgeon Slough Wildlands at Furthest Point from Gravity Flow Outlet - 1972 and 1973 Sheet Water.on Farmlands of Ag. I resulting from Spring Freshet in Adjacent Rivers.- 1972 Change in Spatial Distribution of Run-off Pool in Portion of Pitt Polder Succession During 24 years has Resulted in a Reduction of Open Water Areas of Many Sloughs (A) Reduction of Open Water in an Established Bog and the Advance of this Bog into Adjacent Shrub Communities During a Twenty-four-Year Period Mat-formation in Peat Ponds North of. Burnt Mounta i n - I 973 Early Aquatic Succession Showing Extension of Emergent Sedges Zone at Expense of Open Water Areas Relative Numbers and Yields of Twelve Important Invertebrate Families in Three Selected Habitats Relative Proportions of Twelve Invertebrate Families Among Three Selected Habitats - 1973 Distribution of Yield of Twelve Invertebrate Families Among Three Selected Habitats - 1973 Page. 6. 43. 44. 52. 69. 71 72, 72. 90. 91 .92. Figure V-4: Distribution of Invertebrates -Yield of Potentially Important Ag. I, 1973 93. xl i -Page. Figure V-5: Figure V-6:. F i g u re V I - I : F i gure V I-2: Figure V1-3: Figure VI-4: Figure VI-5: F igure V I-6: Figure V1-7: Figure VI-8: Figure V I -9: Figure V I — I 0: Figure V I-I I: Figure V I - I 2: Figure VI-13: Figure V1-14: Distribution of Yield of Potentially Important Invertebrates - Ag. I I , 1973 Distribution of Yield of Potentia I Iy . Important Invertebrates - Sturgeon SI. Marsh,. 1973 Immature Female Mallard with Attached Numbered . Red Nasal Marker Immature Male Wood Duck with Attached Numbered Yellow Nasal Marker Mallard Hatching Curves for Pitt and Alouette Polders - 1972 and 1973 Blue-winged and Cinnamon Teal Hatching Curves for Pitt- and Alouette Polders -1972 Wood Duck Hatching Curves for Pitt and Alouette Polders - 1972 and 197.3 Mallard Nest Located in Dense Stand of Reed Canary Grass. Note the Almost Total Dependence on the Previous Year's Vegetative Growth for Concealment.. Brood Cover Created Along the.North Alouette Ri ver. - J une., I 973 . Status of Hunting Opportunity in the Pitt Valley. - .1972 and 1973 Roadside Ditch in Ag. I of the Type Utilized by TerritoriaI Pairs Remnant of Natural Slough s t i l l Used by Breeding Pairs. Note Recent Fi l l in the Foreground Ditch in Ag. I showing lack of Loafing Stations along either the bank or in the Ditch Proper Potential Ditchbank Nesting Cover Destroyed by Early Spring Burning 1973 Mallard Nest Denuded of Concealing Cover by Late Spring Burning- 1973 Destruction of Cinnamon and Blue-winged Teal Nesting Cover During Peak of Nesting Season. Yellow Flag Marks a Nest Previously Undergoing Incubation - 1973 94. . 95. I 15. 'U5. 122. 122. 126. 123. 134. 144. .152. 152. 154. 58. 158. 161 - X i i i -Page. Figure V I - I 5: F i gure V I - I 6: F i gure V I - i 7: Figure VI-I 8: Figure VI-I 9: Figure VI-20: F i gure V I-2 I: Figure VI-22: Figure V I-23: Figure VI-24: Figure VI-25: Figure V I-26: Figure VI-27: Figure VI-28: Cinnamon Teal Nest Destroyed by Roadside Mowing - 1973 . Banks of Wilson Slough showing complete re-moval of potential nesting cover by grazing Though shunned by grazing cattle, Juncus spp. provide little nesting opportunity due to frequent flooding Impenetrable growth of hardhack along ditch-banks in the Dense Wildlands Seasonally flooded "peat pond"' typicaI of the SweetgaIe-Sphagnum community - Dense Wildlands Mounds of substrate left in the middle of borrow-pits during construction provide some loafing sites for waterfowl Exposed Shoreline in the Sturgeon Slough Marsh Created by Low Water Conditions in early Spring. When Present, these Mud Flats were ExtensiveIy Used by Pre-Nuptial Waterfowl Calculated Hatching Period for Ground-nesting Waterfowl in Relation to Water Regime in Unpumped Habitats Small Pieces of Planking Used Extensively as a Haul-out Location by Loafing Ducks Walkway to Hunting Blind Showing Heavy Use by Loafing and Moulting Waterfowl Maintenance of Ditches Leaves Little Brood Cover in, and Adjacent to, These. Waterbodies Dense Beds of Smartweed in Section of Sturgeon Slough. Prior to Reclamation, Many Sloughs Were Vegetated in this Manner Flooded Cover Adjacent to Sturgeon Slough Used Extensively by Broods - June, 1972 Female Cinnamon Teal Being Fed on by Female Marsh Hawk -^ApriI, I 973 161 166. 166,. 169. 169. 175. 179. 180. 184. 184. 192. 196. 198. 210. - xiv -Page. Figure V 1-2.9.: Pre-Moulting Mallards and Wood Duck in Floating Funnel Trap - Sturgeon Slough Marsh, 1973 223. Figure VI-30: Suggested Sites for Erection of Wood Duck Nesting Boxes . . 249. pUt- f l /o« - t t t i P«(io i/«jdr<cUv p0cUf 1. 1.0.0 INTRODUCTION The extensive area of freshwater marsh, bog, stream, low knoll and wooded piedmont remaining at the lower or southern end of Pitt Lake may be regarded as singular not only.for its varied lowland, habitats but also for its siting ten miles from a metropolis of a mi I I ion people. With the exception of the Pitt Lake area, there remains, in southern British -Columbia; little lowland landscape which has not. been greatly modified by man, his transportation system, his housing, his agriculture and his industry. On Iy recent Iy have attempts to establish arable agriculture in the area met with success because drainage has proved to be difficult and -for decades much of land has been the domain 'of•private gun clubs. The interest of the community at large in the Pitt Lands is now growing rapidly and pub ILc waterfowl hunting, bird watching, canoeing, hiking and other "exten-sive recreational activities have been signalled by public land acquisition. With the pub Iic interest now well established, and an attendant increase in public use, control and management of the Pitt lowland is imperative if its natural features are to be conserved. • In the expectation that most of the area may continue to exist as near-natural, enhanced-natura I and as "'1 farmland and forest land, this, study was undertaken. It is deliberately broad and is an attempt to identify major factors which relate to conservation of the waterfowl of the Pitt. 2 I.1.0 CONVERSION TABLES FOR BRITISH AND METRIC WEIGHTS AND MEASURES The f igures In the central of the three columns In each table represent e i the r one or the other of the two side columns, as requ i red , e . g . I kg = 2.205 lb', I lb = 0.454 kg, 100 ha = 247.105 ac , 100 ac = 40.469 ha. Kl lograms WE IGHT kg or lb Pounds (av)* ( lb) Hectares AREA ha or ac Acres* kg/ha WE IGHT/AREA kg/ha or Ib/ac Ib/ac *( 0.454 1 2.205 0.405 1 2.471 1 . m 1 0.892 0.907 2 4.409 ' 0.809 2 4.942 2.242 2 ' ' 1.784 1.361 3 6.614 1.214 3 7.413 3.363 . 3 2.677 1.814 4 8.819 1.619 4 9.884 4.484 4 3.569 2.268 5 11.023 2.023 5 12.355 5.605 5 4.461 2.722 6 13.228 2.428 6 14.826 6.726 6 5.353 3. 175 7 . 15.432 2.833 • 7 17.297 7.848. 7 6.245 3.629 8 17,637 3.237 8 19.769 8.969 8 7. 138 4.082 9 19.842 3.642 9 22.240 . 10.090 9 8.030 4.5356 10 22.046 4.047 10 24.711 1 1 .21 1 10 8.922 9.072 20 44.092 8.094 20 49.421 22.421 20 17.844 13.608 30 66.139 . 12.140 30 . 74.132 33.632 30 26.766 18.144 40 88.185 16.187 40 98.842 - 44.843 40 33.688 22.680 50 110.231 20.234 50 123.553 56.054 50 .44.609 27.216 60 132.277 24.281 60 ' 148.263 67.265 60 53.531 31.752 70 154.324 28.328 70 172.794 78.486 70 62.453 36.287 80 176.370 32.375 80 197.684 89.696 80 71 .374. 40.823 90 198.416 36.422 90 222.395 100.907 90 80.296 45.369 100 220.462 40.469 100 .247.105 112.108 100 89.218 lb(ay) = 16 ounces (oz) * 1 acre = 4840 sq yards hundredweight (cwt) = 112 lb . C e n t i -metres or 2.540 hm -10.160 12.700 15.240 17.780 20.320 22.860 25.400 50.800 76.200 101.600 127.000 152.400 177.800 203.200 228.600 254.00 LENGTH cm. n. m or VOLUME I or 9 10 20 30 40 50 60 70 80 90 100 Inches . Metres yd. Yards* 0.394 0.914 I 1 .094 0.787 1 .829 2 2.187 1 .181 2.743 3 3.281 1.575. 3.658 4 4.374 1.969 4.572 5 5.468 2.362 5.486 6 6.562 2.756 6.401 7 7.655 3.150 7.315 8 8.749 3.543 8.230 9 9.843 3.937 9.144 • 10 10.936 7.874 18.288 20 21.872 11.811 . 27.432 •30 32.808 15.748 36.576 40 43.745 19.685 45.720 50 54.681 23.622 54.864 60 65.617 27.559 64.008 70 76.553 31.496 73.152 80 87.489 35.433 82.296 90 98.425 39.370 91.440 100 109.361 f l yd = 3 f t = 36 Inches L i t r e s ga 1 Ga1 Ions* 4.546 1 0.220 9.092 2 . 0.440 16.638 3 0.660 18.184 4 0.880 22.730 5 1 . 100 27.276 6 1.320 31.822 7 1.540 36.368 8 1.760 40.914 . 9 1 .980 45.460 10 2.200 90.919 20 4.400 136.379 30 6.599 181.839 40 8.799 227.298 50 10.999 272.758 60 13.199 318.217 70 15.398 363.677 80 17.598 409.137 90 19.798 454.596 100 21.998 * 1 l gal = 8 p ints 3 . 2.0.0 ACKNOWLEDGEMENTS Partial financial assistance from the Canadian Wildlife Service and the B.C. Fish and Wildlife Branch during the preparation of this thesis assisted greatly to its completion. Similarly, certain professional staff from both these organizations gave freely of their time and advice through-out. In this regard,. I would like to extend thanks to Mr. Bob Harris, Mr. Ernie Taylor, Mr. Bill Morris, Mr. Don Trethewey and Mr. Malcolm Noble of the Vancouver office of the Canadian Wildlife Service and to Mr. Ray Ha I Iaday of the B.C. Fish' and Wild Iife.Branch in Victoria, B.C. A special thank you is extended to Bob Harris, not only for initia-ting this study, but also for and encouragement during the last nine years as I pursued a career in the wildlife field. My supervisor, Dr. V.C. Brink, of fered. gu i dance throughout .the study and was particularly patient of my efforts to "understand" and interpret the significance of vegetation in the study area. Dr. Bob Hudson, formerly of the Department of Animal Science, U.B.C., also gave generously of his time in reviewing various data. However, finances and advice notwithstanding, this thesis, in its present form, could not have been concluded without the dedication and . enthusiasm of Mr. BiI I Damon, Mr. Chris Easthope and Mr. Al Vaudray during the collection of field data. Often working from dawn to dusk, under trying conditions for little or no remuneration,- I extend to these gentle-men my deepest appreciation. Other organizations and individuals extended help and advice, including Mr. Richard Tret.hewey, Mr. Bill Otway, Mr. Harold Haywood, Mr. Bill Laseur, Mr. Hank Tenbrink, the Sturgeon Slough Game Club, Mr. Gary Kaiser and Mr.Bruce Burton. To these, I offer a sincere thank you. The unenviable chore of translating my handwritten notes during typing of the first draft was performed by Miss Diane Sharpe. Final copies were typed accurately by.Ms. Marianne Strueby. Finally., for his constant companionship and devotion in the field,' and his invaluable assistance in capturing flightless waterfowl, I would like to acknowledge my retriever, "Happy". 3.0.0 STUDY AREA DESCRIPTION 3.1.0 . Location and Physiography The study area (see Fig. Ill-I), consisting of almost 7,780 acres, is located north of the Fraser River, approximately 30 miles east of the City of Vancouver, B.C. Its natural boundaries are Pitt Lake to the north, P'itt River to the west, a spur of the Golden Ears and Blanshard Mountains.on which U.B.C. Research Forest is located to the east and the South Alouette River to the south. The topography of the area is essentially an alluvial plain which surrounds three granitic outcrops, the highest of which rises to the height of 375 feet above sea level. The plain consists of deltaic deposits from the Fraser and Alouette Rivers and is comparatively level; the undulations between bottom and crest rarely exceed 15 feet. The minor undulations result in the formation of many poor ly'.dra i ned depressions. In addition, the Pitt and Alouette Rivers have meandered across the floodplain in the past, creating new channels and abandoning old ones. These latter contributed further to the sloughs and depressions found throughout the area (Holland et aj_., 1956). Twice 'in'the last 60 years attempts have been made to-reclaim the flood-prone lowlands. As a result the entire area is encompassed by a series of dykes that isolate it from the tidaI Iy-infIuenced Pitt Lake and Pitt and Alouette rivers. These dykes are vegetated mainly by dense stands of reed-canary grass and occasional clumps of blackberry. On the inside perimeter, removal of. fiI I during dyke construction has created a water-fil ditch or "borrow-pit", averaging 30 feet wide and 3 - 5 feet deep. '. At the time of dyking the entire acreage of lowlands was cross-ditched 6. 7. These ditches, one-quarter mile apart and running east-west and north-south, vary in width and depth but in.all cases are considerably smaller than the borrow-pits. In the farmed portion of the study area many of the ditches have been incorporated into the current drainage system and are regularly maintained by drag-lining. When not subjected to grazing and/or cutting, . these ditchbanks are vegetated primarily by blackberry, willow and various grass species. In the approximately 3,000 acres of lighly managed lands in the northern end of" the study area many of the cross-ditches have become part-ially filled by sedimentation, slumping and vegetation. The vegetation of this unmanaged area as a whole is a mosaic of dense hardhack stands and open meadows of bluejoint and various sedges; ericaceous species are domi-nant in the scattered peat deposits and both emergent and submergent aqua-tics occur in the, marshes. Alder, cottonwood, crab apple, hawthorn and willow grow profusely along some dykes and channel banks. In addition, a number of large coftonwoods are sporadically located along the ditch banks. Though modified to varying extents by infilling and vegetation, many of the former sloughs and channels present prior to the original dyking are s t i l l in evidence. . In much of that portion of the study area managed for agricultural purposes, various activities associated with farming have resulted in the elimination of many depressions and sloughs. Most that remain have been modified into drainage ditches. In these areas the predominant vegetation is associated with agricultural practices and consists largely of pasture, hay, and fodder crops such as corn. Natural vegetation, where it has not been cleared for agricultural purposes, consists of dense stands of hard-hack. Interspersed among the hardhack are ribbons.of bulrush and sedges and these often mark the location of former sloughs and channels. Some large cottonwoods are found, particularly along ditchbanks.. Throughout the farmlands, road verges are primarily vegetated by a luxurious growth of reed-canary grass. By contrast, road sides in the lightly managed area tend to be a heterogenous mix of grasses, shrubs and trees. The vegetation of the three rocky outcrops is quite different to that found on the adjacent floodplain. The smallest of the outcrops, known / locally as "the Knoll", is essentially unmodified by burning or logging and is established to-climax douglas f i r ; the understory consists predom-inately of salal. The vegetation of the other two knolls known locally as "Burnt" and "Green" mountains is in various stages of secondary succession following man-made disturbances. Green Mtn. particularly is densely wooded with a deciduous tree cover consisting largely of alder, birch and broadleaf maple. Scattered throughout are remanant douglas f i r and the occasional western red cedar. Burnt Mtn., logged and burned in the 1950's, ' is less heavily wooded, and on the upper parts is estabIished an open "rocky bluff flora"* Around the base of the outcrop is a dense stand of . IodgepoIe pine, intermixed with western red cedar and douglas f i r . Native crab apple virtually encircles the entire outcrop where it grades into.the alluvium. Due to the size of the study area it was deemed necessary to restrict detailed field investigations to a series of smaller, more manageable units (see Fig. 111-2). These were selected on the basis of gross vegeta-fionai' characteristics and land use and, for convenience, each is subsequent-ly referred to as a habitat type. The name of each of these units.and the approximate acreage involved is I i sted i n Table I M-l. *,Northernmost representations of a coastal flora characterized by.shallow soils, summer drought and plants such as CaIifornia Oatgrass (Danthon ra  californica), Little Hairgrasses (Aira spp.) and many shrubs and forbs. 10. Table l l l . - l : Nomenclature and Acreage for Field Investigation of Habitats Selected in Study Area, 1972 and 1973 Approximate Habitat Type Acreage Agriculture 1 (Ag.1) 809.. Agriculture 11 (Ag. II) 560 • Open Wi1d1ands 565 Dense Wildlands 454 Sturgeon Slough Marsh and Wildlands 2,554 Publ ic Shooting Marsh (P.S.M..) 582 11. 3.2.0 History The original inhabitants of the Pitt Meadows region, which includes the study area, were the Katzie Indians, one of a number of. Coast Salish groups in the Lower Fraser Valley. The Katzie were never numerous and only 127 individuals were enumerated in the Indian Dept. census of 1879. The yearly schedule of the Katzie (Jenness, 1955; Suttles, 1955) suggests that the marshes and meadows of the study area were used extensively, primarily, as a food source. Villages were estabIished in the area and were occupied for approximately 6 months of each year; the other 6 months were spent at sites along the Fraser, primarily to exploit the fishery. The most important food plants harvested in the area were bog cran-berry (V_. oxycoccus) and wapato (S_. I at i f o I ia) (Suttles, 1955). The former was readily available in the four or five major areas of sphagnum bog located in Katzie territory (Jones, 1972). The tubers-of wapato or duck potato were harvested from the many marshes and ponds of the area during.October and November. Deer (Odocoileus hemionus), goat (Oreamnos  americanus), elk (Cervus canadensis) and bear (Ursus spp.) were obtained from either the lowlands or the adjacent mountains, depending on local habits of the respective species. The waterfowl resource was utilized extensively during periods of peak abundance, which, in the Katzie area, occurred from October to March (Jones, 1972). Many of the streams supported fish runs of local importance; Chum salmon (Oncorhynchus keta) runs began in the end of August, on Widgeon Creek and in the beginning of September on the North and South Alouette, and Sturgeon Slough. In June, squawfish (PtychocheiI us oregonensis) and peamouth chub (Mylo.cheiI us caurinus) con-gregating in the shallower waters of streams, provided an additional source of food. 12. Exploration of the Pitt Meadows area by white men occurred between 1837 and 1858. By 1882, permanent settlement of the area was taking place but was largely restricted to the lands just above flood level. Following the construction of.the C.P.R. along the north bank of the Fraser River, many more settlers moved in to log the virgin timber and farm the grassy flat-land. Farming consisted of grazing cattle and making of wild hay; these activities, however, were largely governed by the annual spring flooding of the Fraser, Pitt and Alouette rivers. Some protection of individual properties was attempted during this period by the construe-, tion of hand-built dykes. Following the disastrous flood of 1894 a concerted effort was made to secure, by extensive dyking, the lowlands south of the South Alouette River. It was not until 1909 that reclamation of the lands north of the North Alouette River were considered. In March of that year Mr. W.A. Rann ie app I led.- for the right to purchase these lands, then known as .the Pitt River Meadows. On June 2, 1909, a Federal Order-in-CounciI authorized the sale to him of approximately 6,800 acres at $1.50 per acre, subject to three-conditions; I) that plans be submitted in 6 months; 2) work to commence within 18 months; and 3) that work to be completed within 4 years of the passing of the Order-in-Counci I.. The initial dyking began in 1911 and involved construction of dykes along the southern margin of Pitt Lake and along the east bank of the Pitt River. A system of ditches was dug and a pumping station capable of handling 20,000 gallons per minute was installed on Sturgeon Slough. This was located approximately on.e mile upstream from the confluence of the slough.and the Pitt River. This was complemented by a sraaI I.gravity-flow system that drained into the Pitt River, via the borrow ditch, approximately 13. a mile below the southern end of Pitt Lake. In keeping with the terms of the sale, reclamation work was completed by June 1913, and, in December, 1915, a patent was i ssued to Rann i e for 6,814.I . acres. In ApriI,. I 918, this was subsequently amended to include a total of 6,876.2 acres. Permanent settlement of the reclaimed area was not possible because the dykes proved to be too low and the pumping faciIities inadequate to handle the volume of, water involved (Vanderh i I I , ,1962). Gravity overflow was restricted by the single small culvert used as an outlet; also, the tidaI nature of Pitt,River and Lake only permitted an outflow of water when the water-level outside the dyke was low enough to permit the water pressure-operated gate on the open. The land was subsequently sold for taxes after World War I and the new owners encouraged a small number of Mennonites to attempt settlement in the area. Because the drainage system and dykes were not improved, settlement was soon abandoned. Again, the land was sold, this time to a group of wealthy sportsmen who founded the Sturgeon Slough Game Club. Primarily concerned with using the land for duck hunting, this group did li t t l e to improve the drainage system. Nevertheless, individuals willing to attempt farming under these conditions were allowed to do so on a- rental basis. During the Depression years as many as six individual farmers homesteaded in the area, most paying approximately $7 per month for the use of house and land. Most of these limited their efforts to grazing cattle and cutting wild hay, the latter operation in late June. Pumping was usually attempted each spring to hasten removal of wafers and once gone the area did not flood extensively again until the. following winter in most years. There were however exceptions, when high level spring flooding occurred, particular instances being in 1921, 1935 and. 1948 (McDer-14.. mott, 1967). In 1948, over 300 feet of dyke at the southern tip of the lake were washed but and flooding was particularly extensive. This point in the dyke was subsequently repaired by the provincial government but be a weak spot for several years due to wave action of the I a ke. Ln 1952 the Bennett government came to power and shortly after, imposed a school tax on the land which raised the taxes from $1,800 to $4,600 per year. Faced with this increased charge and the increasing expense of a deteriorating dyking system, the club.members decided to sell the. lands (Ladner, 1973). Through the Consul General for the Nether-lands in Seattle, the club learned of the interest by a Dutch group in the lands and a sale was eventually consummated. With the formation of a company, Pitt Polder Ltd., and the input of Dutch capital and reclamation expertise, engineering work on upgrading the dykes and drainage ditches began in 1951. The existing river dykes were built up from 13 feet to 16 feet above sea level and the crest widened from 6 to. 12 feet (Laseur, 1974). A new series of inner, dykes resulted in major changes in the drainage pattern of the area. A first series of dykes involved the building of a diversion to intercept the run-off waters from the mountain slopes to the east. A second series involved integra-tion of the interior dykes with a ditching system in such a manner that two separate areas of approximately 3,000 and 3,100 acres respectively were created. This partitioning of the area was followed by the construction of a network of roads and drainage ditches. ' In addition, two electrically operated pumps with a combined capacity of 90,000 gaI Ions per minute were installed on Sturgeon Slough to service the 3,000 acres in the southern portion of the.Polder (Klein, 1965). 15. The remaining'3,1 00 acres was left to the vagaries of the tidally-, influenced gravity flow system. The efficiency of the latter in deliv-ering water to the outlet was improved somewhat by the cutting of a drainage ditch leading from the Sturgeon Slough marsh to two new 48" diameter culverts. . This resulted in a more rapid run-off during periods of low water in the Pitt River. However, during the freshet period and •high-low tides little water was removed from this area. By 1952, control ". of the water-table in the 3,000 acres was well underway. Buoyed by their apparent success the Pitt Polder Co. looked to adjacent areas- for further reclamation opportunities. To the south of their current project lay. 1,100 acres of provincial Iy-owned marsh-and shrub-swamp. Bordered by the North and South Alouette rivers, this area was originally dyked in 1891 but seasonal flooding had prevented much agricultural development. After lengthy negotiations the government agreed to deed the land to Pitt Polder Co. for a cash payment of $9,670.and invest-ment of $116,000 in certain improvements. These included the following; I) rebuilding and upgrading 5 miles.of dykes, 2) construction of north-south and east-west cross-ditches every n mile -- a total of 14 miles of ditch, 3) installation of an adequate pumping system and 4) cutting 700 acres of hardhack. A time limit of three years was placed on the company to perform these improvements. However, it was June, 1964, some twelve years and $1.47,000 later, before all improvements were f i na I I y comp I eted .. Nevertheless, the original agreement stood and the area, now known as Alouette Polder, was deeded at,that time to C.B.A. Engineering Co. Ltd., a subsidiary of Pitt Polder Co., Ltd. UnI ike the lands to the north the Alouette Polder was developed as a beef and hay operation and, by 1966, approximately 500 acres were being 16. utilized for that purpose., In September, 1973, G.B.A Engineering disposed of their interests in the Alouette Polder and ti t l e to the lands is now held by Pitt Polder Co., Ltd. With the improved pumps in operation it became possible to maintain the water table in the now-farmable 3,000 acres of Pitt Polder two to three feet below the ground surface. The pumps now handle the run-off from a. 24-hour rainfall of up to I?".. Control of the water table was followed'by clearing the land of brush and marsh cover, digging field ditches for . surface drainage and laying t i l e for underdrainage. The ground was broken and a cover crop of oats, clover and grass planted. By the late fifties , 860 acres had been thus prepared and nine individual tenant farmers. Initially it was planned to include crops in the agricultural base of Pitt Polder and, to this end, experimental plots of oats, peas and potatoes were planted. However, the results were less than encouraging, and subsequent effort was devoted almost entirely to the development of dairy farming. Up to the late fifties the system of new and rebuilt dykes in Pitt Polder seemed secure, with one exception. This was the 300 feet of dyke at the south end of Pitt Lake that had- washed out in 1948. Though rebuilt by the Dutch settlers in 1951 and subsequently re-surfaced with a concrete "apron" this stretch of dyke remained a problem area until 1957. At that time built, a dyke approximately one mile north of the trouble spot that effectively cut-off the lower 582 acres of the lake from the main body of water. This dyke was subsequently up-graded by the provincial government to Dept. of Highways specifications. The 582 acres of enclosed marsh.was then deeded to the Fish and Wildlife Branch and became the Public Shooting Marsh. Prior to 1966 in excess of 1,100 acres north of Sturgeon Slough was held under lease, with an option to purchase one-half the acreage, by the Netherlands Overseas Corporation. However, in that year this tract of land came under the control of Pitt Polder Co., Ltd. Part of this land has since been developed for dairying and is. occupied by a tenant farmer. A further, land transaction of some significance occurred during the current study. In August, 1972, all but approximately 400 acres of the unpumped lands in Pitt Polder were sold to the Government of B.C. for green-belt purposes.. This tract is currently held for the Provin-cial Crown by the B.C. Land Commission and decisions for its management have yet to be made. Pitt Meadows had originally been included in the Municipality of Maple Ridge when that area was incorporated in 1874. Shortly thereafter the local landowners of Pitt Meadows petitioned Victoria for the succes-sion of the Pitt Meadows area and this was granted in 1896. Finally, on April-23, 1914,.the Municipality of Pitt Meadows was incorporated. At present all of Alouette Polder and approximately 135 acres of Pitt Polder are on the municipal tax rolls and receive the services and utilities administered by Pitt Meadows Municipality. The rest of the study area, namely, most of Pitt Polder is administered by the Province. School and land taxes are paid directly to Victoria by the landowners; services such as water, garbage collection and police protection are arranged at the local level. In terms of regional government, the study area is located within the Dewdney-AIouette Regional District. 18. 3.3.0 Climate The climate of the study area and adjacent Lower Fraser Valley is described as a modified maritime climate (Kendrew and Kerr, 1955). During the winter months storms of varying diameter bring heavy precipitation and coo I-to-cold temperatures to the study area. During the summer, storm tracks are located to the north resulting in generally clear skies and moderate to warm summer temperatures.for the south coast. The mean annual temperature for the study area is 49.3° F- compared to the annual mean of approximately 50.0° F experienced in the rest of the Valley. January is coldest with an annual mean of 35.5° F (see Table I I 1-2). An annual mean of .63.1° F for July makes this the warmest month in the study area. According to Stager and Wall is (1968) the study area generally strad-dles the 200-day frost-free isocline. However, the low elevation of the area (ca. 5 feet above sea-1 eve I) and the effect of cold air ponding behind dykes, creates local frost pockets. In some localities, the frost-free period is thus shortened, especially in and adjacent to the wetter, unpumped lands. A similar situation exists in areas near Steveston and Ladner which may have only 183 frost-free days although the 200 day isocline generally encompasses that portion of the Fraser delta. The timing of the last frosts of spring is of agricultural importance. Though . Iast-frost dates are.not available for the study area per se, the-Haney area, 8 miles to the south, generally records the'last frost dates in the second and third weeks of April. Due to the ponding of cold air behind the dykes frosts very pro-bably occur later' in the study area. The basic cause of precipitation in the Lower Fraser VaI ley . region is frontal lifting (Stager and Wall is, 1968). In the study area the presence 19. Table I I 1-2: Average of Monthly Means of Maximum and Minimum Temperatures, and Precipitation for 22-year Period Pitt and Alouette. Polders, 1952 - 1973 Month Maximum January 40.5 February 45.7 March 50.2 April 55.9 May 64.4 June 68.3 July 74.2 August 73.3 September 67.5 October 57.9 November 47.9 December 43.2 Mean Annua I -Total Annual Temperature -. F M i n imum Mean Month 1y .30.5 35.5 33. 1 39.4 34.0 42. 1 38.3 47. 1 44.6 54.5 50.3 59.3 51.9 63. 1 52.1 62.7 47.6 57.5 41.9 49.9 36.2 42. 1 32.5 37.8 49.3 Prec i p itation Ra i nfaI I Snow TotaI 11.69 10.85* 12.78 9.11 1.86* 9.30 7.91 1.85* 8.10 6.17 - '" 6. 17 3.63 - 3.63 3.87 - 3.87 2.50 - 2.50 2.68 - 2.68 5.60 . - . 5.60 10.21 - 10.2.1 : 11.78 I.10* 11.89 13.79 5.02* 14.28 88.94 20.68* 91.01 * calculated as \0% rain. 20. of relatively high mountains oneither side may result in a "canyon effect" i.e. the lowlands reflect the precipitation of the mountain mass about them and not that characteristic of their elevation (Brink, 1946). This probably accounts for the relatively high annual total precipitation of 91.01" in the study area (see Table I I 1-2) as opposed to a 7-year average of 73.75" (Canada Dept. Transport, 1967) in Pitt Meadows just 5 miles to the south. The significance of precipitation of this magnitude becomes somewhat more meaningful when the seasonal pattern is considered. This reveaIs that.on Iy 9.05", or 10 percent of the total, occurs during the summer months: of June, July and August; almost 73 percent of falls from October to March. However, despite this strong winter peaking of precipitation, back-pumping to provide irrigation water in the agricultural areas has only been necessary once, viz. in July, 1958, when the average monthly maximum temper-ature reached 81.0° F and only 0.01" of rainfall was recorded.' " 21 . 3.4.0 Soils Though differing in origin, texture and nature, the soil-forming materia I s'. of. the study area share a common trait in that they were trans-ported by either.glaciaI or alluvial action to their present location. The. soils on the rocky outcrops (i.e.. Green and Burnt Mtns. and the Knoll) were developed from layers of sandy to silty t i l l and sub-stratified drift which were deposited on the bedrock by glacial action. . The lowland soils, however, reflect long-term deposition of alluvium from the Fraser River.. According to Roddick (1965) the Pitt Valley, if.not covered with ice, may well, have been a fiord at the close of the Pleistocene period. Conse-quently, as the land rose and sea retreated, Fraser River si Its were depos-ited and exposed in the Pitt Meadows area. From that time until dykes encircled the area in 1914 these alluvial deposits were augmented annually during the combined spring freshets of the Fraser, Pitt and Alouette Rivers. Thus, the bulk of the soils of the lowlands consist of silty clay, clay-silt •and s i l t up to 12 feet thick resting on 50 feet or more of marine and non-marine sand (Holland e_t a_l_., 1956). Some reworking of sediments has occurred in the vicinity of the North Alouette River and here the deposits are mainly sandy s i l t and s i l t up to 5 feet thick resting on marine and non-marine sand. Sedimentation is s t i l l occurring in undyked portions of the southern end of Pitt Lake, where as a resultant of tides on Pitt Lake and Pitt River, there is frequent reversible flow of water. At high tide, Fraser River sediments are carried up Pitt River and deposited in,the southern end of the lake CRoddick, 1965). Three great soil groups are represented, in the study area, namely, rego 22. gleysols, ferric humisols and lithic orthic humoferric podzols (Luttmer-. ding and Sprout, 1972). Reflecting divergent origins, these soils differ in both texture and constituency. In the marshes of the unpumped area the gleysols tend to consist of mediurn. .over moderately-coarse textured Fraser alluvium and have very poor drainage. The surrounding meadows and shrub swamp differ slightly in that the soil parent material is largely, medium textured alluvium. Drainage of these swamp soils is slightly improved.over that of the marsh gleysols, but is s t i l l classified, as poor. Deposits of terric humisols in the unpumped areas are found mainly in the vicinity of Burnt Mtn., the Knoll and Giley Slough. The soil of these deposits consists of moderately shallow, we I I-decomposed, organic accumu-lation associated with Fraser and Pitt river alluvium and is today estab-lished ericaceous plants (Appendix I). As with the marsh gley-sols these humisols have very, poor drainage; This contrasts sharply with the very rapid drainage occurring in the soils of Burnt Mtn. and the Knoll. This difference reflects the parent material of the rocky outcrops, a coarse and moderately coarse textured glacial t i l l and coI Iuviurn over impermeable gran ites. In the pumped areas the soils of the peat and rocky outcrop sub-areas are much the same as those of the unpumped area. The gleysols covering the lowlands are medium textured alluvium and are underlain here and there by moderately coarse textured a I Iuviurn which characterize the.unpumped soils at depth. 23. 3.5'.0 Socio-Economic Factors The major economic base of the study area- is agriculture. At present there are nine dairy farms, an ornamental plant nursery, and a blueberry and Christmas tree farm in Pitt Polder and a beef-hay farm in Alouette Polder. These enterprises are located in the pumped section of which approximately 1,200 acres has been tiled to further a id .• dra i nage. Disposi-tion of the enterprises is shown in Table I I 1-3. . . . . The diary and.beef-hay farms are operated by tenant farmers, who lease the land from Pitt Polder Company. The company is responsible for provision and maintenance of the farmhouse, barn and certain auxil iary bui Idings; the lessee provides the stock and farm equipment, In 1966, a 5-year lease was signed with each tenant for a rent of $35 per acre per annum. In 1971, new leases were negotiated with rents ranging from $45 to $55 per acre. Present indications are that future.I eases will be $70 to $75 per acre and will include a clause for yearly adjustment, the latter reflecting the current inflationary trend. (Laseur, 1974). The average size of the dairy farm is. 125 acres and each of these supports a Holstein milking herd averaging 63 animals. Conversion from stanch ion mi ng to the more modern milking parlour in the near future: will increase the average herd size to 80 - 100 animals within 5 years (Laseur, 1974). The blueberry and Christmas tree operation is operated by the parent Pitt Polder Co. and is not leased to private individuals; the 30 acre, nursery is owned and managed by the Netherlands Overseas Corporation. At present, 9 of the 10 farms are leased to farmers of Dutch ancestry. However, the company .claims that this was not planned and that farmers of non-Dutch extraction were given equal opportunity to apply when the leases 24. Table 1 1 1 - 3 : . Utilization of Land in Pumped Areas of Pitt and Alouette Polders - 1972 and 1973 LAND USE 1972 1973 •Appro r \ U r \ t o Pasture/Hay 1455. 1464 Rough Pasture 3 6 5 3 6 5 Wi 1 d1ands 1 5 3 4 1534 Cattails.' 3 . 3 Wood.lot 3 7 37 Cultivated Lands: Corn 143 117 Millet II 16 -Green Forage 27 37 Blueberries 107 107 Christmas Trees 3 . 3 . Grass 1 1 1 3 . Nursery 2 5 2 5 TOTAL 3 7 2 1 * . 3 7 2 1 * approximate acreages, calculated with planimeter. 25. were first offered. Indeed, company policy requires at least two years residence in.'Canada. prior to application for land (Vanderhill, 1962). There are several non-Dutch famiIies either owning or leasing land in Pitt Polder but with the exception of the Haywood property these are residential properties. The Haywood property, of approximately.80 acres, is used to . graze a few horses and cattle but is not farmed intensively. 26. 4.0.0 VEGETATION, SOILS AND WATER 4.1.0 Materials and Methods 4.1.1 Vegetation Cover Map A suitable base map had to be prepared prior to the development of a map of vegetation. The base map was traced, with some modifications, from an existing map (scale I" = 1,000') in possession of the ,CD.A. station, in Vancouver. Principal features were outlined and a number of prints made for field use. A series-of•aeriaI photos (Flight No. B.C. 7449), scale I" = 540', were then obtained and individually covered with Mylar paper. Each 9" x 9" print was examined and, within the bounds of resolution, a I I discrete blocks of vegetation were outlined. The area was then transversed, on foot -in most instances, and the outlined units of vegetation identified to the community level. Initially, it was hoped that once a given community was "keyed" in this manner its presence throughout the study area could be detected solely be examining subsequent air photos. However, variations in appearance of like communities due to tonal differences within a series of~air photos cast doubts upon the accuracy of such a procedure. Subsequently, an effort was made to visit all but the most obvious communities in the field, thus ensuring an accurate community designation. Upon completion of the identi-fication and delineation phase, the individual communities were then trans-cribed to the base map. Each community was assigned a Letraform symbol and the appropriate spaces on the map coded accordingly. Following completion of the master cover map a number of prints were reproduced to serve as work-i ng cop i es. 27. 4.1.2 Sampling of Vegetation (a) Terrestrial and Emergent Vegetation Using the cover map. (see Section 4.1.1) "pure" stands of the major plant communities were selected for sampling. Where possible duplicate stands were, selected, one being located in. an area where the water table was artificiaIly controlled by pumping and the other where little control was exercised. In total, three terrestrial and three emergent communities . were sampled in duplicate. Upon selection of a stand, plots to be clipped were "randomly" selected by.throwing the square metre metal frame back-wards's head. Using garden shears, or secateurs if necessary, the vegetation within the frame was clipped, at ground level and gathered for pIacement in tagged burlap sacks. In 1972 both the current year's growth and the old growth present were placed in the same sack. In 1973 these two components were segregated and placed in separate sacks. In addition, a third component, the duff, was.col Iected. For the purposes of this study duff is considered to be tha profile fraction of previous year's growth that has become.matted and/or partly decomposed. Another difference between years involved the schedule of collection and the number of plots sampled. In 1972, only one collection was made in the late summer when aerial dry matter was maximal, at which time 4 plots per community were clipped. In 1973 sampling was done on a sequential basis with .2 plots per community being collected at a similar time in each of the months of May, June, July and August. Upon completion of the field work the harvested material was taken to the Plant Science Field Laboratory at U.B.C. and placed in a tunnel dryer for approximately 72 hours. When dry the material was removed and weighed 28. to the nearest 0.1 gram. Each sample was then ground using a hammer mill and a sub-sample was reground in a Wiley mill. The sub-sample was then placed in storage until used for chemical analysis, (b) Submergent Vegetation In this study vegetation-norma'l Iy growing at or below the surface of a water body were considered submerged species. The establishment of the standing crop of submerged aquatics involves a number of problems not encountered when sampling terrestriaI.or emergent vegetation. Among, these are water depth and clarity, loss of material via current, and layering of distal ends of aquatic vegetation due to current, which, in turn, makes a basal area clip difficult to obtain. These and other prob-lems have led to considerable variety in modes of sampling submerged aqua-tics (Siegler, 1941; Birk, 1959; Keith, 1961; Jessen and Lound, 1962). 2 In this study am exclosure frame, 26 inches high, was constructed of galvanized sheet metal. A pointed metal stake approximately 6 inches long was riveted to each corner.of one end and handles fastened to two of the sides. Two methods were used in locating the plots. In the pumped area, where sampling was confined to drainage ditches, an "X" was randomly placed on a section of ditch on a 1,000 feet = I inch air photo. This spot was then located in the field and the sample collected.. This involved dropping 2 the m frame into the ditch, and then, using shears, clipping all enclosed vegetation at the soil-water interface. The vegetation was gathered as it floated to the. surface and placed in a cotton sack. Due to the heterogenous mixture of species in most stands it was decided to measure the standing crop of.submerged aquatics per se. 29: Due to "layering" of the vegetation the sampler would enclose, at its perimeter, the distal ends of adjacent plants rooted outside the plot and the proximal ends of vegetation rooted within the plot. Separation of roofings was impossible; therefore an ordinary lawn edger was used to sever vegetation by cutting around the inner edge of the frame. In effect then, the component being measured is the photosynthetic mass with a peri-.' 2 meter defined by a m plot. On average the procedure should give results comparable with those obtained from quadrats. ..The unpumped samples were collected in the former tidal channels of the Sturgeon Slough Marsh. Line transects were laid across the channels at four randomly selected locations. With the use of a steel tape five plots were located along each transect, one at each end and the other three spaced evenly between them. In wafer shallow enough to be waded the same procedure for clipping the vegetation as described for the ditches was used. Where depths exceeded A{ feet, an 8-foot punt was used to drop the frame into position and the vegetation was clipped and gathered with the aid of scuba gear. Upon completion of harvest-ing the sacks of submergent vegetation were transported to the University of B.C.,,where the material was dried, weighed, milled and stored in much the same manner as for the terrestrial and emergent vegetation. Materials were not run through the hammer mi I I;-Wiley milling was sufficient. The sampling of submerged aquatic plants was carried out during the. late summer of the 2 1972 field season. A total of eight m quadrats were harvested in the pumped area and 13 yielded.measurable vegetation in the unpumped area. 4.1.3 Chemical Analysis of Vegetation To obtain indications of trophic values, (viz. total N (crude protein) and total phosphorous) two methods were used. In 1972, approximately 80 mg 30. sub-samples of milled vegetation were placed in labelled, 15 x 85. mm test tubes. The samples were analyzed in a Technicon Auto Analyzer I I for total nitrogen, and phosphorous content. Analyses were conducted by technicians in the Agricultural Engineering Department, University,of B.C. Tests were performed on the Technicon Auto Analyzer II, according to techniques out-lined in the Industrial Methods section of the Automating Manual Methods. . In 1973, ana Iyses.were for totaI -nitrogen only, and were done in the Plant Science Department Laboratory using a modified semi-micro KjeIdahI technique according to Nelson and Sommers (1973). Crude protein of samples was in all cases determined by multiplying total N by 6.25 4.1.4 Collection and Chemical Analyses of Water Water samples were collected from each of the six habitat areas on four occasions:. (I) May, 1972, (2) July, 1972, (3) February, 1973 and . (4) May, 1973. Fifteen samples were collected on each occasion and each sample was then divided into three subsamples which were placed in labelled 250 ml plastic bottles. Two of the three, subsampIes were immediately fixed in the field, one by freezing and the other by lowering the pH by adding fuming H^ SO^  to give a pH of 2.0 - 2.5. Changes in chemical components by •bacteria micro-organisms were thus prevented, until the subsampIes couId be transported to the lab for further analyses. Tests for methyl orange a Ika-linity and pH were performed on the third subsampIe in the field because rapid changes in temperature, agitation, etc. bring about changes in these variables. Field measurements were conducted using a Hach Model DR-EL field kit. Tests for nitrate, total nitrogen and ortho-phosphate were conducted . on a Technican Auto Analyzer II. Tests for calcium were conducted using a Jarrel.Ash 82-270 Atomic Absorption Spectrophotometer. 31 . 4.1.5 Collection and Chemical Analysis of Soils The collection of soil cores in aquatic environments was f a c i l i -tated using a metal tube, 4 inches in diameter, and 6 inches long, with a perforated end. This end was perforated sufficiently to permit entrapped water to be' removed as the tube filled. The open end of the tube was placed against the mud - water interface and gently pressured downward with a twisting motion until the tube was completely, inserted in the mud. The tube, containing the sample core, was then removed from the substrate with the aid of a shovel placed beneath the core and the contents slid intact into a labelled plastic bag. Soil cores from terrestrial environ-ments were collected using a standard 6 inch soil sampler and these too were placed in labelled plastic bags. The samples were air-dried prior to chemical and texturaI analysis by technicians in the Soil-Science Lab-oratory at the University of B.C. A totaI of 23 cores were collected from four of the major plant com-munities, with two of these communities being sampled in both pumped and unpumped areas. Twenty cores were taken in the Public Shooting Marsh and the Sturgeon Slough Marsh. These were taken, along transects randomly sit-uated at right angles-to the old tidal channels in the marshes. This permitted measurement of changes in chemical and textural parameters with topography, which,, in effect, is measurement of these same parameters across communities. The first sample was taken in mid-channel and subse-quent cores spaced equidistant from this point to the immediate highest ground. The remaining sixteen samples were taken in and adjacent to areas of autogenic and allogenic successional activity in an attempt to monitor chemical changes occurring in either of two possible directions: 32. , (a) from a wild land grass and shrub stage to peat bog and (b) from wildland grass and shrub to reclaimed pasture. Determinations were Cl) % organic matter, (2) % nitrogen, (3) K, Ca and Mg, (4) Phosphorus and (5) pH. Determinations in (I) were made using a Leco Analyzer according to instructions in the Leco Manual. A semi-micro Kjeidahl technique procedures estabIished by Jackson (1958), was used to obtain total nitrogen. Potassium, calcium and magnesium determinations were made using methods outl ined in the Morgan Soil Testing System (Lunt, Jacobson, and Swanson,1958). The Bray extraction method • (J.ackson, 1958) was used to obtain phosphorus. 33. 4.2.0 Results and Observations 4.2.1 Cover Map The vegetation of the unmanaged lands of the Pitt Va.l ley occur in stands of both purity and considerable diversity. Though edaphic diversity may exert some influence on the overlying vegetation the past and present water regimes have been postulated (see Sec.. 4.3.4.) as the predominant', influence in this regard. A total of 22 non-forest communities were identified and incorpor-ated in. the cover map. These included the following: 1. Sc i rpus acutus 2. Sci rpus microcarpus 3. S^  microcarpus - Carex rostrata 4. Carex. rostrata 5. S_. microcarpus - Ca I amoqrosti s canadens i s - Sp i rea dougI as i i 6. 7. 8. 9. 10. C. canadensis - C. rostrata C. canadensis. Typha lati folia C_. canadens i s - S_. doug I as i i  doug las? i - C_. canadens i s Phalaris arundinacea 14. 15. 16. 17. 18. 19. 20. 21 . 22. S_. doug I as i i Sphagnum spp. - Myrica ga I e -Eriophorum chami sson is Sphagnum spp. - ML gaIe - Erio- phorum chami sson i s Sphagnum spp. douglasi i Carex spp, M_. gaIe - Ledum groenland icum Sphagnum spp. - C_. canadensis S_. doug I as i i - C. canadens i s -Sphagnum spp. .§.• doug I as ii - Sphagnum spp. M_. ga Ie - Sphagnum spp. - C_. rostrata 12. Egu i s i turn spp . 13. S_. doug lasi i - f_. arundinacea Collection of the major plant species of each community was under-, taken and subsequent to drying and identification, these were pIaced in the University of B.C. herbarium. . Many of the species can be described as cir-34. cumboreal and have been d e s c r i b e d i n N o r t h Europe. Such w i d e s p r e a d d i s t r i -b u t i o n a g a i n p o i n t s t o t h e c o n s e r v a t i v e n e s s o f w e t l a n d h a b i t a t s . The vege-t a t i o n c o v e r map of t h e P i t t V a l l e y i s l o c a t e d i n t h e a p p e n d i c e s (see Append i x I ) . 4.2.2 Dry M a t t e r Y i e l d s and N u t r i t i v e Qua I i t y o f S e l e c t T e r r e s t r i a l and A q u a t i c P l a n t Communities The y i e l d s o f t h e 1972 s t a n d i n g c r o p s and c h e m i c a l a n a l y s i s o f t h e samples a r e shown i n Tab Ie I V - I . On t h e a v e r a g e , t e r r e s t r i a l c o m m u n i t i e s produced t w i c e t h e s t a n d i n g crop, found i n emergent c o m m u n i t i e s and, seven t i m e s t h a t p r e s e n t i n submerged c o m m u n i t i e s . On t h e o t h e r hand, t h e ave r a g e p e r c e n t p r o t e i n was l e a s t f o r s e v e r a l t e r r e s t r i a l c o m m u n i t i e s and g r e a t e s t f o r t h e submergent c o m m u n i t i e s . T h i s t r e n d h e l d f o r phosphorus, c u l m i n a t i n g in a p a r t i c u l a r l y h i g h l e v e l i n t h e pumped, submerged v e g e t a t i o n . In g e n e r a l t h e amount o f n i t r o g e n p er u n i t a r e a i s h i g h e s t i n t h e t e r r e s t r i a l communi-t i e s and lowest i n t h e . a q u a t i c , as i n d i c a t e d by t h e pounds o f p r o t e i n p er a c r e per u n i t a r e a ( T a b l e I V - I ) . An e x c e p t i o n was t h e pumped a q u a t i c s , where t h e f i x e d n i t r o g e n p er u n i t a r e a was as g r e a t o r g r e a t e r t h a n t h a t n o r m a l l y found i n t h e emergent c o m m u n i t i e s . Samples o f v e g e t a t i o n g r o w i n g i n pumped and unpumped h a b i t a t s were c o l l e c t e d from one submergent, one emergent, and two t e r r e s t r i a l c o m m u n i t i e s . In each c a s e , t h e p r o t e i n i n t h e v e g e t a t i o n was g r e a t e r i n pumped t h a n i n unpumped a r e a s . S i m i l a r l y , t h e submergent and one of two t e r r e s t r i a l c o m m u n i t i e s produced a l a r g e r s t a n d i n g c r o p under pumped c o n d i t i o n s ; t h e e x c e p t i o n was t h e s p i r e a shrub community which produced 3,700 l b s / a c r e o f a e r i a l v e g e t a t i o n growing, i n an unpumped en v i r o n m e n t . V e g e t a t i o n o f both t e r r e s t r i a l c o m munities g r o w i n g i n unpumped a r e a s c o n t a i n e d g r e a t e r phosphorus t h a n t h e same community g r o w i n g i n a. 35. T a b l e I V - I : D r y M a t t e r Y i e l d s , P r o t e i n o f S e l e c t e d S t a n d i n g C r o p s a n d P h o s p h o r u s - 1 9 7 2 d r y l b s . C o m m u n i t y m a t t e r % p r o t e i n % l b s / a c r e p r o t e i n p e r a c r e p h o s p h o r u s T e r r e s t r i a l : Pumped P h a l a r i . s a r u n d i n a c e a 12,928 4.5 581 .8 .061 Unpumped P h a l a r i s a r u n d i n a c e a 12,803 3. 1 3 9 6 . 9 .085 Pumped S p i r e a d o u q l a s i i 16,182 2.5 4 0 4 . 6 .044 Unpumped S p i r e a d o u q l a s i i 19,849 2. 1 4 1 6 . 8 .052 E m e r g e n t : . . 3 7 0 . 6 . .131 Pumped T y p h a l a t i f o l i a 5,790 . 6.4 . Unpumped T y p h a l a t i f o l i a 4,047 5. 1 2 0 6 . ^ .126 Unpumped S c i r p u s m i c r o c a r p u s 5,353 4.8 2 5 6 . 9 . 129 Unpumped C a 1 a m o q r o s t i s c a n a d e n s i s . 7,735 . 4.4 3 4 0 . 3 .117 Unpumped S c i r p u s a c u t u s 5,808 6.2 360.1 .142 S u b m e r g e n t : 356.1 .588 Pumped a q u a t i c s 2,012 17.7 Unpumped a q u a t i c s 1,679 8.6 144.4 . 2 2 6 36. pumped a r e a . However, t h e most s t r i k i n g d i f f e r e n c e i n phosphorus c o n t e n t was found i n t h e submergent community where a q u a t i c v e g e t a t i o n i n pumped a r e a s c o n t a i n e d more th a n t w i c e t h e phosphorus p r e s e n t i n s i m i l a r v e g e t a t i o n of t h e unpumped a r e a s . In 1973, t h e d r y w e i g h t s o f c o m b i n a t i o n s o f new g r o w t h , o l d g r o w t h , and d u f f from t h e s e l e c t e d c o m m u n i t i e s i n c r e a s e d t h r o u g h o u t t h e s p r i n g and e a r l y summer (see T a b l e I V - 2 ) . Maximum v a l u e s f o r t h e f o u r month p e r i o d samp Ied genera I I y o c c u r r e d i n J u l y and August. An e x c e p t i o n was t h e pumped s p i r e a community which peaked i n June. By t h e l a t t e r p a r t o f t h e g r o w i n g season t h e combined d r y w e i g h t s o f t h e t h r e e f r a c t i o n s f o r t e r r e s t r i a l commu-n i t i e s were g e n e r a l l y g r e a t e r t h a n t h o s e from emergent c o m m u n i t i e s . In t h e two t e r r e s t r i a l c o m munities f o r which' v e g e t a t i o n from both pumped and unpumped a r e a s was sampled no d e f i n i t e t r e n d was a p p a r e n t . S p i r e a c o mmunities o f t h e unpumped a r e a s c o n t a i n e d a s u b s t a n t i a l l y g r e a t e r s t a n d i n g c r o p by l a t e sum-mer t h a n , d i d s t a n d s o f t h e same s p e c i e s g r o w i n g i n pumped a r e a s . '• C o n v e r s e l y , reed c a n a r y g r a s s g r o w i n g i n pumped a r e a s y i e l d e d a much l a r g e r s t a n d i n g c r o p by l a t e summer th a n d i d . s t a n d s g r o w i n g i n an unpumped e n v i r o n m e n t . In t h e one emergent community, namely t h e c a t t a i l community, f o r which samples were c o l l e c t e d i n both pumped and unpumped a r e a s , a much l a r g e r s t a n d i n g c r o p o f v e g e t a t i o n was p r e s e n t i n pumped s t a n d s t h r o u g h o u t t h e p e r i o d sampled, (see T a b l e I V - 2 ) . The c r u d e p r o t e i n p e r c e n t of t h e t h r e e v e g e t a t i o n f r a c t i o n s sampled d u r i n g t h e major p a r t o f t h e gro w i n g season a r e shown i n T a b l e IV—3. In both t e r r e s t r i a l and emergent c o m m u n i t i e s t h e new growth • t r a c t i o n g e n e r a l l y c o n -t a i n e d t h e h i g h e s t p r o p o r t i o n o f p r o t e i n e a r l y i n t h e growing season. In a l l c a s e s t h e d u f f l a y e r ranked n e x t . i n t h i s whereas t h e o l d gr o w t h , i n most i n s t a n c e s , c o n t a i n e d t h e l e a s t p r o t e i n p e r c e n t . By June, t h e d u f f o f t h e 37. Table IV-2: Dry Matter Yields of New Growth, Old Duff from Selected Plant Communities on Four Occasions During the Growing Growth and Obtai ned Season - 1973 Community May J une July August lbs/acre lbs/acre lbs/acre 1 bs/acre Terrestria1: Pumped Phalarisarundinacea 12,903 18,320 22,444 21 ,362' Unpumped Phalaris arundinacea 11,783 19,523 19,994 12,895 Pumped. Spirea douqlasii 28,957 32,650 28,593 29,319 Unpumped Spirea douqlasii — 30,478 35,877 37,612 Emergent: Pumped Typha latifolia 11,379 14,955 14,211 18,298 Unpumped Typha latifolia 8,762 8,054 9,636 10,732 Unpumped Scirpus microcarpus 14,337 13,402 16,154 1 1 ,966 .: Unpumped Ca1amoqrostis canadensis 10,382 17,398 17,683 16,689 Unpumped Scirpus acutus 5,663 7,792 8,638 38. terrestrial communities contained a greater proportion of protein than did the new growth fraction. This situation was maintained or gradually accen-tuated as the season progressed.. The same sequence occurred in the emergent communities. However, in those communities, new^  growth continued to exhibit a higher proportion of protein than the duff fraction until late July,, i.e. for a month longer than in terrestrial communities. In both terrestrial., and emergent communities, the protein percent of old growth remained lower than the other two fractions throughout the sampling period, and generally exhibited a slow decline as the season progressed. For the one emergent and two terrestrial communities for which samples were obtained in both pumped and unpumped areas the protein level of the.three fractions throughout the summer were considerably higher in the pumped communities. The totaI crude protein per unit area in the combined fractions (see Table IV-4) is a rough measure of the amount of nitrogen contained in the "aerial" segment of representative pI ant.communities. It was obtained by multiplying the yield of each of the new growth, old growth and duff frac-tions (see Table IV-2) for each monthly harvest by the protein percent of each fraction (see Table IV-3). In terms of total crude protein present in the three fractions, July would appear to be.the peak yield month for the study area as a whole. A comparision- of terrestrial and emergent, communities indicates that, with one exception, the former supports a greater standing crop of crude protein throughout the growing season that the latter. The exception was the unpumped reed canary grass community. In all communities, whether terrestriaI or emergent, for which pumped and unpumped samples were collected a higher crude protein content was indicated for vegetation from a p.umped environment. Similarly, within the unpumped emergent communities Table IV-3: Crude Protein Content of New Growth, Old Growth and Duff from Selected ' . Plant Communities Obtained on Four Occasions During the Growing Season - 1973 May June July August P A m m i i n i " f u New Old New Old New Old New Old oiwiMUNU i l l l y Growth Growth Duff Growth Growth Duff Growth Growth Duff Growth Growth Duff % .% % % i i i i * % % % Terrestria1: Pumped Phalaris arundinacea 19.2 7.4 1 1 .4 10.0 u 9.8 7.3 6.0 10.2 8. 1 5.7 9.2 Unpumped Phalaris arundinacea 9.2 4.4 6.5 4.5 2.7 .5.6 3.8 3.3 6.8 2.9 3.0 . 3.9 Pumped Spirea douqlasii 2.8 3.9 10.8 2.7 3.9 10.9 2.6 3.9 1 1 .4 2.4 3. 1 12.8 Unpumped Spirea douqlasii - - - — 1 .6 2.2 8.2 1 -5. 2.7 9.0 1.5 2.7 8.0 Emergent: 10.2 • Pumped Typha latifolia 1.4.0 4.9 9.7 9.6 . 5". 1 10.7 6.3 5.5 9.6 5.1 3:. 8 Unpumped Typha latifolia 14.2. 5.0 7.4 5.9 ' - 8.6 5.0 3.9 9.3. 5.3 2,7 7.8 Unpumped Scirpus m.icrocarpus 8.7 4.7 6.6 8.2 4.6 7.9 6.0 5.2 6.3 4.9 4. 1 7.2 Unpumped Ca1amoqrostis canadensis 9.7 2.7 4.8 5.5 4; 1 6.3 4.3 4.4 . 6.9 4.3 2.9 7.0 -Unpumped Scirpus acutus 8.4 2.9 7.2 5.7 3,6 6.0 6. 1 4.2 4.2 UJ VO Table IV-4: Crude Protein Present in. New Growth and Combined" Old Growth and Duff Fractions of Select Plant Communities During Growing Season - P i t t Valley, 1973 May June July August New . Growth . Old Growth . & Duff Tota 1 New Growth Old Growth & Duff Tota 1 New Growth Old Growth & Duff Total Old New Growth Growth & Duff Total Terrestria1: Pumped Phalaris arundinacea lbs./acre lbs./acre 1 bs./acre lbs ./acre 30.6$ 404. 1 69.4$ 915.8 1319.9 42. 3$ 695.1. 57.7$ 947. 1 1642. 2 41.6$ 715.1 58.4$ 1003.0 1718. 1 49.5$ .784.6 50.5$ 799.3 1583.9 Unpumped Phalaris arundinacesa 47.9$ 350.3 52. 1$ 380.4 730.7 43.2$ 355.9 56.8$ 467. 1 823. 0 46.3$ 366. 1 53.7$ 424.7 790. 8 58.8$ 229.4 41 .2$ 160.7 390. 1 Pumped Spirea douqlassi . 25.3$ 376.9 74.7$ 1110.1 1487.0 16.7$ 323.7 83.3$ 1611.9 1935. 6 18.2$ 297.5 81.8$ 134 1 .4 1638. 9 12.7$ 241 . 1 87.3$ 1656.5 1897.6 Unpumped Spirea douglassi - - - • 13.0$ 146.5 87.0$ 984.6 I 131 . 120.0$ 285. 1 . 80.0$ 1 139.9 1425. 0 32.7$ 337.9 67.3$ 695.0 1032.9 Emerqent: Pumped Typha latifolia 7.6$ 58.2 92.4$ 709.8 . 768.0-16.2$ 174.0 83.8$ 900.6 1074. 6 28. 0$ 256.7 72.0$ 658.9 915. 6 39.9$ 389.3 60. 1$ 586. 1 975.4 Unpumped Typha latifolia 7.5$ 40.0 92.5$ 495. 1 535. 1 -39.4$ 177.8 60.6$ 273.2 451 . 0 55.0$ 281 .2 45.0$ 230.3 51 1.5 Unpumped Scirpus microcarpus . 17.5$ 131 ,9 82.5$ 621 .4 753.3 27.2$ 208.7 72.8$ 559.9 768. 6 35.4$ 319.3 64.6$ 583.6 902. 9 19.2$. 115.4 80.8$ 484.3 599.7 Unpumped Ca1amoqrostis canadensis 25.8$ 1 19.6 74.2$ 344.2 463.8 26.5$ 218.5 73.5$. 605. 1 823. 6 21 . 5$. 183.2 78.5$ 669.5 852. 7 36.6$-251 .6 63.4$ 435.4 687.0 Unpumped Scirpus acutus -• -41.4$ 125. 1 58.6$ 177.2 302. 3 55.3$ 227.8 44.7$ 184. 1 411, 9 52.4$ 225.9 47.6$ 205.3 43| .2 * Percentage of total. -p. o 41. the species typical of long-term standing water, e.g. cattail and hardstem bulrush, tend to have a lower yield of crude protein than the emergents of shallower waters, e.g. bluejoint grass and. smaI I-fruited bulrush. Because much of. the nitrogen in old growth and duff is'organic nitrogen and is relatively unavailable to growing' pI ants and animals, readily available fixed nitrogen in systems such as those of the lowlands of the Pitt area is of particular interest and importance. Throughout the sampling period, in all communities sampled, the combined proportion of. these two fractions never dropped below 41.2 percent of the total crude protein present in any given community. In some communities, these fractions accounted for as much as 92.5 percent of the.protein present in the community. Though, definite trends are difficult to perceive, it appears that the pro-portion of. fixed nitrogen in unpumped communities by late summer is some-what less than in the.same community growing under pumped conditions. In terms of an . individuaI community, it would appear that, throughout the grow-ing season, both pumped and unpumped communities of hardhack "tie-up" the largest proportion of the protein.present in old growth and duff. This, coupled with, the large acreage of this species present in the pumped and unpumped areas, suggests that^'t is an important source of nutrient "short-stopping". 4.2.3 Water Regime and Quality By the end of the 1972 field season it was apparent that monitoring the fluctuation of water levels in the agricultural lands reflected the operating time of the pumps. Though fluctuations associated with rain and run-off occur quite frequently, their amp Iitude and'duration are such that 42. there appears to be little adverse effect on waterfowl or related components of their environment. Exceptions can occur; for example when an abnormally high spring freshet, in conjunction with high tides, reduces efficiency of the pumping. Then, a combination of seepage and heavy rainfall can result in fairly extensive short-term flooding. An entirely different situation occurs in unpumped areas where drain-age is by gravity flow. Weekly recordings of water levels in the Sturgeon. Slough Marsh-for'an 18 month period revealed.a definite chronological pattern (see Fig. IV-I). The pattern was similar in the unpumped southern extremity of the wiId land-associated with the marsh (see Fig. IV-2). Because of the difficulty in maintaining guage plates permanently, due to winter-ice action, weekly changes in water level (y-axis) are relative rather than an absolute measurement of water height. Despite repeated efforts to consistently moni-tor water, levels in the 565 acre Open Wildlands, vandalism and continual dam-buiIding by beaver often caused widespread disruptions in the normal sequence of water fluctuation. However, the area probably exhibits a pattern of water fluctuation similar to the aforementioned areas, albeit not so pronounced. Analyses of water samples from the various habitat types, reveaIed some well-defined differences in water quality between these areas (see Table IV-5). The differences are most apparent when comparing the water chemistry of the agricultural lands with those found elsewhere in the study area. A possible exception to this trend is the similarity of hydrogen ion concentration in the waters of the farmlands and those of the marshes. Waters draining the Open and_Dense wildlands display the lowest.pH and calcium contents of the six habitats under consideration. Conversely, the 31 v o. I h-0_ UJ O FIGURE IV- I : -CHRONOLOGY OF WATER L E V E L FLUCTUATION IN STURGEON S L O U G H MARSH-1972 &1973 1972 WEEKS-ENDING I JAN |43 F E B j43 MAR ^ APR WEEKS-ENDING —• ' . ' i » i ,, Ii i i a t i l < i n i i I • • I j u i | \ , | \ MAY |^ J U N E ^ JULY \ \ A U G | ^ S E P T \ 7 O C T \ \ NOV | ^DEC * 1 " * * " 1 » *, * • * • * • * • ' • * • • * ' • * • * • * * 1973 Comparison of water depth between years not valid due to difference in datum point. 4^ 44 FIGURE IV-2:- CHRONOLOGY OF WATER LEVEL FLUCTUATION JN STURGEON SLOUGH WILDLANDS AT FURTHEST POINT FROM GRAVITY-FLOW OUTLET-1972 &1973 3 ^ © 2 I CL UJ Q o H WEEKS-ENDING i i ' i II SEPT | 7 OCT | 4 NOV | 2 DEC 19 72 JAN u i i F E B * i i MAR | 7 APR | 5 MAY | 2 JUNE | 7 J U L Y | 1973 i r" i > AUG Ii "i—i—s—i—r 1 6 1 SEPT \ l T — t - T OCT | 3NOV 45. Table IV-5: Average Water Quality Data of Six Habitats in the Pitt Valley - 1972 and 1973 Habitat pH Alk. ^ ++ Ca. T.D.S. N 0 3 - N Tota1 N P O 4 - P • ppm Ag. 1 6 .8 3 8 . 7 4,46 345 .4 . 0 9 0 ' 1 .022 .015 Ag. II 6 .5 3 0 . 8 . 5 .94 254.-8 .250 1 . 1 12 .013 Open Wldld. 6 .3 8 . 6 1 .20 3 5 . 9 .020 . .606 .007 • Dense Wldld. 6.2 13.3 1,77 48 . 1 .050 .908 • .005 Sturgeon S1. Marsh 6.7 1 1 .7 2 . 9 9 62 .2 <.020 .458 .007 P.S. Marsh .6.7. 13.6 2 . 1 6 37 .3 <.020 .389 . .006 46. nitrate content of waters in the Ag. II area is noticeably higher than that found elsewhere, in the study area. 4.2.4 Soil Characteristics Five profile diagrams were constructed (see Appendix 2) to demonstrate edaphic changes in the marshes. From these, severaI genera I trends are apparent.. With one exception (see Diagram #4) the concentration of'calcium and magnesium increased as conditions became increasingly hydric. On the other hand, the phosphorus organic matter percentage, nitrogen percentage and H+ ion concentration decreased as conditions became increasingly hydric. There appeared to be no consistent trends in potassium. The exception allu-ded to above involved a transect restricted to one of the channels and con-sequently did not reflect, as other transects did, the progression from ter-restrial to aquatic conditons. A I though caIciurn and magnesiurn appeared to increase with profile depth the remaining parameters monitored showed no trend. DeI ineation of soiI conditions in two communities of the study area subjected to both controlled and uncontrolled hydrological regimes was generally inconclusive (see Table IV-6). Only organic matter percentage and nitrogen percentage, both of which were greater when the communities occurred ip unpumped areas, displayed any trends. The concluding phase of the soiI investigations is presented in Table IV—7. Comparison of the upper 20 inches of each profile reveals differences reflecting both long and short-term, influences of man on the soil and the vegetation. These are most noticeable when comparing the initial sample, layer of the profile with successive layers in the bluejoint, hardback and rough pasture samples. In the former two, the gradation of organic matter Table IV-6: Soil Characteristics of Two Common Plant Communities Subjected to Different Water Regimes - 1973 ... Community pH 4.50 4.70 % Organ ic % K Matter Nitrogen Ca. Mg ppm . •P Pumped Phalaris arundinacea Unpumped Phalaris arundinacea 16.46 .75 218.4 . 26.46 1.14 123.8 - . 83.1 172.1 25.0 18.1 Pumped Typha latifolia Unpumped Typha latifolia 5.20 4.70 4.41 .21 28. 1 5.01 .29 34.7 812.5 301.6 259.5 85.6 10.4 18.8 48. Table IV-7: Characteristics of Soils Supporting. Four-Different Plant Communities - 1973 Prof i1e Depth pH % Organ ic Matter % Nitrogen K , Ca ppm Mg : P Peat Bog: 0-5" 3.7 73.2 .75 540.0 1450.0 560.0 25.6 .. 5 - 6" 3.5 74.6 1.18 287.5 1 175.0 540.0 18.4 6 - 13" 3.8 58.8 .82 215.0 1850.0 630.0 14.8 13 - 19" 3.9 59.6 .79 90.0 1950.0. 570.0 1 1 .2 19 - 25" 3.8 64.6 .94 65.0 2550.0 . 600.0 8.2 Unpumped Bluejoint '." 0 - I I " 4.4 30.15 1.72 141 .3 763.0 298.8 . 14. 1 1 1 - 26" 4.9 7.22 0.35 1 1 .3 513.0 190.0 .2.3 Pumped Rough Pasture: 0 - 7" 4.7 7. 15 0.35 27.5 38.0 22.5 13.7 7-21" 4.9 4.03 0. 19 12.5 400.0 78.8 2.9 Unpumped Hardhack: 0 - I I " '4.7 24.5 0.93 87.5 25.0 ' ' 76.3 9.2 11 - 20" 5.2 1 .69 0.07 27.5 700.0 321 .3 2.3 49. percentage, nitrogen percentage and potassium percentage between these layers is of a much, larger magnitude than is found in.the rough pasture profiles of similar-depths. Conversely, almost all the chemical parameters measured in the successive profiles of the peat bog demonstrated a relative-ly homogeneous distribution throughout. 50. 4.3.0 Discussion 4.3.1 Cover Map The role of the vegetation cover map in wiIdIife management has long been .recognized (Dalke, 1937, 1941; Alexander, 1959). Such a map documents the vegetational status of an area at a given point in time thus serving as a basis of. comparison with similar maps constructed at a later date. In this manner both long- and short-term successional changes within an.area can be monitored, depending on the time interval between maps. In view of the planned modifications in the drainage patterns and water regime of the unpumped portions of the study area (Campbell, 1974) it is felt that the map prepared for this study will be of some management use in the future. Nevertheless, the obvious limitations of this map in interpreting all but the most drastic changes in short-term successional trends must be recognized. Therefore, it is suggested that future manage-ment of the area include detaiIed•cover mapping of those tension zones considered to be prime indicators of wetland successional trends, 4.3.2 Water Regime - Past and Present The history of water control in the study area has been detailed elsewhere, (see Section 3.2.0). Because of. its importance•to agriculture much effort is exerted-to maintain, by pumping, the water.table in the areas designated as Ag. I and II at a level conducive to good farm crop production. The efforts generally permit little surface water to appear on croplands or pastures from late April to late October. However, failures to keep the agricultural land free of standing water do occur. For instance,. . 5 1 . by June 14, 1972, one of the highest spring freshets since the flood year of 1948 backed up the waters of the Pitt and Alouette rivers for an extended period. Seepage through the dykes was extensive and the pumps were rendered unoperable by the high river levels. The result was the appearance, of sheet water whenever a depression in landscape occurred. In addition, many of the drainage ditches overflowed, spilling water onto the adjacent farm-lands, (see Fig. IV—3). This condition existed until June 21,. 1972, by which time a drop in the river levels permitted operation of the pumps. Within a 12-hour, period, the water table had been lowered sufficiently to effect removal of nearly all of the flood water. Though of short duration, this flooding was sufficient to kill or severely retard growth of several crops, notably corn. In addition, grasses of low-lying areas in several pastures were much reduced in vigour following flooding. Two weeks later a 36-hour rainfall occurred on July II and 12. The measured rainfall totals for those two days were 3.2 and 2.3" respectively. Despite operation of the pumps,during much of this time, flooding was extensive, and water covered a greater area than it did during the height of the freshet in June. However, within ,24 hours of cessation of rainfalI the water table had been lowered, to the point that it was confined' to ditches and sloughs. 11 , is unIikeIy that such instances of flooding during the growing season are common. In 1973, the spring run off of the. Fraser River system was near normal. Consequently, back-up of river waters in the study area , was much reduced in both magnitude and duration compared to.1972. Seepage was easily accommodated in the drainage ditches and readily removed by pumping. In.1973 rainfall was near the long-term average and posed little threat. The result was that no flooding of the agricultural habitats. Figure IV-3: Sheet Water on Farmlands of Ag. I. Resulting from Spring Freshet in Adjacent Rivers - 1972. 53. occurred during the late spring, summer and early fall months of 1973. During late f a l l , winter and early spring, the study area is subjected to heavy rainfall and the appearance of sheet water scattered over the farmlands is a fairly common occurrence. Nevertheless, even in winter, an extended period relatively low in precipitation, concomi-tant with pumping, soon restricts open water to ditches, sloughs and borrow pits. A much different water regime exists in the unpumped. habitats,, particularly the Sturgeon Slough Marsh and its associated wildlands. Twice a year,, in December and January and again, in June and July most, if not a l l , of the marsh and large sections of the adjacent wildlands are inundated. Water originates mainly as run-off from the mountain slopes at the eastern edge of the study area and, as such, its volume is largely dependent on the magnitude of rainfall. As can be seen from Figs. IV — I and 2, fluctuation in water level at a given point in this area can be as much as 3.5.feet over a 4 month period. Similarly, a rise of 1.4 feet over a 72-hour period was noted, after a 36-hour rainfall in mid-July, 1972. The only outlet for these waters is via gravity flow to a water pressure operated floodgate (see Section 3.2.0). This device, subject as it is to the vagaries of high winter and spring tides, the latter in conjunction with the' spring freshet, is often rendered , inoperabIe for long periods of time. This not only, permits a rapid build-up of flood waters, particularly after heavy precipitation, but also ensures their retention, often for weeks at a time. The recession .from the winter and summer flood peaks can be quite rapid, particularly in the case of the Latter (see Figs, iV—I and 2). The more gradual decline from the winter peak, accompanied as. it is by- several 54. minor resurgences,' reflects a combination of the high tides and moder-ately heavy precipitation characteristics of Spring in this area (see Table I I 1-2). Due to the very low water levels in the marsh by late August, the gun club leasing the area annua I Iy seeks to retain water by blocking the outflow culverts. Thus, the water regime for September and early October, as given in the curve in Fig. IV-I, has an artificial element. Although the Open Wildlands apparently undergo the same general pattern of. water fluctuation as the bulk of the unpumped areas, the peaks and troughs appear to be of a much lower magnitude. This may be due in part, to a change in surface.drainage patterns caused by the main north-south road that isolates this habitat type from the adjacent wildlands to the east. Within the last 100 years, the unpumped portion of the study area has experienced three distinct water regimes, a) a more or less natural regime prior to 1913, b) a period of attempted control for agriculture, 1913 to 1952 and c) the "gun club" control, 1952 to present. Prior to dyking in 1913 the study area, then known as the Pitt River Meadows, was drained by a myriad of sloughs and channels that u l t i -mately emptied into three major.waterways. These in turn emptied into one another, with the Pitt River ultimately discharging the combined waters into the Fraser River. Throughout much of the year this was the pattern of drainage with, of course, some modification due to the tidal influence of the Fraser estuary. Except for the marshes and other major depressions such as the sloughs and channels, the area was generally free of standing water throughout much of the"year. However, in mid-June of each year, the spring freshet of the Fraser and, to a lesser extent, the Pitt and the Alouette rivers, would inundate most of the study area with cold, silt-laden waters. Thjs undoubtedly would have, a profound effect on the vegetational pattern in the area (see Section 4.3.5). Such conditions would prevail for a relatively short time, perhaps 10 to 20 days. A return to near-normal . levels by the Fraser and its tributaries wouId reinstate the previously described natural drainage. Thus the pre-1913 flooding was largely a reflection of the Fraser River levels. This situation changed abruptly With the advent of dyking in 1913. Though too low (see Section 3.2.0) provide total protection during the peak of most freshets the dykes did limit some aspects of flooding. The flood waters now consisted of seepage through the dykes, wash-over the top at the freshet peak in some years, and run-off from the high mountain slopes, that form the eastern boundary of the-area. In total, it is unlikely that the height of these three components, in most years, came anywhere near the level of inundation reached at this time prior to dyking. However, pre-dyking floodwaters would peak and then recede fairly rapidly, via natural drainage. Now, the situation was created whereupon any water accumulated within the. dykes had to be removed artificially, either by pump or a gravity flow set-up. Neither of these, devices proved able to handle the volume of water involved (see Section 3.I.0). Hence, the water regime of the area, for this time of the year, was abruptly changed from one of complete, and often high-level, inundation for a short period in mid-June to usually lower level inundation for a month or more during June and July. The overall effect on the area was to increase the time the water table was above, or close to, the surface. At the same time, partial inundation lessened both the mechanical and the physiological injury to the more flood-sensitive vegetation. The aforementioned changes in themselves were of considerable ecological significance, but they were not the only effects of dyking. Prior to 56. 1913 winter rainfall and subsequent run-off from the adjacent mountain slopes to the east, though'substantia I, rarely affected the water regime of the lowlands. This reflected the low levels of the Pitt, Alouette, and particularly the Fraser.River, at this time of the year. This permitted a very rapid run-off of winter rains by way of the many sloughs and channels that ultimately empty into the river.. With the advent of dyking these waters were now enclosed within the dykes with the only exits being via the pumping station and the gravity flow culvert. The relative inefficiency of these has already been mentioned. The end result was that during much of the late winter, varying amounts of water were impounded over the . Meadows at a time when, prior to dyking, they were relatively dry. Therefore, if we look at the results of dyking on a year-round basis, it is apparent that the water table was now at, or closer to, the sub-stratum for a considerably longer period of time than in any given year prior to dyking. This water regime was perhaps typicaI of the study area from approximately 1913 to 1952. However, during time marked springtime f I ood i ng-occurred at least three times,, namely, in 1921, 1935. and 1948 (McDermott, 1967). On these occasions, inundation to levels found prior to dyking could be expected as the dykes were either breached or simply topped. One can conclude that such occurrences only served to further complicate the'ecological processes underway within 'the 'confines of the dykes. 4.3.3 Water Qua Iity ' Ca) Pitt Lowlands in the Regional Context The waters of the study area are located in the Lower Eraser Valley, one of 12 Iimnological regions of B.C. CNorthcote and Larkin, 1956). Lakes and streams that remain unmodified by man's activities, I.e. domestic, 57. agricultural, and/or industrial, are considered to be ol igotrophic or "nutrient poor". This is reflected in an average reading of 44 ppm T.D.S. (total dissolved solids) for six lakes in the region. On a province-wide basis, Northcote and Larkin (1956). noted a relationship between low T.D.S. levels and low production of phytopIankton, bottom fauna, and fish. The dissolved nutrients of a region generally reflect the geologic nature of the country'rock with some modification attributable to climate. Thus, Frey . (1963) attributed the relatively low T.D.S.. levels of coastal mainland British Columbia to the resistant granitic substrate and high annual rainfall that typifies the area. (b) Non-Agricultural Habitats Based on T.D.S. content, four of the six habitat types inthe study area would appear oI igotrophic in nature (see Table IV-5). Three of these, the Open Wild lands, Sturgeon Slough Marsh, and Public Shooting Marsh, re-ceive the bulk of the.i r water-as rainfall and run-off from the adjacent mountains. In addition, large amounts of nutrients in these areas may be held in un.decomposed vegetative matter due to retardation of oxidation pro-cesses (see Section 4.3.4).. These areas are also subject to periodic flushing action.via the gravity fIow out Iets.which undoubtedly results in loss of nutrients. The Dense Wild land, though located in a pumped area,' apparent!y.receives li t t l e circulation of waters from the adjacent agricul-tural lands. Its low T.D.S. level would appear to reflect the low nutrient content water from the rocky outcrop known as Green Mountain, and impoverishment of waters draining the peat deposits of the area. These depo-. sits.also apparently contribute a large amount of suspended or dissolved -humic matter, which result in the brown-staining of the water. This organic 58. matter may account for the higher total nitrogen in Dense Wild I and waters relative to those of the marshes. A simiIar•condition exists in the Open Wildlands and those waters also have a relatively high nitrogen content. + ++ The high H concentration and low Ca levels of these two areas reflects the peaty conditions in portions of both these habitat types. The high acidity reflects the "secretion" of H+.ions by Sphagnum spp.. and further formation,of acidic products on decay of the remains of sphagnoid mosses (Small, 1972). Low calcium levels in the water can be attributed to the highly colloidal nature of the organic substrate in peat bogs.which ++ readily removes Ca ions from circulation (see Section 4.3.4). (c) Agricultural Habitats In •comparison to the wildlands and marshes,'the waters of the agri-cultural sections of the study area appear almost eutrophic or "nutrient rich" in nature. Highly modified by land; reclamation and farming techniques, these areas no longer depend solely on natural sources for nutrient replen-ishment.. Instead, these sources are now suppIemented artificia I Iy by appli-cation of commercial fertilizers and animal excreta from dairy and beef cattle. Leached by the heavy rainfall of the area, many of these nutrients are flushed into the ditches and sloughs and subsequently pumped into the adjacent rivers. If not for the latter action the nutrient content of these waters would be even higher. Even so, the T.D.S. content of these, habitat types (see Table' IV-5) compares favourably with the 229 ppm average for 33 lakes in the Southern Interior Plateau (Northcote and Larkin, 1956). Ad-judged to contain large standing crops of aquatic organisms by the authors, this Interior area encompasses the bulk of the highly productive waterfowl habitat in the province (Harris - pers. comm.). 59. Another rough index of a water's productivity is its total alkalinity. A.measure of the carbonate content of. water, total alkalinity expresses the concentration of two important components, carbon dioxide and calcium. Low alkalinity, i.e. 40 ppm, has been associated with sparse growth of aquatic vegetation (Moyle, 1956). Although the total alkalinity of the farmland waters is substantia Ily greater than that of. the marshes and wildlands, it barely exceeds 40 ppm. Further investigations are needed to establish the exact relationship, if any, of. low a IkaIinity and production of aquatic vegetation and organisms in the study area. A final observation on relative nutrient levels in the two agricul-tural habitats concerns the concentrations of calcium, magnesium and nitrate nitrogen. Though the exact cause of the higher levels of these elements in Ag., II waters is unknown, drainage and seepage from four dairy barns withi'n this habitat type are undoubtedly contributing factors. 4.3.4 Soil Characteristics In Section 4.3.3, it .was shown that the waters of the unpumped portion may be classified as oligotrophic. This was, in part, attributed to the granitic origin of the adjacent mountains, where much of the water originates. However, it can also be taken to refIect.conditions in the grass and shrub communities adjacent to the marsh proper. This is especially so during. periods of low to moderately high water levels which permit considerable drain-age towards the low-lying marshes to the north. (a) Soil Characteristics Along a Mesic-Hydric Gradient The results (see Section 4.2.4) df a, series of soil samples in these uplands appear to show several trends which contribute to an impoverishment 60. •of • nutrients'. in waters draining these areas. Build-up of calcium and mag-nesium with increasingly hydric.conditions reflects the susceptibility of these two nutrients to leaching. Moving into the permanent waterways of the marshes by leaching of adjacent soil, much of the ionic material is undoubt- . edly flushed from the area and is effectively removed from the nutrient cycle of the marsh, and wildlands. The concentration of the calcium, in con-junction with the photosynthetic activities of submerged aquatics, probably accounts for the generally lower H+ concentrations found in the permanently submerged so i Is. The abrupt decline of organic matter percentage in most samples of permanently submerged soi Is. probabIy reflects several interacting factors. These include a lower plant yield per unit area than the adjacent terrest-rial and emergent communities, f.1 ushing, .and a more rapid rate of decomposi-tion of plant remains in the absence of large quantities of structural com-ponents (i.e. lignin and cellulose). . Converse Iy, the relatively higher organic matter content of the terrestrial and semi-terrestrial plant communi-ties reflects, in part, the long-term accumulation due to disruption of oxidation processes by annual flooding (Buckman and Brady, I960). Because the nitrogen percentage is dependent on the organic content of the soil (Gorham, 1953), it exhibits the same trend as organic matter. Similarly, soil phosphorus, with 45$ or 50%, generally considered to be organic, reflects the organic matter levels. However, there appears to be a.somewhat widerP:0.M. ratio in the permanently submerged soils. This may reflect, in part, luxury consumption by phytopIankton and greater availability to submer-ged aquatics due to a higher-pH. In addition, some phosphorus may be lost via outflow of water from the area. ' 61 . (b) Comparison of SoiI.Characteristrcs in Pumped and Unpumped Areas. Examination of pit profiles in pumped and unpumped areas revealed soil characteristics apparently related to both water regime and land management practices, i.e. ploughing. Where ploughing has incorporated organic matter into the underlying glei and conditions favouring oxidation develop, as, in the. rough pasture, the profile shows a silty clay streaked with organic matter. Both calcium and magnesium move downward to the silty non-organic clay Iayer•existing below the plough sole. However, in the adjacent unpumped soils, vegetated to stands of blue-joint and hardhack, a marked stratification is evident.. Typically, the top 7 - 8" of the' profile consisted of 3 - 4" of dark, partially decomposed organic matter overlying a similar thickness of dark, humic organic matter. This changed abruptly to a 2{u layer of light, rust-streaked, non-organic clay. . From I0|" to the glei layer at 26", the profile consisted of a grey clay which showed very fine streakings of root material. Such stratification apparently reflects a combination of the. much slower oxidation rate of organ-ic material in soils subject to periodic inundation and the absence of soil . structuring that results from ploughing. Similarly, the greater concentra-tions of potassium, calcium and magnesium (relative to. that found in the corresponding surface layer of the pumped soils)' reflect the greater colloi-dal surface ' presented by the accumulated organic matter (see Table IV-6). In this regard, the distribution of calcium in'.the soils underlying the hard-hack appears contradictory to the aforementioned conditions. Further inves-tigation is necessary to determine whether this deviation reflects field con-ditions or error in analysis-. The ultimate soil in the unpumped areas, where autogenic succession is not impeded, would be peat. Characterized by high 62. acidity and very high organic matter-content, peat also exhibits a very high colloidaIity due to the organic matter content and the particular type of hum.i f ion. This is reflected in the relatively large concentra-tions of calcium and magnesium and, to a lesser extent, potassiurn. (see Table IV-6). The. seeming'anoma Iy of high acidity and high calcium content is explained by the exceptionally high cation absorption capacity of peat. This permits the many H* ions readily available in the wet bog conditions to absorb onto the colloids, resulting in an overall low percent base sat-uration (Buckman and Brady, I960). 4.3.5 Succession of Vegetation There is virtually no evidence in the'Iiterature pertaining to the vegetational pattern in the study area prior to 1911. McDerrnott (1967) referred to the grazing of cattle and the making of hay in the lowlands of Pitt Meadows during the 1890' s. However, both these activities were restric-ted to after the spring freshets of the Fraser, Pitt and Alouette rivers. These observations suggest that a substantial acreage of the flood plain, consisted of grassy meadows. Aeria I. photos taken 17 years after the completion of dyking portray the area as a mosaic of dense shrub, (ma i n I y . hard-hack)' and grassy meadows (primarily bluejoint) and sedges (Carex spp.). The north-east area, encom-passing the drainage of Sturgeon Slough was a fresh-water marsh, prominently established to hardstem bulrush. At least five areas of active bog formation are di scern i bIe. (a) Vegetative Cover Prior to Dyking Had it not been dyked, one is forced to postulate as to the eventual climax vegetation of this area, qualifying known ecological processes with 63. local environmental parameters as they existed at that time. In this case, the recognized successional sequence from freshwater marsh-meadow-shrub-bog-forest was undoubtedly in progress but was in all probability retarded in its advance by the highly variabIe -water regime of the area, (see Section 4.3.1). Rigg (1925) states that the large Pitt peat bog approximately 4 miles south of the study area originated as a. shallow fresh water marsh. Profiles in the bog just west of Burnt Mountain showed an abrupt change, at the 4 m level, from an upper fibrous peat horizon to a muck horizon inter-laced.with s i l t and humified swamp-reed. These instances of study support, the view that succession proceeds as given in the marsh-to-forest system previously mentioned;. .The most important factors, when considering the pre-dyking successional patterns, were the daily and seasonal water fluctuations. The effects of flooding on vegetation can be two-fold: I) a large quantity of suspended material is. deposited in the area, and 2) the light penetration during and immediately after flooding is greatly reduced (Van der Val.k and Bliss, 1971). A heavy deposition of s i l t can result in a physical burying of. some plant communities, whereas the reduction of light due to suspended particles greatly effects the survival capabilities of certain communities under the stress of inundation. On the other hand, some communities are physiologically able to withstand extended periods of inundation with little or no i l l effects (Brink, 1954). Thus floods can temporarily reverse successional trends (Lippert and Jameson, 1964). In such instances it can be said that the suc-cessional pattern is progressing rhythmically rather than linearly and, fig-uratively speaking, can be said to be taking three steps backward to advance four (Van der VaIk and Bliss, 1971). . . 64. Taking many uncertainties into account, we can postulate that much of the study area, prior to dyking, saw a gradual encroachment of shrub over both the meadow and marsh areas during years of low or normal spring flooding. The trend might be reversed or impeded during the periodic years of exceptionaI Iy heavy run-off and flooding, such as occurred in I 894. It is probable that the annual flooding was not unduly detrimental to the established peat' bogs. However, RIgg (1919) states that poorly-drained habitats, no matter how attractive, do not become bogs unI ess.Sphagnum spp. can become estab.I ished to the point that these form a surface mat underlain by various stages of decaying vegetative matter. Sphagna are a light-demand-ing species' (Turreson, 1916) and are capable, of growing in shallow water of up to 18" in depth (Rigg, 1919). However, it is suggested that a prolonged period of inundation by silt-laden waters and the accompanying light reduc-tion could severely retard the vertical.and horizontal advances of the Sphag- num mat. Hence, a rhythmical successional pattern similar to that found in the younger successional stages of the area could be expected in the peat bogs under such a water regime. The rate of Sphagnum colonization may also have been retarded by the fairly rapid drainage that occurred in the Meadows prior to dyking, excluding, of course, the freshet period (see Section 4.3.1). For example, Rigg (I9|9), in his discussion of a hardhack swamp at Covington, Washington, stated that although conditions for bog formation (i.e. Sphagnum species and lack of drainage) were present, no bog situation yet existed. The swamp was free from standing water for no more than three months of the year. None-theless, the author states "The fact that the area is dry in late summer... undoubtedly was a factor in. the rather slow growth of the Sphagnum...". 65. There is little doubt that the ecological factor exerting a very great influence on the Pitt River Meadows prior to 191 I was the water regime. It is logical to expect therefore that any change or modification in the water regime of the area would reflect changes or modifications df the successionaI patterns of the vegetation. The construction of dykes around the. Meadows and the. Installation of pumps within this enclosed area resulted in a drastic change in both the daily and seasonal water regimes (see.Section 4.3.1). (b) Vegetative Cover - 1911-1952 There is little in the way of pictures or documents so far found for. the 1911-1952 support or sustain any particular line of argument as to the successions in the Pitt Polder area. The area has been aerially photographed three times in 1930, 1940 and. 1952. However, the poor resolu-tion and scale of the photos of 1930 and 1940 make a sequential comparison of vegetational patterns unreliable. Some assistance in interpretation is obtained from accounts of.successionaI patterns, in similar habitats else-where. These are supplemented by personal communicat ions, with long-time residents of the area. The most significant change affecting the vegetation during this period was the change in the water regime. The reduction in peak flood level, in conjunction with the generally wetter conditions now existing on a year-round basis, could be expected to be reflected in a far more rapid and direct progression towards bog or bog forest. The predominant shrub of the area, hardhack, ..thrives under similar conditions in bogs throughout the Pacific Northwest (Turre.sson, 1916; Rigg, 1919, 1925). At Covington, Wash., Rigg (1919) described an area of shrub swamp in which the hardhack bushes, 66. averaging 5 - 10 ft. high, formed impenetrable thickets. It is noteworthy that the water regime in that swamp was such that the area was free from standing water for only three months of the.year. Thus, based on the appar-ent vigour of hardhack stands growing under similar edaphic conditions else-where we can postulate with some confidence that,the hardhack stands in the dyked areas would flourish and, in the. process, expand their boundaries at the expense of the neighbouring meadow communities. The cycling of nutrients within the dyked area was disrupted in. two ways. First, the input of s i l t and eutrophic waters from the mix of. the Fraser, Pitt and Alouette rivers was sharply curtailed. Second, the colder, wetter conditions of early summer now found in the area, coming as they did during the period of maximum biological degradation of organic mat-ter at this latitude, resulted in a slow-down in the oxidation of vegetative components from previous years' growth. This not. only tied up nutrients in the undecomposed material (see Section 4.3.5) but a I so.permitted the estab-lishment, of such aquatics as Buckbean (Menyanthes trifoliata), smartweeds, (PoIygonum spps.) and Marsh Cinquefoil (PotentiI la palustris). These plants form,dense tangles or "mats" of vegetation thus shallowing marsh areas and providing a base for eventual invasion by shrubs (Turresson, -1 91 6). After a period of time, sufficient consolidation of the mat would occur so as to permit development of the shrub stage, represented in the main by hardhack and Sweet Gale (Myrica gale). In keeping with the established successionaI pattern for shrub-swamp communities at this latitude (Turresson, 1916; Rigg, 1919), the more advanced of these areas were soon invaded by Sphagnum spp. The role of these species in bog mat-formation has been well documented (Rigg, 1916; Potzger, 1934). Thus, this phase of reclamation was, 67. for.the most part, characterized by an expansion of the shrub swamp stage at the expense of the marsh and meadow stages. . '(c)- Vegetative Cover from 1952 to the.Present Comparison of the area of lowlands receiving run-off from adjacent mountains prior to 1952 to the area presently utilized in this manner indi-cates a. change • in'spa-tia I distribution of water since that date. If consi-deration is restricted to the area north of Ladner Road (see Figure IV-4) it is apparent that the same area of watershed is discharging run-off into an area approximately 35$ smaller than the situation prior to 1952. Under these circumstances sI ightIy wetter conditions have probably existed, in the bulk of the gravity flow area since then. However, a comparison of aerial photos taken in 1949 and 1973 indi-cates that the successionaI trend postulated for the period 1913-1952 is continuing. Though general throughout the gravity flow area, this trend is particularly evident in two locations. The first is a, former channel of Sturgeon Slough which f.lows 'diagonal ly across the wildlands, just north of "the Knoll". In 1949, much of. this channel was an open water area bordered by sedges and cattail (see Fig. IV-5). By 1972, cattail had, in many places, extended from, bank to bank, albeit sparsely in the deeper, centre portion of the channel. Mat-forming aquatics, particularly Marsh Cinquefoil, are evident along.much of the shallowed portions of the channel, in places forming.dense entanglements of vegetation. Adjacent to the slough, thickets of hardhack now extend into what were, in 1949, stands of bluejoint and, sedges. A continuation of present hydric conditions would probably see the elimination of this slough as a water body in the relatively near future. A similar trend is apparent in the extensive acreage of peat ponds (see 69. FIGURE IV-5'.-SUCCESSION DURING 24 YEARS HAS RESULTED IN A REDUCTION OF OPEN WATER AREAS OF MANY SLOUGHS (A). ALSO NOTE ENCROACHMENT OF SHRUB COMMUNITIES ON GRASS AND SEDGE MEADOWS (B). 70. Fig. IV-6) immediately north of Burnt.Mountain. Many of the smaller ponds have been eliminated since 1949 and the remainder reduced in size (see Fig. IV—70. Succession in this area is more advanced than in -the slough previous-ly discussed, Thus, the incoming vegetation is ericaceous in nature and reflects the developing bog. The early stages of bog succession can also be noted by comparing areas of hardhack adjacent to the peaty ponds in 1949 with the same areas in .1972. By the latter year many of these stands had been greatly reduced in size, reflecting their invasion and subsequent des-truction by Sphagnum (Rigg, .1919). An even earlier successional stage is .evidenced by the changes undergone during the past 20 years by the. two sloughs north and northwest of the peat ponds. The.former, already partially filled by emergents in 1949, is now completely obliterated as a water, body, its for-mer course marked solely by a meandering stand of sedges. The second slough, though s t i l l showing patches of open water in 1972, is also greatly reduced in water surface area due to rapid colonization by mat-forming aquatics and sedges (see Fig. IV-8). Although the successional trend throughout most of the'area is towards bog, and seres are in evidence throughout, a number of isolated bogs have apparently been established for some time. In and around some of the bogs a later stage in the succession is in evidence viz. the bog forest. In the study area, such forests may consist of both coniferous and deciduous species. The most common conifer is Lodgepole pine (Pinus contorta), a common invader of old bogs at this latitude (Rigg, 1925). In the last 20 years this species has been particularly successful in colonizing the peat bog between Rannie Road and Burnt Mountain. Western birch (Betula occidental-is) is the most common deciduous tree. It is particularly prominent along the western edge 1949 1973 FIGURE IV-6: -0PEN WATER AREAS OF PEAT PONDS (A) AND SLOUGHS (B) NORTH OF BURNT MTN. HAVE BEEN GREATLY REDUCED BY SUC-CESSION. F i g u r e IV - 8 : E a r l y A q u a t i c S u c c e s s i o n Showing E x t e n s i o n of Emergent Sedges Zone a t Expense of Open Water A r e a s . of bog. in the Open and Dense Wi I'd. I a nd habitats. The presence of bog-forest there may reflect its proximity to the borrow pit and the subsequent improve-ment in drainage in the immediately adjacent area. Rigg (1922; 1925), in describing peat bogs of the Puget Sound area, noted that Western Birch was a successful invader, particularly where drainage had improved. In addition, however, there'are many . indiyiduaI birch scattered through these older bogs and this may well reflect natural succession. The presence of Cotton. Grass (Eriophorurn spp.) in conjunction with the birch would tend to support this view for Cotton Grass is indicative of the elevated, drier conditions con-commitant with aging in bogs (Turesson, 1916). In the approximately 800 acres of Sturgeon Slough Marsh,the rate of succession appears inversely related to the permanency of standing water. Hence, a comparison of vegetative change from 1952 to 1972 indicates the greatest progression in the f o I low i ng commun i t ies: (a) S_. mi crocarpus -C. rostrata, (b) S. microcarpus, Cc) C. rostrata, and. (d) S_. mi crocarpus -C. canadens i s - S_. doug I ass i (see Appendix I ). Significantly, all of these communities are characterized by large annual additions of organic matter in the form of dead- and dying foliage. These deposits, aided by flood-slowed oxidation processes, accumulate in significant amounts, shallowing the general area. Gradually, such conditions could be expected to stimulate the invasion, by the more mesic plants of the shrub swamp. However, consid-ering the apparent suitability of conditions for rapid succession to occur here, the overall progression appears somewhat retarded. Further investiga-tions may relate this to the duration and depth of flooding. Within the deeper portions of the-marsh there appears to have been little change in the spatial distribution of existing emergent communities in the last 20-plus years. Vegetated largely by hardstem bulrush these areas 74. contain standing water of varying depths:for most, if not a l l , of eac,h year. This may well contribute to the more static successional trends encountered. A similar situation apparently exists in the 582 acre Public Shooting Marsh whose emergent vegetation also, consists largely of hardstem bulrush (see Appendix I). Though a definite fluctuation in water level has been estab-lished in this marsh (Gates and Caverhill, 1969) it does not appear to be as.drastic as'that .occurring In the Sturgeon Slough Marsh. This, and the marsh's more recent origin, may account for the relatively monotypic vege-tation encountered there. In conclusion, the overall trend in vegetational succession within the habitat types subjected to gravity-flow drainage is from a marsh-wet meadow complex to a shrub-swamp-bog environment. This process can be expected to continue in the foreseeable future, assuming no major change in the hydrology of the area occurs. From a physiographic standpoint, the amount of year-round surface water in the area will continue to decrease as ponds/ditches, sloughs and former channels are shallowed and filled. Based on the rate of such processes during the period 1952-1972, this can be expected to occur in the relatively near future. At that point in time, year-round water will be restricted to the major channel systems and the deeper portions of the marshes. These latter would essentially be the central portions of the existing hardstem bulrush communities (see Appendix 1). 4.3.6 Yields and Proximate Analysis of Selected Plant Communities It was beyond the scope of this study to present a detailed investi-gation of production and proximate analysis of vegetation. Rather, my approach was to establish some baseline data to guide early management deci-sions. It was hoped that from the data, lines of further investigation might be delineated. My approach enabled, sample a maximum number of plant communities. Thus, the following discussion of the results and observations, presented in Section 4.2.2 is offered, keeping in mind the objectives sought: ' (a) Standing Crop Estimates: A single standing crop determination, as was utilized in 1972, has certain shortcomings (Penfound, 1956; Westlake, 1965). NevertheI ess,, two important features pertaining to the yield and quality of vegetation in the Pitt Valley are .indicated. The first of these indicates, in general, that yields of standing crops of the Pitt area increase with .hydrarch succession, i.e. submergent > emergent > meadow > terrestrial communities. Similar trends with respect to submergent and emergent communities have been noted in other investigations (Westlake, 1965; van der VaIk and.Bl iss, I 972). However, these authors generally terminated their sampling in the meadow stage of succession. At that point, standing crop was declining from the maximum reached in the earlier emergent communities. My findings would indicate that,, in the Pitt Valley, standing crop increase with hydrarch succession up to and including the shrub stage. Based on the postulated successional pattern for the area (see Section 4.3.5), this would indicate that the study area will be supporting a progressively greater standing crop of vegetation with time. Yields of standing crops of bog vegetation do not, in all probability, conform to this generalization. That the generalization has significant ecological implications is indicated by the trend in nutritive quality of communities sampled in 1972, viz. there is an inverse relationship between crude protein and standing crop. This agrees, with Polisini's (1972) findings that, in progressing from species with low to species with high standing crops, there is an increase in cell-wall material and a corresponding decrease in apparent digestibility and nitrogen content. This supports the contention that the trend in the undev-. eloped lands of the study area is towards production of large standing crops of vegetation of decreasing quality. Nevertheless, because of.the large yield of communities of high standing crop, greater amounts of the organic nitrogen are "tied up" per unit.area than in low standing crop communities of high prctein,content. Assuming a continuation of present successional trends in the undev-eloped areas,, it is predicted that the two major influences on the cycling, of nutrients in these.areas will be (I) an increasing amount of the available nutrients, particularly nitrogen., "tied up" in vegetation of low nutritive value to consumers and (2) that these nutrients will be recycled at a much slower rate due to the "resistance" of vegetation with a large amount of cell-wall material, or high C/N ratio, add to decomposition. The result will accentuate the already oligotrophic nature, of "undeveloped" lands in the Pitt Valley. (b) Organic Matter Carry-over: Standing crop is used to measure erect or aerial vegetation in a; community and therefore is primarily a measurement of the current year's growth. However, the approach fails to indicate the amount of above ground organic matter that a community annually contributes to its environment, or when it is contributed. In terms of nutrient cycling, this can be of con-siderable importance, particularly where environmental conditions-dictate ' large accumu of old growth and duff,••'.such conditions apparently exist in a large portion of the study area (see Section 4.3.5). 77. In 1973, a sampling scheme (see Section 4.2.2) that sequentially sampled the above ground organic matter of a community, in terms of new growth, old growth, and duff, was instituted. A rapid spring and early summer increase of these three fractions combined, culminating in a July or August peak, appears typical of most communities in the study area. Such a trend close Iy. para I IeIs that established for conventional standing crop determinations in other investigations (Westlake, .1965; van der VaIk and Bliss, 1972). This suggests that the current year's growth is primarily responsible for the month to month variation. However, perusal of the monthly totals of each fraction indicates that both duff and old growth organic matter also undergo considerable change throughout the growing season. A more detailed study would be necessary to account, with certainty, for the temporal variation in standing crops. Jervis (1969), suggesting that seasonal variation in production pro-bably varies with species, attributed translocation of stored one cause in marsh vegetation. The same author also stated that availability of water throughout the growing season undoubtedly affects the production pot-ential of a marsh. This may well account for variations in standing crop and period of peak production in communities sampled in both pumped and unpumped environments. A final factor that must be considered is the relatively greater fertility of waterways (see Section 4.3.2) in the agriculturally-based pumped areas. This would apply particularly in the case of such species as cattail which have access to these enriched waters. (c) Crude Protein Trends in Current Year's Growth: The decline, from spring to late summer, in new growth crude protein percentage of both wild and cultivated plant species has long been recognized 78. in the literature (Stoddart and Smith, 1955; Reid, 1962). Though generally attributed to a gradual dec I ine ' in-protein and an increase in fibre and nitrogen-free extract, several additional causes have been suggested for vegetation of marsh environments. Keefe (1972) implied a form of luxury consumption, when she suggested that high nutrient content in the spring may result from uptake and storing of nutrients for use later in the growing season. Some elements, particularly nitrogen, phosphorus, and potassium are known to be taken up early in the growing season at a greater rate than later (Boyd, 1971). The ..same author suggested that removal of nutrients early in the season by a given community gives it a competitive advantage over phytopIankton and other macrophytic communities. This can be of part-icular importance in oiigotrophic waters, such as occur in much of the study area, where the supply of available nutrients is limited.' (d) . Crude Protein Trends in Organic Carry-over: The seeming anomaly of increasing crude protein content of old-growth, until mid-summer in'the emergent communities may be partially attributable to the high water levels present at that time. Though this would result in the leaching of easily removed cations and phosphorous, nitrogen may be retained to a greater extent. Thus, the proportion of nitrogen present in the.old growth may increase even though the net amount remains relatively stable or decreases slightly. During August, a drop in water levels permits oxidation processes to resume, resulting in a decline in nutrient content. This latter situation is more typical of conditions in the terrestrial com-munities and is reflected in the slow decline throughout the period sampled in those communities. (e) Crude Protein in Duff Fraction: 79. In comparison to the new and old growth fractions, there is relative-ly little seasonal change in crude protein content of duff in the various communities. Month-to-month variations in specific communities may be attri-butable to both environmental conditions and differentia! microbial popu-lations and activities. With respect to the latter, Odum and de la Cruz (1967) reported, that solubilization and/or metabolic utilization, of consti-tuents other than protein, by the microbial population can increase the' percentage of nitrogen with' time. Other workers (Kaushik and Hynes, 1968; Boyd, 1970b)•'have noted an increase in the absolute guantity of nitrogen in a specified unit of decomposing vegetation. This they attributed to a microbial synthesis of protein above that originaI Iy present. This may well account for the overall increase in crude protein content, from May to Aug-ust, in five of the nine conditions monitored. The end result of the aforementioned .vari at ions-'i n protein content with time is that by mid-summer, the duff of most communities has the largest percent protein. Reflecting the rapid seasonal elaboration of structural components, this condition in terrestrial communities is reached in June, approximately one month earlier than occurs in emergent communities. Delineation of July as- the peak month in terms of nitrogen. content reflects a combination of increasing standing crop and a s t i l l fairly high . protein percentage overall. However, as suggested earlier, the data indi-cate that the greater yield per unit of terrestrial communities permits them to support a I arger, amount of crude protein over the course of'.the growing season than emergent communities. The propensity of. both terrestrial and emergent communities in pumped areas to produce a, larger amount of crude protein than their counterparts in unpumped areas reflects the larger stand-ing crop and higher protein percentage found in the former environment. 80. Further study is necessary to determine the exact cause(s) of this disparity. (f) Significance of Organic Carry-over and Duff Accumulation: Perhaps the most significant results of the 1973 sampling scheme, at least from a habitat management standpo.i nt, can be found in Table IV-4. There can be little doubt.that the removal of such a large amount of nitrogen, as old growth and duff, from rapid recycling has considerable impact on the overall productivity of the area. This can best be illustrated by analogy. Virgin tall grass prairie, in the absence of fire and grazing, undergoes a simi Iar buiIdup of dead organic matter. Rice and Penfound (1954) measured the primary productivity, under such circumstances, at 3,060 lbs/acre. Ploughing of this prairie increased the standing crop to 4,639 lbs/acre! A further increase in primary productivity, to 5,656 lbs/acre, was realized when ploughed prairie was subsequently mulched. Thus, by promoting rapid oxidation of accumulated organic matter, and in the process releasing "tied up" nutrients, primary productivity was almost doubled. The implications, with respect to the study area, are obvious! It was stated earlier (see Section 4.3.4) that the successional trend in undeveloped portions of the study area were from marsh and meadow communi-ties to shrub (primarily hardhack) swamp. A further observation, based on the results of the 1972 vegetation analysis, suggested that.this would result increasing amount of nutrients being "tied-up" in vegetation of low nutritive value. To just what extent this would occur is further empha-sized by considering data presented for hardhack in Table IV-4. These indi-cate that, over the major part of the growing season, roughly 80 per cent of the above/ground nitrogen in this community is present as old growth and duff -r the two fractions already shown to be primarily responsible for nutrient 81 "short-stopping" in the study area. One cone Iudes .that maintenance of. the status quo, as it pertains to vegetationaI succession in the undeveloped areas of the Pitt Valley, will result in an accumulation of organic matter low quality vegetation for most fauna and an increasingIy steriIe land and. unproductive environment. 5.0.0 AQUATIC INVERTEBRATES 5.1.0 Materials and Methods 5.1.1 Sampling Techniques During the 1972 field season two methods were used to establish the quantity and the diversity of the aquatic invertebrates of the study area. The first method utilized a Wilding or stovepipe sampler as described in 13 Ed. Standard Methods of Sewage and Waste Water Analysis (1971). The mode of.operation was as follows: The sampler was plunged vertically downward into the substrate isolating a segment of the mud-water interface and a column of water up to 35 inches height. A stirring rod was used to lightly agitate the mud surface and the water column and the contents of the sampler, including any submergent or emergent vegetation, were then-quickly baled into a bucket. The samples were sorted and all invertebrate organisms found were preserved in 10% ethanol. The second method utilized in 1972 involved using a 6{ inch x 10 inch 2 aquarium dip net (mesh size = Imm ) to sample invertebrates located on, above or just below the water surface. At the sampling location, the net was placed in the water t i l l approximately one half the frame width was immersed. The investigator then rapidly pulled the net, maintaining this position, through a 5 foot arc. Upon completion of the sweep the net was removed from the water, any trailing vegetation quickly placed in the net and the mouth of the net then sealed to.prevent winged insects from escaping. These latter were then sorted from the net using surgical tweezers and placed in a labelled specimen jar containing the required preservative. The contents 83. of the net were then dumped in a white sorting.pan, the remaining inverte-brates located and then placed in the specimen jar for subsequent identifica-tion. Although efforts were made to restrict the period of sampling to coincide with the height of the brood season, severe flooding extended col-lections over a three-week.period in June. After reviewing the data collected in 1972 it was decided to change the sampling strategy in 1973. One change involved limiting the sampling to two major habitat types, the agricultural lands and the Sturgeon Slough Marsh, thereby permitting a relatively large number of samples to be taken. A total of 78 samples were collected from the farmlands and 75 from the.marsh area. It was hoped that this increase in sample size would permit a. more representative-comparison of invertebrate yield in areas of relatively high and low waterfowl productivity than was possible with the limited data col-lected in 1972. Sampling was conducted on June 2 and 3, with similar clima-tic conditions existing on both days. The choice of these dates was also timed to coincide with the chronology of the hatching season and thereby duplicate invertebrate availability to ducklings as nearly as possible. The method of sampling was also changed in 1.973. Use of the stove-pipe sampler was discontinued and all sampling was conducted with a dip net on the assumption that this device samples only that portion of the inverte-brate standing crop immediate Iy avaiIabIe to ducklings, i.e.those organisms at, or immediately above and below, the surface. During both field seasons the manner of locating sampling sites was the same. This involved randomly marking sites, on a 1,000 foot to the'inch air photo of a given area and then locating that site in the field. The techniques and equipment used in 1972 for sorting and preparing samples for subsequent identification were also employed in 1973. 5.1.2 Identification and Standing Crop Determination To facilitate identification, the contents of each specimen jar were emptied into a smaI I plastic sorting dish. Using a (Cenco) Stereo Microscope (I0-30X {Model 620901-2}) identification to family was made, where possibIe, and the name and number of organisms in each family entered on a data sheet. Unidentified organisms were segregated in IabeI Ied speci-men vials and sent to the Plant Science Department .at the University of British Columbia or the Biosystematic Research Institute in Ottawa, Canada, for identification. To determine the standing crop of invertebrates, all the specimens from a given habitat area were aggregated in separate jars according to family. The contents of each jar was then placed onto absor-bent,paper and the paper and contents agitated gently to facilitate removal of excess surface moisture derived from the preservative. The organisms were then quickly placed on a Mettler Type HI.6 80 gram capacity balance and the weight recorded to the nearest milligram. The surface area of water sampled per habitat area was calculated and the standing crop of inverteb-rates in.that habitat area was then expressed in pounds per acre (lbs/acre). 5.2.0 Results and Observations . 5.2.1 Standing Crop and Diversity in Habitat Types (I) 1972 Samp ling Due to the. small and variable sample size collected in 1972 the results were considered merely as indicators of an area's invertebrate capabilities rather than as a definitive statement on diversity and pro-ductivity. The results for each of the two sampling methods used are listed in Table V-I. The most noticeable difference in results between the two methods is the pounds per surface-acre for the same habitat area. This reflects the much greater surface area per dip net sweep as opposed to the relatively small surface area encompassed by each stove-pipe sample. The .difference between the two methods in the relative standing crop rank-ing of most areas is probably due to the variation in water strata sampled. Some observations on the respective methods follow: Dip Net . . . . There were an average of 21 families per area sampled, ranging from 27 families in Ag. I to 15 families in the Pub Iic Shooting Marsh (see Appendix 3). With the exception of the Pub I ic Shooting Marsh, the undeveloped areas . of marsh and wildland yielded a considerably greater standing crop than did the developed farmlands. Much of this difference reflects both the greater proportion and size of Molluscs in the samples from the farm areas. Other investigators (Sugden, 1973; Chura, 1961) have shown that Diptera, Hemiptera and Coleoptera contribute substantially to the duckling d.iet. Ag. I, Ag. II and Open Wildlands contained a greater number of families with the orders diptera and coleoptera than in the other,habitats sampled. With 86. Table V-l: Number of Families and Yield of Invertebrates in.the Six Habitat Types as Revealed by Two Methods of Sampling -. 1972 DIP NET STOVEPIPE No. Samp 1es No. Fami1ies Stand i ng Crop lbs. Surface-Acre / No. Samp 1es No. Fami1ies Stand i ng Crop . 1bs./ Surface-Acre Ag. 1 12 27 2.01 12 21 32.90 Ag, II 8 21 2.83 8. 19 8.05 Open Wi1d1ands 9 26 • 4.60 9 16 38.90 Dense Wild 1ands 6 1.8 4.33 6 13 53.50 Sturgeon S1. Marsh 1 1 17 4.57 1 1 I7: 1 1 .20 P.S. Marsh 7 15 1.14 7 7 1 .41 87. the,exception of the Dense Wildlands the diversity of hemiptera was similar throughout the study.area. Stovep i pe Samp I er An average of 15.5 famiIies.per area were sampled using this method (see Appendix 4). As with the previous method, the greatest diversity occurred in the farmlands. There was considerable variation in standing crop between areas, with no apparent trends related to developed or undev-eloped . areas . However, the comparatively high weight.of organisms in the Dense Wi IdIands is again due to the large proportion.of molluscs in the sample. Similarly, a disportionate amount.of the yield in the Open WiId-lands was attributable to 7 odonata nymphs.- The Dense Wildlands and Public Shooting Marsh had comparatively few diptera, hemiptera or coleoptera. The Sturgeon Slough Marsh showed a paucity of coleoptera but was relatively well represented by hemiptera and diptera. Thus the 1972 invertebrate samplings served as a pilot study and provided a perspective on the relative diversity and yield of aquatic organisms between habitats in the study area. (2) .1973 Samp I ing Two main objectives were sought in 1973. The first was to establish an inventory of invertebrate diversity and yield in important habitats within the study.area. Such an inventory would provide the dual purpose of (a) providing a foundation on which further aquatic invertebrate research in the study area might be based and (b) indieate, through family "richness" and total standing crop, the relative suitability of certain habitats to support low trophic level primary consumers. The second objective was to establish the density and standing crop of invertebrate families considered potentially important to young waterfowl within the habitat known to support maximum brood use, as . the brood surveys. This would provide a "standard" against.which the density and yield.of -these' same families in areas of lower brood production could be compared. In this manner some indication as to the role of food in limiting brood.production might be gained. The' sampling was conducted, in three habitat types, namely, Ag. I, (the area of relatively high brood production), Ag. II and the Sturgeon. Slough Marsh. The number of samples taken per habitat were 50, 28 and 75 respectively. A total of 968 individuals representing 39 families were collected in Ag. I (see Appendix 5). Totals for Ag. II were 455 individuals in 35 families whereas the marsh totals were 637 organisms in 86 families. Of the 39 families present in Ag. I, 23 occurred as less than I. per cent of the population. Similarly, 18 of 35 families occurred as less than I per cent of the population in Ag. II whereas 24 of 36 families fell into the same category in the marsh. Based on the yield of the samples the habitat supporting most ducklings, Ag. I, produces a standing crop of 1.90 lbs/ surface-acre of invertebrates. Comparatively, Ag. II supports 5.09 lbs/ surface-acre whereas the invertebrate standing crop in the marsh was calcu lated .to be I..28 ' I bs/surface-acre. .-To delineate the invertebrate families potentially ducklings, it was necessary to consider food habit studies conducted else-where (Chura, I 961;' Perret, 1962; Sugden, 1973). These worker's have shown that certain invertebrate orders and, in particular, certain families with those orders, contribute substantially to the duckling food base wherever they occur. Thus, the selection of 12 invertebrate families occurring in the study area as potentially important to ducklings is predicated upon the importance elsewhere. 89. . , Numbers of organisms per unit area of these 12 invertebrate families, for each of the three habitats,.are shown in Fig. V-l. Keeping in mind the designation of-Ag. I as the basis of comparison, two conclusions become apparent: I) with the,exception of 3 families, Ag. II supports as many, or more, invertebrates potentially important to waterfowl as does Ag. I and 2).with the exception of chironomidae, coenagrionidae and lymnaeidae,, the marsh environment is less .productive of total numbers of. potential duckl ing foods than is Ag. I. Another approach to the relative proportions of a given invertebrate family among the 3 habitats is contained in Fig. V-2. This indicates further the re I at'ionsh'ip" between Ag's I and 1 I noted in (I) above. In addition, the absence, or negligible presence, in the marsh of 5 families commonly occurring in Ag. I is clearly shown. Only one family, the chyrsomelidae, was common in the marsh and rare in the agricultural areas. Similarly, only one family, the notonectidae, were present in Ag. I and not in Ag. II. Comparison of the standing crops of the 12 families (see Fig. V-lb) shows a similar distribution among the habitats as was found with numbers-of organisms. Though not applicable in all families it would appear that there is a trend for we ight-per-organ i sm to be greater in Ag.'- II than was found in Ag. I. Further evidence of this is demonstrated by considering the relative distribution of standing crop of a given family among the 3 habitats, (Figs. V-2 and 3). This, in part, accounts for the difference in total stand-ing crops calculated for each habitat. These showed that Ag. II, with'3.54 Ibs/surface-acre supported more than twice the yield found in Ag. I (1.35 Ibs/surface-acre) and more than three times that found in the marsh (1.15 lbs/ surface-acre). The distribution of this yield, according to order is shown in Figs. V-4, 5 and 6). .90. U J FIGURE V-1:-RELATIVE NUMBERS AND YIELDS OF 12 IMPORTANT INVERTEBRATE FAMILIES IN THREE HABITATS-1973 91 FIGURE V - 2 : - RELATIVE P R O P O R T I O N S OF T W E L V E I N V E R T E B R A T E F A M I L I E S AMONG T H R E E S E L E C T E D HABITATS-1973 75A 5 H 25H C H I R O N O M I D A E T I P L ) LI D A E C O R I X I D A E N O T O N E C T I D A E UJ O z HI cc ZD o o o 75 5 J, 25' G E R R I D A E H Y D R O P H I L I D A E D Y T I S C I D A E C H R Y S O M E L I D A E 75' 5 H 2 5 H I » I C O E N A G R I O N I E J A E L Y M N A E I D A E Ag-I A g-ll P L A N O R B I D A E Marsh P H Y S I D A E .92. FIGURE V - 3 : - DISTRIBUTION OF YIELD OF 12 INVERTEBRATE FAMILIES AMONG THREE S E L E C T E D HABITATS-1973 LU o z UJ cc cc 3 o o o 1001 75' 50 25' OJ 100" 75-'SO 25 C H I R O N O M I D A E i * o i rrn°» G E R R I D A E iocr 75* 50* 25 oJ T I P U L I D A E H Y D R O P H I L I D A E l l l l :;i-''.i''>,''7 \ •' C O R I X I D A E D Y T I S C I D A E C O E N A G R I O N I D A E L Y M N A E I D A E P L A N O R B I D A E II N O T O N E C T I D A E C H R Y S O M E L I D A E n P H Y S I D A E Marsh FIGURE V - 4 - - D I S T R I B U T I 0 N OF Y IELD OF POTENTIALLY IMPORTANT IN VE RT E B R A T E S -Ag-l l ,1973 FIGURE V - 5 : - DISTRIBUTION OF Y I E L D OF POTENTIALLY IMPORTANT INVERT EB R A T E S - A g - l l , 1 9 7 3 FIGURE V-6-.-DISTRIBUTION OF YIELD OF POTENTIALLY IMPORTANT INVERTEBRATES - STURGEON SL. MARSH, 1973 96. 5.3.0 D i s c u s s i o n ' . . . . ' ' . .5.3.1 D e n s i t y and Y i e l d of I n v e r t e b r a t e s i n V a r i o u s H a b i t a t Types, and t h i e r Re I a t i o n s h i p t o Brood D i s t r i b u t i o n (a) S i g n i f i c a n c e of I n v e r t e b r a t e s t o Young Waterfowl The i m p o r t a n c e of i n v e r t e b r a t e s as a h i g h p r o t e i n s o u r c e f o r duck-I i ng s has been w e l l documented i n t h e l i t e r a t u r e ( Moyle, 1961; C h u r a , 1961; P e r r e t , 1962; Sugden, 1973). Hence i t was f e l t t h a t an i n v e s t i g a t i o n o f t h e w a t e r f o w l p r o d u c t i v i t y i n an a r e a would' be i n c o m p l e t e w i t h o u t some e x p r e s s i o n o f t h a t a r e a ' s a b i l i t y t o p r o v i d e t h i s a p p a r e n t r e q u i r e m e n t . However, t h e n a t u r e of t h e s t u d y a r e a , and t h e s t u d y i t s e l f , n e c e s s i t a t e d c o n s i d e r a b l e m o d i f i c a t i o n o f t h e standard' t e c h n i q u e s . e m p I o y e d e l s e w h e r e . For example, c o l l e c t i o n of v a r i o u s aged d u c k l i n g s f o r a n a l y s i s , of g u l l e t c o n t e n t s would have s e v e r e l y p r e j u d i c e d o t h e r segments of t h e s t u d y i n c l u d -ing p a i r c o u n t s , brood c o u n t s and banding s u c c e s s . I t was a l s o u n l i k e l y t h a t one c o u l d c o l l e c t a s a m p l e . s i z e l a r g e enough t o be s t a t i s t i c a l l y a c c e p t -a b l e w i t h o u t s e r i o u s l y r e d u c i n g t h e l o c a l duck p o p u l a t i o n (Sugden, 1973). A ' f i n a I ' c o n s i d e r a t i o n was t h e p o s s i b i l i t y of u n f a v o u r a b l e p u b l i c r e a c t i o n t o such t e c h n i q u e s and t h e ' d e s i r e t o m a i n t a i n good r e l a t i o n s w i t h both c o n -s u m p t i v e and non-consumptive u s e r s of t h e a r e a . As i n d i c a t e d e a r l i e r , t h e approach f i n a I Iy s e I e c t e d was t o e s t a b l i s h t h e d i v e r s i t y , d e n s i t y and y i e l d of i n v e r t e b r a t e s i n h a b i t a t s , of known brood p r o d u c t i o n . T h i s was done on t h e a s s u m p t i o n t h a t t h e hab.itat s u p p o r t i n g t h e most broods' must, in t h e p r o c e s s , be p r o v i d i n g an adequate. food supply.. The i n v e r t e b r a t e i n v e n t o r y of t h a t " s t a n d a r d " h a b i t a t was t h e n used t o e v a l u a t e 9 7 . t h e d u c k l i n g f o o d p o t e n t i a l o f t h e o t h e r h a b i t a t s . T h u s , a h a b i t a t w h i c h c o n t a i n e d a s i m i l a r , , o r g r e a t e r , i n v e r t e b r a t e d e n s i t y . and b i o m a s s , b u t s u p p o r t e d f e w e r b r o o d s t h a n t h e " s t a n d a r d " h a b i t a t , c o u l d be a d j u d g e d t o be p r o b a b l y a f f e c t e d by some f a c t o r o t h e r t h a n f o o d . P r i o r t o f u r t h e r d i s -c u s s i o n i t i s n e c e s s a r y t o c o n s i d e r t h e s i g n i f i c a n c e o f d i v e r s i t y , n u m b e r s and y i e l d i n i n v e r t e b r a t e p o p u l a t i o n s i n r e l a t i o n , t o t h e i r u t i l i z a t i o n by w a t e r f o w I . B o t h p r e f e r e n c e a n d a v a i l a b i l i t y i n f l u e n c e t h e c h o i c e o f f o o d e x e r -c i s e d by d u c k s ( S u g d e n , 1 9 7 3 ) . A v a i l a b i l i t y , however,.- i s n o t n e c e s s a r i l y s y n o n o m o u s w i t h a b u n d a n c e . An o r g a n i s m can. be h i g h l y , a b u n d a n t b u t h a v e I i m i t e d a c c e s s i b i I i t y . C o n s p i c u o u s . n e s s o f a f o o d i t e m i s i m p o r t a n t i n d e t -e r m i n i n g i t s a c c e s s i b i l i t y a n d c a n be m o d i f i e d by s i z e , c o l o u r a t i o n , t r a n s -p a r e n c y , c a m o u f l a g e , movement o r a n y c o m b i n a t i o n o f t h e s e f a c t o r s ( C h u r a , 1 9 6 1 ) . D i v e r s i t y o f o r g a n i s m s a v a i l a b l e t o d u c k l i n g s may be i m p o r t a n t i n e n a b l i n g t h e b i r d s t o m a i n t a i n n u t r i t i o n a l l y b a l a n c e d d i e t s . Of t h e 13 . f o o d s he t e s t e d , S u g d e n ( 1 9 7 3 ) f o u n d t h a t o n l y c h i r o n o m i d l a r v a e , c o r i x i d s , a n d g a m m a r i d s p r o v i d e d a c o m p r e h e n s i v e r a n g e o f a m i n o a c i d s . B i o m a s s , i t s e l f , ' i s , i m p o r t a n t f r o m s e v e r a l s t a n d p o i n t s . Many o r g a n i s m s o f a v e r y s m a l l s i z e c o u l d r e q u i r e a l a r g e e n e r g y e x p e n d i t u r e f o r t h e d u c k l i n g t o meet i t s e n e r g y r e q u i r e m e n t s . S i m i l a r l y , a v e r y few. o r g a n i s m s o f a l a r g e i n d i v i d u a l b i o m a s s c o u l d a l s o r e s u l t i n an i n e f f i c i e n t e n e r g y e x p e n d i t u r e f o r t h e r e t u r n s g a i n e d . ( b ) . R e l a t i v e I m p o r t a n c e o f I n v e r t e b r a t e F a m i l i e s t o W a t e r f o w l C h u r a ( 1 9 6 1 ) f o u n d t h a t d e s p i t e t h e many v a r i e t i e s o f i n v e r t e b r a t e s p r e s e n t i n h i s s t u d y a r e a , f e w w e r e h i g h l y a b u n d a n t , ( o r o f i m p o r t a n c e t o m a l l a r d d u c k l i n g s ) . F o r i n s t a n c e , 17 o f 25 f a m i l i e s i n h i s m a r s h s a m p l e s , o c c u r r e d a s l e s s t h a n I p e r c e n t o f t h a t p o p u l a t i o n . A l s o , o f 45 d i f f e r e n t food items consumed, 32 constituted less than I per cent of the diet. Similar results in population distribution were found in this study where 27 of 44 families in the agricultural areas and 24 of 36 families in the. marsh occurred as less than I per cent of the respective populations. However, despite regional differences in location, many food habit studies of juveniIe waterfowl have consistently shown the importance of certain families of invertebrates to ducklings. The occurrence of chirono-mid larvae and Odonatan nymphs, in the diets of downy widgeon (Mareca ameri- cana.) from central British Columbia was noted by Munro (1949). Larval, pupal and aduIt forms of tendipedid, gastropods, nymphal forms of ephemerop- . tera and odonata, and corixids were among the more important food items of juvenile and adult canvasbacks (Aythya val isineria), redheads (Aythya amer- icana.) and scaup (Aythya affinis) in southwestern Manitoba (Bartonek and Hickey, 1969). Juvenile mallards (Anas p I atyr.hynchos) near Great Slave Lake contained significant proportions of larval predaceous diving beetles, notonectidae, adult leaf beetles (chrysomeIidae) and damselflies (coenag-rionidae) in their esophagi, (Bartonek, 1972). Besides noting.the importance of chironomid larvae in the diets of most, if not a l l , young ducks, Sugden emphasized the high nutritional value of'this family. He a iso suggested that corixids would have simiIar importance in those areas in which they are avail-able. Based on these f i nd i ngs, 1.2- families (see Table V-2) present in the Pitt area were selected as potentially important sources of duckling food. Their relative abundance and yield is discussed in terms of those occurring i n Ag . I . Chironomidae: Similar numbers•of both larval and adult forms of this occurred in each of the three habitats. The slightly greater biomass in.Ag. II is attributable to the larger number of larvae found in this area. Though usually associated with the substrate, the presence of these slow-moving larvae in samples taken at the surface infers a' simi Iar avaiIabiI ity to duck I i ncs.• . T i puI I dae: The inclusion of tipulidae as a potential source of duckling food is based more on local conditions than the . findings' of other researchers. First noted in the Vancouver area in 1965, these dipterans were causing considerable damage to large dairy farms near Pitt Meadows by 1967 (Wilkinson and MacCarthy, 1967), The extensive acreages of pasture (see Table I I 1-2) in both agricultural areas provides ideal habitat conditions for the marsh crane fly. Casual investigation of pastures in Ag. I during the spring of. 1972 revealed large numbers of larvae present in the sod. Larval forms are available until early June at which.point . pupation occurs. Hence, the relatively mobile larval forms would be available to the bulk of the duckling. broods hatched in this area. The relatively low number of crane fly in the marsh is attributed to the lack of preferred habitat. Corixidae: Corixids .pI ay an important role in aquatic communities as primary converters of low-protein plant food to animal protein (Usinger, 1963). They satisfy the requirements of both conspicuousness and availability by virtue of their mobility and necessity to rise to the'; surface 'to replenish their oxygen supply. Hence, the importance, in the diet of ducklings, attributed to this hemipteran by previous investigation (Sugden, 1973). The majority of corixids found in the agricuIturaI areas were nymphal forms, which explains the relatively low yield encountered. Comparatively, Ag. II appears to support over 30% more organisms per sur-face acre than Ag. I. However, 66% of the total sampled in Ag. II were encountered in one net sweep. A far more gen-era I distribution of corixids was evident in Ag. I. Compared to the latter area, corixids were virtually absent from the marsh. However, as evidenced by the biomass per organism, most specimens from the marsh area were adjudged to be the adult form. This may be interpreted in several ways. Krull (1970) attributed weekly variability in both numbers and we.ight, in part, to natural flucutations in the life cycle of inverte-brates. In the same vein, Moyle (1961) a I Iuded to the occur-rence of several life cycles per season for invertebrates when he referred to tota! annuaI' production of invertebrates being several times the standing crop. Thus, the presence of primarily adult forms may indicate only a temporary low point in seasonal abundance. Similarly, differences in edaph hydric, and floristic features between the agricultural areas 101. and the marsh (see Section 4.0.0) may account for temporal disparity in the synchronization of life cycles of a given .invertebrate species within the study area. Further study would- be necessary to determine if low corixid numbers in the. marsh were "real" or "temporary". Confirmation of the former could lead to consideration of this as a contributing factor when comparing differences in waterfowl productivity between areas. 4. Notonectidae: Due to their low abundance, they are probably the. least important of the major families under consideration. Though similar to corixids in their need to surface for oxygen, they are rapid swimmers and probably difficult to capture when they do surface (Sugden, 1.973). 5. Gerridae: I included gerridae as one of the potentially impor-tant duckling foods because df its conspicuousness and apparent availability in most of the aquatic environments within area. Although, some adult forms were, present various larval instar forms predominated, espec-ially in Ag.. I where this family accounted for a dispor-tionately low biomass per surface-acre compared to Ag. II and the marsh. Considering the widespread distribution of this hemipteran (Pennak, 1953),it occurs with surprising infrequency in duckling food habit studies. There was no suggestion in the literature as to whether this reflected availability or preference by the birds. .Degree of utiliza-102. tion in the study area can only be estabIished via collection of various aged ducklings and. subsequent examination of their guI Iet.contents, 6. Hydroph i I i dae: The reason for the absence of the coleopteran, hydrd-philidae, from the marsh area is not known. .PrimariIy herbi-vorous, (Leech and Chandler, 1963) these beetles are commonly found in quiet shallow waters, particularly where there Is considerable vegetation present. Thus, it would appear that the more obvious habitat requirements are not. the . ... marsh. Although the number of organisms per surface-acre are similar in the two agricultural areas, there is a consid-erable, greater yield in Ag. I I. This probably reflects the greater number of adult beetles present in.this area. Leech and Chandler (1963) noted that this beetle and its larvae are an. important source of food for ducks. Hence, its absence from the marsh may be worthy of consideration when comparing duck production in that area and Ag. I. 7. Dyt i sc i dae: Dysticids are exclusively aquatic beetles'to which the presence of a clean substrate and aquatic vegetation seem to be almost indispensable (Pennak, 1953). Their absence from muddy bottoms may account, in part, for the relatively low numbers encountered in the marsh area. In this latter area s i l t , probably originating, from backflow of the Fraser River in pre-dyking days and supplemented since then by.periodic floods and seasonal run off from local mountains, has settled 103. out through much of this area. Conversely, periodic cleaning of ditches and a fairly constant waterflow due to the operation of drainage pumps results in firmer bottoms of a glel texture being present in much of the agricultural areas. 8. Chrysome l.i dae: The virtual absence of chrysomeIidae from the agri-cultural areas and its relative abundance in the marsh is largely attributable to lack of suitable habitat in. the former areas. Commonly called the Leaf Beetle, this colipteran is considered to be-quite specific in its choice of aquatic vegetation as a food source. Among the preferred plants listed by Leech and Chandler (.1963) are Nuphar, Nymphaea, MyriophyI I urn, Sagittaria, Sparaganium and Potomogeton. Pennak (1953) I i sts.'the. Ye I low Pond Lily (Nymphaea polysepalum) of the, principa I foods. Sim-ilar preference by Chrysome I i dae in the study area was noted.. The leaves of the Yellow Water Lily ; in the.marsh area often abounded with Leaf Beetles and counts of 12 - 15 beetles per leaf were not uncommon.. Conversely, the relative absence of Water Lily in the waterways of the agricultural areas precludes a similar abundance of this beetle in those areas. It should be noted that the relatively clumped distribution of Yellow Water Lily in the marsh area resulted in a compara-tively few samples being randomly, located in them. Hence, the sampling scheme in the marsh may have resulted in an . 104. underestimation of the importance of this beetle as a potential source of duckling food in that area. 9. Coenagrionidae: The numbers of this odanatan present in Ag. I and the marsh are very similar, as was the yield per surface area. Surprisingly, the yield obtained in Ag. II was lower than that found in Ag. I although more than .twice • the number of organisms were present in the former. This was a reversal of the usual trend in which weight per individual was generally largest in the Ag. II area. I suspect that the conspicousness, availability, size and numbers of the damselfly naiads present in all three areas may make this organism one of the more important sources of duckling food in the study area. The inclusion of gastropods as a potentially important source of duck-ling food is subject to some contradiction in the literature. Snails have a lower protein content and a higher ash content than many other aquatic invertebrates (Moyle, 1961; Sugden, 1973). This may account, in part, for the variable utilization by ducklings encountered by other investigators (Bartonek and Hickey, 1969; Bartonek, 1972; Sugden, 1973). The conclusions by Sugden that certain species of waterfowl select gastropods whereas others ignore them further complicates a qualitative evaluation of their importance. Their substantial contribution, in terms of both numbers and yield,, to the invertebrate fauna of the study area, however, necessitates some considera-tion be given to their local distribution. 105. 10. Lymnaeidae, Planorbidae and Physidae: Lymnaeidae occurs frequently in the marsh.area but in relatively small numbers in the agricultural areas. Con-versely, planorbidae and physidae are virtuaI Iy absent from the marsh but present in large numbers and biomass in the agricultural areas. Examination of certain ecological fac-tors known to influence distribution, numbers and'size of various species of gastropods may offer a partial explanation of these parameters as measured on the study area. Generally speaking, soft waters (pH >7.0) contain, few gastropod species and individuals whereas hard waters (pH < 7.0) often support a considerable density and diversity of these organisms. SeveraI.chemical characteristics of a waterbody are known to affect the aforementioned distribution. Among these is the amount of dissolved salts present. In particular, certain minimal levels of calcium carbonate are essential for construction and maintenance of mollusca shells. A considerable variation in carbonate content between the waters of the agricultural areas and the marsh was demonstrated earlier in this study (see Sec. 4.2.3). To what extent this is reflected in the low densities of lymnaeidae in the agri-cultural habitats relative to the marsh is unknown. Some species of lymnaeidae apparently thrive in low carbonate waters and this may account for the relative abundance of that family in the marsh habitat. However, such a correlation awaits further study. Physical factors also influence snail distribution. 106. Although a few groups, such as.lymnaea, are present through a-wide range of habitats many other groups are far more specific •in their requirements. Hence, substrate and water depth are two more possible explanations for variations in snail distri-bution between habitats. Finally, biotic factors such as vegetation density and availability of food are . important in gastropod distribut ion. For example, physidae'seem to prefer habitats in which aquatic vegetation and organic debris occur, in moderate amounts and seldom is found in dense stands of vegetation (Pennak, 1953). In conclusion, it has been shown elsewhere in this study that the habitats in question vary widely in land use and management input. Thus, leaching of fertiI izers and animal wastes, ditch cleaning and relatively stable water levels have resulted in noticeable differences in the water quality of the three habitats. I suspect further study would confirm this as the factor most affecting variations in the density and yields of gastropod families in the study area. As mentioned previously, definite conclusions on i nvej~tebrate'ava i la-bility'and duckling utilization in respective habitat types must await further investigation. However, a comparison, between habitats, of the density and standing crop of twelve invertebrate families selected as poten-tially valuable to ducklings permits several observations: (I) with one or two minor exceptions, the density and yield of twelve selected inverte-brate genera in Ag. II equals or exceeds that determined for the same genera in Ag. I. Having previously assumed that current brood production in Ag. I indicates an adequate food resource exists in that habitat, it follows that 107. the . cons i d.erab I y lower waterfowl production encountered in Ag. II probably results from some other environmental factor or factors than food and (2) as only.five of the twelve selected invertebrate fami Iies are present in the marsh in numbers and yield.equal to, or greater than, those found in Ag. I., food may be a contributing factor to the low waterfowl productivity in the marsh. In addition to these postuI at ions, this section of the study has es-tablished the food base at which present maximum waterfowl production in the study area occurs. This, in turn, permits gross evaluation of other habitat types with respect to their capability to sustain ducklings during the c r i t i -cal early growth stage. (c) Other Factors Affecting Invertebrate Distribution and Availability Ducklings, due to unspecia Iized feeding apparatus and behaviour, feed principally on invertebrates at or close to the surface during the first few. days of life (Chura, 1961). The same author also estabI ished that density of flying invertebrates is.maximum at, or just above, the surface of open water or mud. Similarly, the density in emergents is maximum at a level . corresponding with the top portion of the vegetation. The number of inver-tebrates decreased progressively below this level to the water surface. The vegetation cover map (Appendix I), indicates that stands of tall emergents such as hardstem bulrush and smaI I-fruited bulrush change abruptly to terrestiral species such as bluejoint and hardhack throughout much of the marsh and its associated wildlands. Thus, large expanses of this habitat are vegetated in a manner than minimizes the availability of the. predominant • food source. A similar situation could exist in the Public Shooting Marsh which is predominately vegetated by dense stands of _S. acutus except at the northern edge of the marsh. 108. The correlation between invertebrate density and amount of aquatic vegetation present has been well documented in earlier studies'(Moyle, 1961; Krull, 1970). Detailed analysis of species diversity of aquatic vegetation in.the various habitat types was beyond the scope of this study. However, yield determinations of submerged aquatics in Ag. I and Sturgeon Slough Marsh did reveal a 20% greater yield per surface acre in the former area (see Section;4.2.2). Generally speaking, Watershield, Yellow Pond Lily and Potomogeton species rarely occurred in numbers in the agricultural areas. Conversely, no duckweed (Lemna spp.) was.found in the marsh area though common in the ditches of the farmlands. Absence of Leaf Beetles from the. agr icu l.tura I areas was earlier attributed to the lack of suitable habitat in the form of Lily Pads. A more detailed study of invertebrate - aquatic plant relationships in the study area could account for further disparities in invertebrate abun-dance and distribution observed between habitat types. A final observation on the invertebrate population differences between habitat types concerns the distribution of carp (Cypri nus carp io). Though in evidence throughout the study area it appears most abundant in the.marsh.areas. Travel through the marsh in late spring and early summer is accompanied by the constant swirling of startled fish nearby. The impact of these animals on the invertebrate-fauna is unknown. However, examination of carp stomachs from Pymatuning Lake, Pennsylvania revealed contents of approximately 65% animal .matter (Tryon, Jr.., 1954). In Minnesota, carp are thought to be com-petitors with puddle ducks for chironomid larvae in shallow water (Moyle, 1961). In Okanagan .Lakes, food of the carp included larvae and nymphs of aquatic insects and small snails (Carl et al., 1967). Assumption of similar feeding habits in the study area introduces yet another factor to be considered when discussing invertebrate - waterfowl productivity interactions in the various habitat types.- - ' IQ9. 6.0.0 WATERFOWL CENSUS METHODS 6.1.0 Materials and Methods 6.1.1 Pairs Five counts of breeding pairs in the six habitat types were con- . ducted in 1973. The first count occurred during the period February 23 -24. The next was conducted on March 30 - 31 and successive counts occurred in 2 week intervals thereafter, that is, April 12 - 15, April 26 - 28, and May 10 - 13. All ducks sighted were classified into one of four categ- • ories, namely, single pair, lone males, lone females, or.flocked birds (Hailaday, 1971), In response to the widely divergent habitat types (see Section 3.1.0) it was necessary to conduct two types of pair counts. The first type could be termed a "complete" count and was utilized in the Ag. I, Ag. II, Open Wildlands and Dense Wildlands habitat types. Each of three observers were supplied with a xeroxed 9 inch x 9, inch air photo (I inch = 1000 feet) on which his respective survey route was marked (Appendix 6). Close adherence to his marked route by each observer resulted in a series of rendezvous by 2 or more of the observers during the survey of a given habitat type. These rendezvous served to minimize roll-up during the pair count and as an effective check on duplication and/or ommission during brood counts. During the survey each observer would use 8 x 35 binoculars to identify observed ducks and would then plot their location on the air photo. Using, this method the total shoreline of all ditches, borrow pits, rivers and waterbodies was censused within the applicable habitat type, hence.the name "complete" survey. This is in contrast to the survey method utilized in the two marsh habitat types. By the nature of their size and vegetational cover, these I 10. preclude any type of "complete" coverage as outlined above. Therefore, a. "comparative" survey, in which a similar route within each habitat type was surveyed, was instituted. A single observer with 8 x 35 binoculars and uti I i -zing an 8 foot punt would row or paddle along the survey route and mark on the xeroxed air photo all birds observed-sitting-or fIushing-along the route. . 6.1 .2 Nests The chronology of waterfowl nesting in the study area in 1972 and 1973 was primarily derived by back-dating broods that had been aged according to various plumage 'characteristics (GoI lop and Marshall, 1954). From these data nest initiation was calculated and hatching curves derived. These data were supplemented to some extent in 1973 by conducting extensive nest searches for mallard, cinnamon (Anas cyanoptera) and blue-winged (Anas discors) teal nests in segments of the study area. Two methods were used to search for nests. The.first was a by-product of a regular springtime farming practice involving the use of a"tractor-mounted cutting bar to cut back ditchbank grasses and shrubs. The.blade is positioned approximately 12 inches off. the ground and can act as a flushing bar without directly destroying the nest. Farmers were offered a reward of $4.00 per nest for each nest discovered in this manner and subsequently reported. The second method involved walking along ditchbanks and road allowances, manually beating out the surrounding vegetation in an attempt to flush incubating hens. To minimize the possibility of injuring the nest, but to maximize the noise fac-tor, bamboo grass rakes were used as beating devices. A third,, more indirect, method involved searching freshly burnt dykes and fields for.evidence of current or former nesting activity. '. Several other methods of, locating nests were considered. Due to the dense stands of hardhack and b I ackberry. v i nes, the dragging of a hand-held rope (Earl, 1950) was deemed impractical in many areas. Those areas where such a method could, be'aplied, that is, hay fields, were usually too far advanced in growth for the farmer to permit such a method to. be used. Due to the relatively low number of breeding waterfowl in the study area, obser-vations of hens returning to their nests (Earl, 1950; Keith, 1961) was con-sidered too time consuming. In, both 1972 and 1973 considerable data on the nesting chronology of wood duck (Aix sponsa) were obtained by frequent checks of the artificial nesting boxes utilized by this species. In 1972, in excess of 100 of these boxes were placed in trees throughout the study area by personnel operating under the auspices of an L.I.P. grant. The majority of these boxes were checked throughout the nesting season and the results, of each visit recorded on a file card (Robinson, 1972 - unpublished data). In 1973, the writer continued to check eight of the original boxes and supplemented this total with 28 additional boxes. Of these, 22 were placed on 2 inch diameter metal poles approximately 10 feet long, and the balance were placed approximately 15 feet above ground level in.nearby trees. These were checked on a weekly basis, when possible, and the status of each box at that time was documented on 3 inch x 5 inch file cards. 6.1.3 Broods Two brood counts were conducted in 1972 and 1973 respectively. In 1972,. these covered the periods May 24 - 27 and June 18 - 22. In 1973, the counts were conducted during the period May 25 - 26 and June 23 - 24. The actual method of census in the various habitats was identical to that previously des-cribed for the breeding pair counts (see Section 6.1.1). AM broods sighted I 1 2 . were identified to'species and aged according to the method of Gollop and Marshall ( 1 9 5 4 ) except in the case of wood duck. These were aged based on. data collected on captive birds held within the study area (Appendix 7).. The number of ducklings per brood were counted and, in those broods . considered complete, this was used in' caleu I ating duckling mortality. In addition, the .location and numerical status of all adult ducks seen during' the brood counts were recorded. 6, I . 4 Predation All potential predators observed during field work in 1972 and 1973 were documented as to species, activity and location. Cases of observed predation were similarly noted. All instances of predation involving water-fowl, pheasants, and grouse were closely examined to determine the species and age of.the prey and to provide tentative identification of the possible, predator, that is, avian or mammalian. A small number of Otter (Lutra cana- densis) and Black Bear (Ursus americ'anus) scats were examined for evidence of feeding on waterfowl or their eggs. 6 . 1 . 5 Movements of Local Waterfowl To measure this parameter required the capture of brood hens and young and non-nesting adults moulting in the area. Manpower considerations dictated that this be carried out as essentia I Iy a one-man operation. This eliminated such trapping devices as the cannon net, night-Iighting and drive-trapping ..(Hankla and Smith, 1 9 6 3 ; Tabler and Cowan, 1 9 6 9 ) . Small., portable brood traps placed in shallow water had been used with success in Maine (Spencer, Jr., 1 9 6 3 ) . A similar device placed on a floating platform was used with consider-able success in Massachusetts (Grice and Rogers, 1 9 6 5 ) . Accordingly, three floating funnel traps were constructed for local use. These consisted of a 113. standard funnel trap approximately 4 feet x 4 feet, constructed of I inch lathing wire. The wire frame was fastened to a 1/4 inch plywood base approx-imately 4 feet x 6 feet, which dimensions provided a 2 feet apron at the fun-nel entrance of the trap. The apron serves two purposes. It provides a'n area outside of the trap on which bait can be placed leading into the trap's interior. It also serves as an attractant to waterfowl as a hauling-out site for loafing and preening activities. Several pieces of styrofoam were fast-ened to the bottom of the trap to provide flotation. The top of the trap was covered with 1/2 inch herring seine net. As captured birds would often try to fly.out of the trap upon the approach of the bander, the 'soft' roof minimized the occurrence of injury. It was found that trapped birds were less likely to escape if a baffle of netting approximately 36 inches high x 10 inches wide was placed . inside the trap approximately 13 inches from the entrance of the funnel.' This prevented trapped birds from obtaining an unobstructed view out of the trap when oppos-ite the funnel. The.'trap was baited with a 50:50 mixture of wheat and cracked corn. Captured birds were removed from the trap using a long-handled landing net. The use of a retriever to capture flightless young and moulting adults has been well documented (Gollop, 1956; Hankla and Smith, 1963). In this study a Labrador - German Shorthair cross was used, with considerable success, on both young and flightless adults. The basic technique used was to keep the dog at heel while driving the birds off the water and into adjacent heavy cover. The dog was then sent in to hunt the hiding birds and retrieve them for marking purposes. All birds captured by either method were banded with the standard U.S.F.W. aluminum band. In addition, a number of hens and young were coloured-marked 114.. using a polyvinyl nasal saddle (Sugden and Poston, 1968). Each saddle was numbered using a vinyl-based paint. To aid in field identification,' red saddles were placed on mallards, (Fig. Vl-I), yellow saddles on wood duck (Fig. VI-2) and white saddles on c i nnamon tea I. As a foI low-up to the co I our marking of the ducks, a form letter (see Appendix 8) was sent to-all state game agencies along the Pacific Flyway requesting their co-operation in reporting sightings of marked birds. 6,1.6 Hunting effort, success and species composition of the kill There are three sources from which, this data is obtainable, namely, the private hunting clubs, the hunting public, and government-operated game checks and surveys. Those clubs willing to-co-operate were provided with a Waterfowl Harvest Record Book which, in most instances, was kept in a central location in the respective clubhouses. The members were asked to enter the results of-every hunting trip on the form'provided (see Appendix 9). To randomly sample the public component of hunting activities, twenty individ-uals from the B.C. participants in the 1972-73 National Wing Survey were contacted via form letter (see Appendix 9). Those expressing a willingness to co-operate, received a personal supply of Waterfowl Harvest Record forms, a map of the area,.and the booklet "Ducks at a Distance", (see Appendix. 10). These were accompanied by a letter of instruction. On the opening day of the local duck hunting season in 1972 and 1973, a game check station was set up in the Pitt Polder area in conjunction with the provincial Fish and Wildlife Branch. Data collected included number- of hunters, area hunted, hunting success and age and species composition of the • kill (see Appendix II). As a further -source of data, all duck wings submitted by British Columbia hunters, as part of the National Wing Survey, were sorted Figure VI -2 : Immature male wood duck with attached, yellow nasa- marker. and'those containing wings. from the Pitt Valley removed for further analyses (see Appendix . I 2). This involved identifying the wing as to species and determining the age and sex by means of the wing pIumage; (Carney, 1964).. I 17. 6.2.0 Results and Observations 6.2.1 Species Composition and Distribution of Breeding Pairs In.the spring of 1972,. establishing the boundaries of the various., habitat units to be investigated within the study area pre-empted the initiation of pair counts prior to early May. As an unknown number of pairs of the various species could have terminated the pair bond at this late date it was decided to forego pair counts under such circumstances. From the five pair counts taken . in 1973 (see. Section 6.1.1), three were selected, for use in calculating the status of breeding pairs. The first (see Table Vl-I) reflects the distribution and breeding status of adult ducks present in four of the six habitat types immediately prior to the breeding season. Due to the large number of flocked ducks in the remaining two habitats, i.e. Sturgeon Slough and Public Shooting marshes at this time it was not . possible to obtain an accurate breakdown as to sex. However, observation of.over 500 ducks, including mallard, green-winged teal (Anas caroIi nens i s) widgeon, and gadwaI I (Anas strepera) on Feb. 28, indicates a considerable pre-nuptiaI waterfowl presence in these habitats also. The second and third counts cover the period of peak nest initiation (see Section 6.2.2) for two of the.three main species of breeding waterfowl in the study area in 1973. For blue-winged and cinnamon teal, nest initiation, in 1973 was assumed to be the same as occurred in 1972 (see Fig. VI-4). From the number of single males, single females, pairs and flocked birds censused during each of. these two counts (see Table VI-2), an estimate of the number of breeding pairs can be made (see Table VI-3). These are obtained by assuming that the maximum number of actual breeding pairs of a species, are most likely observed during the peak of nest initiation for that species. Table V 1 — 1 = Spec i es Selectee Composition and .Distribution of Habitat Areas — Pitt Valley,. Adult Puddle rebruary 23 -Ducks in 24, 1973 Species Ag. West 1 East Ag. 1.1 Open WIdld. Dense WIdld. Total No. Bi rds i n Tota1 not Sexed Total Birds Sexed No. Pa i red Birds Pa i red Ma 1 lard . 68 16 69 20 6 179 36 \ 143 140 98.0 W i dgeon • 4 , ' - . 28 9 - .41 15 26 24 92.5 Gadwa 1 1 - - • - - - - ' - -Wood-Duck - - — - - . - - -G.W. Teal 58 12 87 7 - 164 1 14 50 42 84.0 B.W. Teal - - - - - • -' • - -Cinnamon Teal - • - - - - -119. table VI-2: Sequential Observations of Breeding Pairs in Various Habitats - Pitt Valley, 1973 secies Ag. 1 West East Ag. II Open Wi 1 dlands Dense Wild lands Sturgeon S lough Marsh Public Shooti ng Marsh a 1 1 a rd .W./Cin.Tea 1 3od Duck .W. Teal 4/12 4/27 4/12 4/27 4/12 4/27 4/12 4/27 4/12 4/27 4/12 4/27 4/12 4/27 10 II 7 1 7 12 2 6 8 9 2 4 5 4 5 1 1 10 9 5 . 3 2 3 4 - . 1 1 1 1. 1 1 3 1 Table VI-3: Number of Breeding Pairs Observed in Various Habitats during Peak of. Nest Initiation for Respective Species - Pitt Valley, 1973 Spec i es Ag. West 1 Ag. 11 _ • a Open East Wild lands Sturgeon Dense Slough Wi Id lands Marsh Publ ic Shooti ng Marsh Ma 1 lard 10 7 5 10 2 . 3 1 B.W./Cin. Teal 12 •6 . 5 1 3 Wood Duck 9 4 1 5 - 1 1 G.W. Teal • - - - - 1 -120. 6.2.2 General Nest Data in an attempt to document cover preference, clutch size, hatching success, etc. of ground-nesting'waterfowl, a total of 24.2 miles.of ditch-bank, dyke and roadside was checked for nests (see Section 6.1.2). In addition, 3.1 miles of burnt ditchbank and 10.0 acres of burnt pasture and wildlands were surveyed, as were 5.0 acres of hayfield after mowing operations. Nests were also located incidental to other field operations and, on occasion, were reported by farmers. These combined efforts resulted in a total of nine active nests being found during the two field seasons (Table VI-4). In addition, two mallard nests and one teal nest from a previous year were loca-ted in burned areas. (a) Mallard Nesting Data The calculated length of the mallard nesting season in 1972 was 113 days (March 4 to June 24). By back-dating from the calculated age of four-teen different broods, the nest' :\ n i t i at i on peak was found to be between April 14 and May 5. Similar calculations revealed that'the peak hatch occurred between May.20 and June 10 (Fig. Vl-3). In 1973, the mallard nesting season spanned 117 days (March 20 to July 14). The peak of nest initiation occurred week ending April 7, whereas the peak hatch took place during the week ending May • 12 (Fig. Vl-3) . Three of the four mallard nests found on ditchbanks were located in mixed stands of blackberry bushes and reed canary grass. In each instance, the dead growth of grass was interwoven and supported by the vines of the Rubus thereby forming a canopy of teepee configuration. Another ditchbank mallard nest was located in a pure stand of reed canary grass (Fig. VI-6). The dead, growth had lodged and the nest was located under this canopy. The 121 . Table VI -4: Nests Found in Pitt and Alouette Polders - 1972 and 1973 Date Species No. Eggs Habitat • Type Cover Type Disposition 3-25-72 Ma 1 lard 13 Ag. 1 West Ditchbank (black-berry - R.C. grass) 100$ hatch 5-27-72 Cinnamon T. 8 Ag. 1 West Fa 11ow f i e1d (grass spp.) 100$ hatch 5-23-72 Ma 1 lard. 10 Open Wldld. Ditchbank (black-berry - R.C. grass) 100$ hatch 4-1.1-73 Ma Hard 10 .Ag. 1 West Ditchbank (R.C.grass) 100$ hatch 4-1 1-73 Mallard 3 Ag. 1 West Ditchbank (wi11ow, blackberry) deserted, hen hit by cutting bar 4-29-73 Mallard 10 Mountainview Hardhack- bluejoint destroyed, by unknown Club ecotone predator. Nest had previously been burnt but femaIe had returned. 5-25-•7.3 Cinnamon T. 8 Roadside 3 ft. back from destroyed by ditch, ditch in R.C. mowi ng Ag. 11 • grass - 18" high 5- 30-•73 C i nnamon T. 1 1 Roadside -1 ft. from ditch- destroyed by d itch, bank lip in R.C. mow i ng Ag. 1 grass 36" high 6--22--73 Green-winged 6 Open Wldld. Ditch bank 100$ hatch teal 122. .FIGURE VI -3 : -MALLARD HATCHING CURVES FOR PITT AND ALOUETTE POLDERS-1972 &1973 Q O O cc co d z 5 4 H 19 72 19 73 i ^ 0 J | | - | 1 :—i T—: 1— 8 I 6 APR IL MAY 7 I 5 WEEKS-ENDING i——r 3 i r JUNE 19 72 19 73 FIGURE VI-4:-BLUE-WINGED AND CINNAMON TEAL HATCHING CURVES FOR PITT & ALOUETTE POLDERS-1972 5- i (fi Q O O CC CO d z 4H 3^ 24 MAY - i r J U N E T~ r— 1— 1 j 1 JULY 1972 WEEKS-ENDING 123. Figure VI-6: Mallard nest located in dense stand of reed canary grass. Note the almost total dependence on the previous year's growth for concealment. 124. only mallard nest not on the bank of a ditch was approximately 50 feet back from the nearest ditch. Again, the nest had been located at the base of a hardhack bush which was surrounded by, and supported, the previous year's growth of blue-joint grass. Both old mallard nests located in burned.cover were associated with the.outer edge of a blackberry clump and appear to have been originally located under the grass canopy that would have formed at the periphery of the vines. The average clutch size of the mallard nests under incubation was 10.8 eggs. In those nests that were successful (3) 100$ of the eggs hatched. One nest was destroyed by an unknown predator after being exposed by burning. The other nest.contained. only three eggs with no. down as the hen had deserted after being clipped by the mowing machine. (b) Teal Nesting Data In 1972, the cinnamon teal and blue-winged teal nesting period extended from May 2 to July 15 - a total of 75 days. Based on the age of twelve dif-. ferent broods, the peak of nest initiation occurred during the period May 23 to June 6. Subsequently, the.peak of hatching•occurred during the period June 24 to July 8 (Fig.VI-4). In 1973, far. fewer broods of cinnamon teal were seen and nest chronology is based on only five different broods. From these the. nesting period was calculated to be 88 days (May 6 to August I ). The peaks of nest initiation and nest hatching cannot be determined with any accuracy due to the small numbers of aged broods. AI I of the three cinnamon teal nests found were located in pure stands of grass spp. Two were situated beside roadside ditches in dense stands of reed canary grass. The other was in a smaI I clump of unidentified grass loca-ted in an old corn field. The average clutch size of these three nests was 125. 9.0 eggs'. .One of the three nests hatched successf u I I y whereas the other two were destroyed by mowing. The single green-winged teal nest found was on a ditchbank and utilized a sparse growth of bluejoint associated with stunted poplar and willow as a nest site. (c) Wood Duck Nesting Data The nesting chronology of the wood duck in 1972 was derived from nine-teen wood duck nest boxes that produced young in, and adjacent to, area. The earliest nest initiated was on March 28 and the latest hatch was July 8 for a total elapsed nesting period of 103 days. The peak of nest initiation occurred during the week ending April 27, followed by a hatching peak during the week ending June 3 (Fig. VI-5). A second, smaller peak occurred during the week of June 24. Of 23 boxes for which data was availa-ble the average clutch size was calculated to be 11.3 eggs per nest. The average number of young leaving 27 boxes was 9.5 young per box. In 1973 only a relatively small number of the wood duck boxes in the area were checked - 36 as opposed to 114 in 1972. A total of .'17 of the 36 wood duck boxes had one or more wood duck eggs laid in them. Eight of these boxes contained six or fewer eggs and were either the result of hens indis-criminately dropping one or two eggs during nest box selection or an incom-plete clutch resulting from the nest box being usurped by starlings (Sturnus  vuI gari s). Four of the remaining nine boxes had four or more ducklings leave upon completion of incubation. The other five boxes contained either dump nests or were deserted for unknown reasons during some stage of incubation. Due to the relatively low utilization of these particular 36 boxes, data on . nesting .chronology of wood ducks in 1973 was based on back-dating 21 broods aged via the i r p I umage. deve I opment (Appendix 7)'. FIGURE V I - 5 - - W O O D DUCK HATCHING CURVES FOR PITT AND ALOUETTE POLDERS -1972 &1973 1972 — 1973 S WEEKS-ENDING 127. These caleulations revealed that nest initiation peaked during the week ending April 28, whereas the. peak hatch took pI ace week ending June 2 (•Fig.-VI.-5-). As in 1972, the hatching curve showed a d i st i net but smaller peak duri ng the week of July 7. The ear Ii est caIcuI ated nest start was.on April 4 and the latest known hatch came off July 21. These indicate a wood duck nesting season of 109 days in 1973. Data, on clutch size and. young per box was obtained by supplementing my data with results obtained . in a similar study elsewhere in the Lower Fraser Valley (Cerenzia and Glew, .1973). From these sources, an average clutch size of I 1.0 eggs per nest was calculated from which an average of- 10.I young per nest hatched. 6.2.3 Brood Data A total.of 24 broods were censused on the- six habitat types in 1972 compared to 20 broods on the same areas in .1973. On the areas censused in a similar manner (see Section 6.1.3), 83$ of the broods were encountered on the agricultural lands in 1972 and 95$ in 1973 (Table VI-5). Comparative surveys (see Section 6.1.3) on the two marsh areas revealed very.little pro-duction along the routes surveyed. Of the total broods seen in the. study area the primary species were mallard, cinnamon teal and wood duck with occasional broods of green-winged teal and blue-winged teal sighted during the two field seasons (Table VI-6-). In 1973, an additional segment of farmland, designated Ag. I - east, was in-cluded in the study area. The decision this was based on the sightings of a large number of broods in this area in the late summer of 1972. The total brood counts for the study area, including Ag. I - east, are presented in Table Vl-6. Broods were aged according to the seven sub-classes of Gollop and 128. Table V 1 — 5: Distribution of Brood Production in Study Area "Complete" Census Areas: 1972 1 973 Agricultural Lands 19 ( 83$) 18 ( 95$) Open Wild 1ands 3 ( 13$) .1 ( 5$) Dense Wild!ands 1 ( 4%) , - ( . ) Tota 1 23 (100$). 19 (100$) "Comparative" Census Area: Sturgeon Slough.Marsh - ( ). 1 (100$) Public Shooting Marsh 1. (100$) - ( ) • Total 1 (100$) 1 (100$) Table VI-6: Brood Counts in the Various Study Area - June, 1972 and Habitat Types of the' 1973 . Species , . . Ag. 1 Ag. 11 West East .' Open . Dense Wildlands Wildlands Sturgeon Slough Marsh Public Shooti ng • Marsh 1972 1973 1972 1973 1972 1973 1972 ' 1973 1972 1973 1972 1973 1972 1973 Mallard 2 5 - 3 2 1 - - - 1 Cinnamon Teal 3 1 1 2 1 - -Green-winged Teal - 1 - ' - -Blue-wi nged Tea 1 - - - ' • - - . - -Wood Duck 4 . 6 - 7 1 3 2 1 1 -B.W. or Cm. Tea 1 2 - - - -Uniden, Puddle Duck - - - , - - " 1 ; --Tota1s 9 12 - 8. 10 6 3 1 1 . 1 1 VO 130. Marshall (1954). Where a large enough sample size was obtained, average ,r brood size at hatching and in successive age classes was calculated. (Table VI-7). During the two year period the average mallard brood-was reduced • 53.5$. from'the time of hatching to the last sub-class before flying. Cinna-mon teal broods were.a I so reduced considerably, undergoing an average reduc-tion in SJze from hatching to flying of 66.5$. Data on reduction'in brood size of wood duck from hatching to Class III birds is difficult to obtain due to the early disintegration .of brood bonds in this species (McGilvrey, 1969). However, ' it is possibIe to calculate a decrease in brood size, from hatching through Class I of 52.5$ in 1973. , . Despite the intensity of the survey methods used in Ag. I, Ag. II, Open Wildlands and Dense Wildlands, the brood counts reflect only the mini-mum number of broods actually present. Several instances were recorded to illustrate this contention. On June 19, 1972 a brood survey was conducted on the east bank of Sturgeon Slough. The habitat here considted of a 60 to I 00 feet w i de str i p of Carex spp - J uncus ba11i cus fIooded to a depth of approximately 1 foot. One observer walked through this cover and recorded four broods. The area was then immediately re-surveyed, using three observers, walking abreast and 15 feet apart, and a dog. This time the-four originaI •broods, plus three more, were sighted. Simi l.arly, on June 23, 1973 an attempt was made' to catch two broods of mallard I? hours after the area in which they were located had been completely surveyed. No mallards were caught but the dog did flush out a brood of Class la cinnamon teal that had not-been seen earlier. These, plus other similar instances, confirm the contention that the production of waterfowI,'as measured by the brood counts, is a minimum figure. 131 Table.VI-7 : Duckling Survival Through Successive Age Classes - Pitt Val ley, 1972 and 1.973 SPECIES Age Class Ma 11ard BW/Gr. Teal . Wood Duck 1972 973 1972 1973 1972 1973 At Hatch ng 10.8* 0.8* 9.0* 9.0* 9.5 (27) 10.1 (33) Class 1 8.0 (5) 6.2 (10) 6.0 (5) 6.3 (3) 7.0 (7) . 5.3 ( 12) . Class C lass 1 1 •1 1. 6.6 (6) f 5.0 (7) 6.0 (7.0) -5.1 (13) * combined avgs. for 972 and 1973 •> Class 1 1 and III combined C ) number of broods in average 132. . ' . 6.2.4 Brood Movements In all the habitat units, except the Sturgeon Slough Marsh and wildlands and the Public Shooting Marsh, the bulk of the water areas con-sist of drainage ditches. The ditches, in most cases, interconnect in a manner that facilitates maximum drainage. As such- these ditches, in effect, are inviting "highways" to the highly mobile broods of waterfowl. Several observations can be cited that indicate considerable movement of broods probably occurs. During.the second 1973 brood.count 13. broods of wood duck were seen on Ag. I - West and East. During this breeding season there were a total of 19 wood duck boxes on this area or immediately adjacent to i t . Of these, two produced broods and the rest contained either deserted wood duck clutches or active starling nests. Therefore, the remaining eleven broods of wood duck censused during the survey must have been hatched either in naturaI cavities on the habitat unit or in a location outside of the study area that provided the required nesting site's. Due to a lack of suit-able trees no natural cavities were known to exist on the habitat unit during this time. However, approximately one mile upstream, MO boxes-were erected on, and adjacent to, the South Alouette River. Of these boxes, 27 produced broods which, according to the landowner, soon left the immediate area of hatching. As.few broods were subsequently seen in ditches adja-cent to the nest box project, it is assumed that the bulk of them left the area by the only other available waterway, namely, the South Alouette River. It is suggested that this could well be one source of the "non-local" wood duck broods seen on the Ag. I habitat area further downstream.. During both years of the study the advent of the spring freshet 133. resulted in a marked response by duck broods. This involved a definite movement to water areas fringed by vegetation temporarily inundated by floodwaters. These areas were of two types. One type was^the remnants of old tidal channels that, due to dyking and drainage, are bordered with emergent, primarily Carex spps., in what was formerIy.channeI bed. Upon flooding this dense mat of vegetation apparently provides both concealment and a source in the suddenly available terrestrial invertebrates and plant seeds. Several instances illustrating this movement were noted. On June.17, 1972, 7 of TO broods counted on Ag. I - West were found in Midden Slough, which had flooded its banks.and created a band of partially submerged Carex spp. on its north bank. On June 27, 1972, a similar survey resulted in six broods being counted.on-Ag. I - West of which none were seen i n the Midden Slough. The most obvious change that had occurred in the time between the two surveys was a.considerable lowering of the water-tab Ie. throughout the area resulting in little or no fIooded Carex spp. along Midden Slough.. • A similar brood response occurs when the North Alouette River floods from dyke to dyke. This creates many acres of flooded brush, pre-dominately hardhack, and grasses, the latter consisting mainly of reed canary grass and blue-joint (see Fig. VI-7). On May 12, 1973, at which time the river was sti Ii restricted to its main channel, a brood count, on the adjacent Ag. I - West showed at least -six'ma I lard broods present in the ditches and sloughs of the farm, and none on the river. By May 25, 1973, the river had flooded the bankside vegetation between the dykes. Another brood count was taken which VeveaIed five mallard broods in the flooded vege-tation of the river and only two mallard broods in the ditches of the farm. F i g u r e VI-7: Brood c o v e r c r e a t e d a l o n g t h e N o r t h A l o u e t t e R i v e r , June, 1973. By.. June 23, 1973, the river had returned to its regular channel, which contains li t t l e , if any,emergent vegetation. Conversely, a brood count on Ag. I - West on this date showed five broods of mallard present, all of them in the ditches and sloughs of the farmland. In 1973 this movement was most apparent in the mallard broods. At the time of high water in the river the bulk of the wood duck had not yet hatched (see Fig. Vl-5),and the limited amount of teal data suggested that incubation.was s t i l l in progress in this species. In 1972, high.water s t i l l existed during and after the peak wood duck hatch. Thus, both mallards and wood duck broods showed an apparent response to short-term creation of suitable brood cover by moving from the ditches and sloughs of the farmland to the river and then presumably returning to the ditches, etc. once rec- . eding water levels in the river eliminated that area as brood rearing habi-tat. Similar response by predominateIy mallard and wood duck broods to flood-created brood habitat wa.s noted in the Ag. II and Open Wildlands habi-tat units in both years of the study. One final observation should suffice to illustrate the mobility of ducklings and. the role played in this activity by the extensive network of ditches throughout the study area. On July 17, 1973, a Class- I la wood duck was captured in a floating bait trap in the south-west corner of the Sturgeon Slough Marsh and subsequently banded. Seven days later this same, bird was re-trapped at another banding location approximately 1.3 miles south-west of the original capture site. To reach this site,, it was necessary for the duckling to swim almost exactly two miles along drain-age ditches leading from the marsh. 136. 6.2.5 Predation The results in this sect ion shou I d be interpreted keeping in mind that, in most cases., it is not possible to determine if one has found, the results of a predator kill or merely the results of scavenging by a poten-tial predator. Nevertheless, a record of all such occurrences, together with sightings of potential predators and, very occasionaI Iy, actual instances of predation, permit at least a subjective evaIuation. of possible predation pressure. Two instances of poss.i b I e . p'redat ion were documented in "1972 and nine in 1973 (Table V I — 8). In addition, there were thirteen sightings of potential predators during the same time period (Table VI-9). With one exception these do not include sightings of crows (Corvus spp.), red-tailed hawks (Buteo jamaicensis), marsh hawks. (Cireus cyaneus), or bald eagles (Haliaeetus IeucocephaI us), all of which nest in the area. (a) Avian Predators: The number of nesting crows is unknown but counts taken in May and June in the agricultural areas averaged 30 to 40 birds. Crows were seldom seen in any of the undeveloped areas with the exception of the Sturgeon Slough Marsh and the Public Shooting Marsh. In these, most of the sightings occurred during late April and early May, at which time the very low waters in the marsh made frogs, sluggish from .hibernation, an easy prey. Four active red-tailed hawk eyries were located on or adjacent to the study area in 1972 whereas three were known to be active in 1973. No marsh hawk nests were located but occasional sightings' of both females and the males of this species were made throughout spring and summer. At least of bald, eagles nested along the eastern periphery of the Sturgeon Slough Marsh in 1972 and 1973. Table VI-8: Instances of Possible Predation In Study Area - 1972 -1973 Date Habitat Unit Prey Circumstances Po? ,slble Predator 5-•6-72 Open Wldld. Adult M. Wood Duck Feathers plucked from breast; breast partially eaton.. Raptor 6-•27-72 Ag. 1 - west Cl . 1 ducklIng Mink carrying downy duel king approx. 20 yd. from Cln. Teal 1 Cl . la brood. Mamma 1 4--14-73 Open Wldld. Adult M. Green-winged Tea 1 Large ptle of. feathers and down but no carcass. Raptor 4-28-73 Ag. 1 west — Large mink being distracted by F. mallard as If attempted to reach nearby brood. Mamma 1 4-•28-73 ' Ag. II Adult F. Mai lard Breasts and lower portion of neck plucked and eaten. Two Cl. la ducklings peeping in adjacent ditch. Red-tailed Hawk circling overhead. Raptor • 5--21-73 Open Wldld. Fgg Crow flew across the road carrying what appeared to be either a teal or pheasant egg. Avian 5--25-73 Ag. 1 - west M. pheasant Lge. number of cock pheasant feathers scattered around edge of cornfield. Raptor 5--25-73 Ag. II Ruffed Grouse Lge. pile of feathers plus bits of Intestine and the crop; appeared fresh. Approx. 1 mile south of F. mallard - 4-28-73. Raptor 5--30-73 Ag. I - west Rob I n Red-tailed Hawk seized bird from cornfield .Raptor 7--17-73 Pub 1Ic Shooting Marsh Cl . 1 la Wood Duck Feathers In a pile and appear to have heen plucked - no skin attached. En-trails not eaten but rest of ccs. gone. Raptor 8--23-73 Ag. 1 - eabT Cl. 1 lb Cln. or B.W. Teal Duck feathers, down & small amount of bone scattered at base of fence post; some small feathers & blood stained top of post. Raptor Table VI-9: Sighting of Potential Predators in Study Area - 1972, 1973 Date Habitat . Unit . Predator Sighted Circumstances 5 -14-72 Ag. II Short-tailed Weasel . Crossed road in front of vehicle. 5-24-72 , Open WIdld. Short-tailed Weasel Crossed road in f r o n t of vehicle. 7-19-72 Ag. 1 1 Red Fox Flushed in rough pasture. 2-23-72 Open WIdld. Raccoon In large cottonv/ood tree. . 4-28-73 Ag. 1 - west Raccoon In. large Cottonwood adjacent to 4-28-73 Ag. 1 - west Coyote Loping through rough pasture adjacent to Midden ST. 5-12-73 Ag. 1 - west Coyote In rough pasture adjacent to Midden SI. 5-25-73 Ag. II Coyote in rough pasture east of Sturgeon Slough. 6-9-73 Dense WIdld. River Otter (3) in main south-north ditch. Lots of scats and . flattened grass in vicinity. 6-18-73 Ag. 1 - west Coyote Hunting in rough pasture east of Midden SI. 7-5-73 Public Shooting Marsh Red Fox Sitting on the dam. 7-12-73, Main Marsh River Otter (2) Swimming in channel north of Hobb's blind. 7-24-73 Open WIdld. Short-tailed Weasel Crossed road in front of vehicle. co I 39. (b) Mammalian Predators: Tracks of raccoon (Procyon lotor), fox (VuI pes fulva), and coyote (Can i s Iatrans) were commonly seen throughout the study area during both field seasons. Raccoon activity was particularly evident along ditch banks, sloughs and pond edges. The scats and tracks of black bear were not uncommon in the vicinity of the Sturgeon Slough marsh and on two occasions, sight-ings of individual animals.were made. One bear scat examined on May 24, 1972 was' found to contain unidentified eggshell, the fragments of which were large enough to be from a grouse or sma I I. spec i es of duck. Another qualitative case of predation was found in the examination of nine River Otter scats collected in.Ag. I - West on June 27, 1973. Five of these scats contained identifiable remains of fIightI ess duck Iings ranging from downies to feathered birds. How many otters were represented by these scats i s unknown. Two instances of predation on duck nests were documented. The first involved the incomplete clutch; of three eggs on Ag. I - West that were deserted after the hen was hit by the mower. The nest was. periodically checked thereafter and one month later, on May 12, 1973, one egg was re-moved and another partially broken.' The second instance involved a mallard nest that was incubated after the nest and eggs were scorched by a grass fire. Approximate!y.two weeks after the fire, the nest was destroyed and some of the egg. remnants were found along a ditch 35 yards north of the nest site. In both cases, the predator involved was unknown. 6.2.6 Fall and Winter Movement of Local Ducks During the 1972 field season banding operations were considered of secondary importance and were only carried out incidental to other facets 140. of/the fie Idwork. . Nevertheless, a total of fourteen flightless yoUng were caught by a retriever, banded and released. These fourteen birds consisted of twelve mallard, one wood duck and one cinnamon or blue-winged teal. A total of 215 ducks were banded in the study area between June 16, 1973 and August 23, 1973. Of those, 176 were livetrapped and 39 were caught using a retriever. The species breakdown of the total birds banded was as follows: 143 wood duck, .59 mallard, 4 cinnamon teal and one green-winged teal. In this study these birds, consisting, of breeders, young of the year and mouIters, were designated as local ducks. In addition to the aforementioned'birds,'a. total of 104 wood duck, were trapped adjacent to the study area on October 14, 1973. Unfortunately, it was not .possibIe to determine the origin of most of these latter birds. Godfrey (1966) includes part of the Queen Charlotte Islands and all of Vancouver Island within the breeding range of wood ducks. Thus, it was possible that an unknown number of these birds could be non-residents mig-rating through the study area. However, among the.104 birds were five that /had been banded at this trap location in February, 1972. In addition, . repeated observations by myself and the landowner, indicated that the trapped birds plus those remaining free would closely approximate the num-ber known to have been utilizing the area since late summer. Thus, based on these two criteria, I feel confident in adjudging most if not all these b i rds as bei ng of I oca I ori g i n. . A final source of data were the' 121 wood duck banded and released at the above location on February II, 1972. These were hand-reared birds born the previous summer and released for propagation purposes. Therefore, though technically second-year birds, they would not have been mig-rate until their second autumn. Hence, I would expect band returns of those 141 . to,reflect closely the dispersal of juveniles rather than that of exper-ienced adults. In summary then, we could anticipate band returns based on a total of 446 ducks consisting of the following species:. 369. wood duck, 71 mallard, 5 cinnamon or blue-winged teal and I green-winged teal. To the middle of June, 1.973, a tota I of 33 fall and winter band returns had been received consisting of 29 direct or first year recoveries and 4 second year recoveries. A breakdown of these returns to species, and age is given in Table VI-IO. Of the 8 direct recoveries of mallards, 5 were from the Pitt Valley, 2 from the Fraser VaI ley and I from Washington. All the recoveries.from B.C. were from birds shot during the first.eight days of hunting in the respective years. The recovery from Washington was taken October 24, 1973. If the direct recoveries from both years are-.combined-with-second year recoveries from the 1972 banding then data is available on fourteen adults and fourteen juvenile wood ducks. The spatial distribution of these .recover i es. .i s shown in Table V l - l l . Examination of the date of recovery for the adult wood ducks reveals that all of the seven birds taken in the Pitt Valley were shot prior to the end.of October and five of these during the first nine days of the hunting season. The adult shot m the Fraser marshes.was taken in December, 1973. However, of the three adults shots in the United States, the earliest reported was November 25, 1973 and the other two were shot i.n December, 1973. A somewhat reverse distribution, from a temporal standpoint, is apparent in the juvenile wood duck recoveries. Of the five brids shot locally, only one was taken after the end of October. Conversely, of the eight birds taken in Oregon and California for which re-covery dates are available, two were taken during the last week of October 142. Table VI-IO: Distribution of Direct.and Indirect Band Recoveries According to Species and Age Pitt Valley, 1972 and 1973 Species Ma I lard: 1972 1973 Tot a I s - Total. Banded A. J 18 18 12 41 53 Years 0-1 1 - 2 2 - 3 A. J. . 7 8 Wood Duck: 1972 1973 101 122 146 - • 4 7 10 TotaIs 101 268 7 14 Table Vl-I 1 : Location of Loca 1'ly-ra I sed Wood Duck Recoveries According to Age Class - 1972 and. 1973 Age Class Pitt Fraser Valley. Valley Oregon California Total Adults 7 1 2 1 II J uven i1es . 5 - 5 4 , 1 4 ' 143. and ,five of the remaining six after the 28th of November. No recoveries of banded teal were made, undoubtedly due to the very.smalI number banded. 6.2.7 Hunting Effort Hunting is conducted on both private and public lands in the study area. During the 1972 and 1973 hunting seasons approximateIy 7,I 00 acres were leased to six private hunting clubs, some 80 acres were closed to hunting by the owner., and 582 publicly owned acres were open to all .hunters (see Fig. VI-8). The membership of each of the clubs, and the acreage controlled by that club, are listed in Table VI-12. In the case of some clubs, members •are also permitted to take guests shooting and this may increase the overall hunting effort in these areas slightly. Finally, there is a definite poach-ing presence, particularly on the Mallard Gun Club and the Sturgeon Slough Gun Club, that undoubtedly contributes to the overall hunting effort within the Pitt Valley. Data detailing average hunter use for the Public Shooting marsh were not available. However, some idea of relative use between this area and the. adjacent Sturgeon Slough. Club on the first day of hunting season is shown in Table VI-13. In addition, our observations over two hunting seasons indi-cate that' only a si ightly lower ratio of use is maintained until the November II long weekend of each year. After that time, hunter use of the public marsh is sharply reduced. .In addition to limiting its membership, the Sturgeon Slough Club also attempts to manipulate the hunting effort within the club itself. It does this by allowing continuous shooting for the first six days, no shooting on the seventh and thereafter, until November II shooting may take place only on Saturdays, Sundays, Tuesdays and Wednesdays. Likewise, members may not bring 145. •Table V I — I 2: Membership of and Acreage Controlled by Gun Clubs in the Pitt Valley - 1972 and 1973 No. Members No. -' Acres Acres/Hunter Alouette Gun Club 25 1 , 140 45.5 Mounta i nv i ew Gun C l.ub 5 ' - ,185 37.0 Sturgeon SI. Gun Club 20 - 1972 24 - 1973 3,475 3,475 173.0 145.0 WiIson SI. Gun Club 30 1 , 1 85 •39.5 Mai lard.Gun-Club 2 565 282.0 L. Mainland Zone ? 600 7, 150 ? Table V1-13 : Hunting Effort on "Opening Day" Areas of Pitt Polder - 1972 and in Select 1973 No. Hunters Acres/Hunters Acreage 1972 1973 1972 1973 Sturgeon SI. Club 800.0* 13 12 61.5 66.6 Public Shooting Marsh 582.0 III 120 5.2 4.8 *Total- club acreage, was restru.cted to is 3,475 acres but hunting 800 acre marsh. • 146. guests until after the ninth day of the season. For comparative purposes, a shooting club, Coniagas Ranches, located adjacent to the southern boundary of the study area, has been included, in this and the following sections. 6.2.8 Hunting Success On the first day of the hunting season in 1972, 180 hunters were pro-cessed through the check station. Of these, III (66.4$)had been hunting in the Public Shooting Marsh, 13 (7.2$) on the Sturgeon Slough Club lease and '. 56 (26.4$) eIsewhere • in the Pitt Polder. Of these latter, 13 were from other clubs in the area and the rest were members of the general pub Iic.hunting on, or outside of, the dykes. In addition, 9 hunters were active at -Coniagas Ranches on this date. On the first day of the 1973 hunting season a total of 230 hunters, were known to have hunted in Pitt Polder or. on the adjacent river or lake. Of these 120 (55.0$) had been hunting in the.Pub Iic Shooting.Marsh, 12 (5.7$) on the Sturgeon Slough Gun Club lease and the remaining 86 (39.3$) elsewhere in the Pitt. Polder.' Of the latter, 24 were from other clubs and 62 were members of the general public utilizing unposted dykes and adjacent- un^ dyked. areas. At Coniagas Ranches, a total of 13 individuals hunted waterfowl on the opening day. The hunting success rate, expressed as d.ucks bagged per hunter day,- for these various factions of the hunting public, are given in Table VI-14. Attempts at monitoring the hunting success over the entire season met with varied success. Three of the five hunting clubs contacted made a con-scientous effort to record the requested data, the data of another was not recorded reguIarl y and the fifth apparently made little effort at a l l . Of the .20 hunters selected at random (see Section 6.1.6), 17 initially expressed interest in participating in the survey. Of.these, 7 returned completed forms Table VI-14: Hunting Success of Club and Non-C1ub Members on "Opening Day" - Pitt Valley, 1972 and 1973 Area Hunted Ducks Bagge d/Hunter Day 1972 1973 1 . Public Shooting Marsh .64 .77 2. Pitt Polder 1 .00* .80* 3. Sturgeon SI. Game Club 4.23. .6.66 4. Con iagas Ranches ' 2.66 ,3.77 * excludes Sturgeon SI. Club members, but includes the Public Shooting Marsh Table V I — I 5: Hunting Success of Club and Non-Club Members over the Entire Waterfowl Season - Pitt Valley, 1972 and 1973 Area Hunted Ducks Bagged/Hunter Day 1972 .1973 J. Public Shooting Marsh - .34 2. Sturgeon SI. Game Club 4.57 3.90 . 3. Coniagas Ranches 2.20 3.74 148. at the end of the hunting season. However, as 2 of' these hunted regularly on one of. the clubs, their data were deleted so that a better idea of the success of the hunters not attached to clubs could be determined. These data are'presented in.Table VI — 15. 6.2.9 Species Composition of the Kill Six clubs in or adjacent to the study area were asked to record the' number of waterfowl taken by their members in 1972 and 1973. The data from two of these, the Sturgeon Slough Game Club and Coniagas Ranches, were selec-ted for discussion due, in part, to the large number of birds bagged by these clubs. For 1972, these amounted to 596 waterfowl recorded for the Sturgeon Slough Club and 99 for Coniagas Ranches. In 1973, the recorded kill for these clubs was 541 and 715 waterfowl respectively. The variation in the kill between 1972 and 1973 at Conigias Ranches reflected, in part, creation of additional waterfowl habitat at this locale in. 1973. In addition to these sources, data on 132 waterfowl harvested in the Pitt Valley were obtained in the National Wing Survey in 1972. In 1973, the same source permitted analysis of 159 ducks and geese taken in the study area. Compilation of these totals revealed the occurrence of 20 species of waterfowl in hunters' bags in the study area. However, many of these were represented infrequently with the result that four species contributed the largest pro-portion of the k i l l . These were mallard, pintail (Anas acuta), wi dgeon, and green-winged teal (see Table Vl-16). In addition to these, and because of local management interest, the numerical contribution of wood duck and gadwall were also included as separate entities. During both years of the study the proportion of.each species of waterfowl processed through the opening day check station was calculated. These are also presented in Table Vl-16 for comparison with the season-long figures. •Tab e V 1 - 16: Spec Compos i t ion of Waterfowl Kill in the Pitt Valley - 1972 and 1973 % Occurrence Mallard Pintail ... , Green-w WjjJseon . T e a | i nged Wood Duck Gadwa11 Others 1972 Con i agas Ranches 16.0 ( 4.2) 13.0 (20.8) 2.0 ( -)' 49.0 (58.3) 18.0 (12.5) - (- ) , 2.0 (4.2) Sturgeon SI . Club 33.0 (80.0) 4.5 ( 1 .8) 45.3 (5.5) 14.1 (9.1) .6 (.1.8) 2.7 (1 .8) - ( - ) Pitt Val 1 ey 39.6 (19.2) 13.8 (13.2) 16.8 (10.8) 21.8 (38.9) 1.0 (10.2) 4.8 (1 .2) 2.2 (6.5) 1973 Con iagas Ranches 18.6 (24.5) 32.6 (28.5) 12. 1 ( - ) 29.7- (28.5) 2.8' (14.3) t F . ( - ) 4.2 (4.2) •Sturgeon SI. Club 46.5 (53.7) 17.2 (25.0) 20.3 (16.3) 7.2 ( - ) .7 ( 5.0) 6.5 ( - ) 1 .6 ( - > • Pitt Val 1 ey 27.0 (26.5) ' 14.5 (16.1) 20.4 (12.6) 25.6 (20.1) 2.5 ( 1 .5) 3.2 ( - )' 6.8 (17.2) ) % contr bution to Opening Day Kl I 1-150. 6.3.0 Discussion 6.3.1 Suitability of Habitat Types for Territory and Nesting There are two requirements necessary before an area can support a breeding population of waterfowl. The first is a suitable habitat and the other, pairs of ducks to establish territories in that habitat. Based on pair counts conducted within the habitat types (see Section 6.2.0), it appears that there is an adequate reservoir of ducks present in the sprin.g to meet the latter requirement. It remains, therefore, to assess the six habitat types in terms of their relative abilities to meet the requirements of territory establishment by breeding pairs. In waterfowl the function of. a. territory is to provide the drake's innate requirement for isolation from. sexuaI Iy active members of his own species., other than his mate, during one part of the reproductive cycle (Hochbaum, 1944). In the process of defending this territory the drake also defends his'mate-and the physical components of the territory. This leads to the question "What are the components of a territory?" Hochbaum described a territory as "... a specialized, p i ece of. terra i n in which four components must exist together: Water, loafing spot, nesting cover (adjacent or nearby) and food." Hence, an evaluation of an area's waterfowl production must also consider that area's ability to meet the four basic territorial requirements. The following discussion considers these requirements as they pertain to the.six habitat types being studied: AG. I (a) Water: The first territorial component, water, is. almost exclusively confined 151 to artificially created waterways, namely ditches (see Fig. VI-9). and borrow-p i ts... The one exception is the remnants of Midden Slough (see Fig. VI-IO), which now, in effect, serves as a form of drainage ditch. Pair and brood counts, revealed a surprising degree of acceptance of these waterways by the three common species of nesters. Hochbaum (194.4) also noted the heavy utilization of roadside ditches by both dabblers and divers at Delta, Manitoba.. Similarly, irrigation ditches were used extensively by mallards nesting in the Sacramento Valley (Earl, 1950). In the latter area ditches functioned as territories, loafing.areas and brood cover.during the early part of the hatching season. Defence of a territory, by the drake, is in response to a visual stimuli. Hence, shoreline with natural obstacles, that is: shrubs, emergent vegetation, small trees, ox-bows, etc., that limit the plane of sight of the drake, support more territorial pairs than long straight waterways, such as ditches. Earl (1950) calculated the average mallard territory on ditches in the Sacramento Valley to be 70 yards long. Extrapolation of this figure to the total miles of ditch in Ag. I indicates available territory for 438 pairs of mallards, if water surface is the sole criteria for territory establishment, lt i s . apparent from the pair counts (see Table Vl-I) that this area falls far short of the hypothesized maximum. This leads to two possibilities: (I) there are insufficient pairs to establish that many territories or (2) much of the ditch shoreline lacks some criteria of territory other than water. Although early spring counts did indicate fewer than 438 pairs of mallards available, I be-lieve that the second possibility governs the number of territories established in this habitat. A similar conclusion can be reached when territorial pairs of cinnamon teal are considered-. 152. Figure VI-9: Roadside ditch in Ag. I of the type utilized by territoria pa i rs. 153. (b) Loaf i ng S i'tes : Seemingly incongruous, the importance of loafing sites are often over-looked when considering the requirements of breeding waterfowl. Hochbaum (1944) used, such terms as "... an indispensable factor..."; not. accep-table as 'territory. "; and "... an innate requirementto'describe the importance of loafing sites. The same author noted both the abandonment and establishment of territories when loafing sites were respectively des-troyed or created. Quame and Grew'e, Jr. (1970) noted the greater use of a wafer area by breeding waterfowl due to the construction of artificial loafing sites when all natural sites were occupied. Loafing sites can take many forms including muskrat houses, matted aquatic vegetation, mud or sandbars, boulders or clumps of mud protruding from or adjacent to the water body, logs, pieces of driftwood, sloughed, ditchbank, etc. Yet one can search many hundreds of yards of ditch in Ag. I without finding anything resembling a haul-out location (Fig. VI-IJ). This reflects the preoccupation of the farmers with maintaining the drainage sys-tem at peak efficiency. Hence any artificial object, such as old fence posts, boulders,, logs, bales of hay, etc. are considered an impediment to water flow and hastily removed. Build-up of natural sites such as sandbars, vege-tation mats, etc. are controlled by drag-lining of ditches. Crumbling of ditchbanks due toerosion or at cattle watering locations create some loafing sites but not in large numbers. The horrow-pits bordering all. of the west section and a portion of the east section are of sufficient depth to preclude buildup of sand or mud bars and the like. However, these waterways are apparently maintained infrequently and many stretches of the borrow-pit bordering the North Alouette River feat-ure numerous logs, driftwood, and dead trees - all potentially good loafing Figure I f f — I I : Ditch in Ag. 1 showing lack of loafing stations along either the bank or in the ditch proper-I 55. sites. When the pits were formed during dyke-building, a thin strip of the originaI' sdi I running up the centre.of the pit was not removed. Although now heavily vegetated by Juricus spp., it offers some potential loafing sites. In summation, the paucity of loafing sites in many of the' waterways of Ag. I may contribute significantly to maintaining territorial establish-ment at its present level. Cc) Nesting Cover: Ducks are somewhat species specific in their selection of nesting cover. (Hochbaum, 1944). Hence, mallards often favour rank stands of dead,grass and/or herb spp. associated with shrubs and vines. Conversely, cinnamon and blue-winged teal prefer grassy type vegetation of the current year's growth. In.their Minnesota study, Quame and Grewe, Jr. (1970) noted that mallards preferred heavy sedge cover whereas blue-winged teal, nests were primarily located in cultivated areas. Mallards and cinnamon teal nesting at Humboldt Bay, CaIifornia showed a similar utilization of nesting cover (Wheeler, 1966). In this study,' the results of nest searches (see Section 6.2.2) revealed.a similar distribution of nests according to species of duck and vegetationaI cover. Selection of these covers may, however, refIect cover avaiIabiIity rather than cover preference (Gates, 1965). This stems from the chronology of nest-ing of the various species. Throughout its range the mallard is one of the . earliest ducks to nest (Munro, 1943). In. many areas, the current year's growth is barely underway and hence the.mallard must utilize the dead growth of the previous year (Keith, 1961). Conversely, cinnamon teal and the closely related blue-winged teal are among the latest nesting of puddle ducks (Harris, pers. comm.). In the study area peak nest initiation for cinnamon teal did 156. not'occur until late May in 1972 at which time roadside stands of reed-canary grass averaged 8 - 10 inches in height. Bennett (1938) noted -that;'bl'ue-winged teal started nest building when current year's growth of the preferred grasses ranged in height from 8 to 24'inches,"depending on species. In Minnesota, Moyle et a I (1964) found that a minimum height of 6 inches was necessary in alfalfa stands before bIue-winged tea I wouId.nest, in.them. The diversi.ty and type of' land uti I ization :• i n .Ag. I - West appears., provide numerous nesting opportunities for both mallard and teal.. The 2.9 miles of dyke is essentially vegetated with reed canary grass, interspersed' throughout by blackberry vines and elderberry bushes. Most ditches in the cropland consist of thick' stands of grass, predominantly reed canary grass, blackberry vines and shrubs. Ditches in the wildlands are heavily brushed to the top of the d itchbank-with dense stands of hardhack and thus provide little in the wayof suitable nesting cover. The road allowance on the west side-.of Neaves Road is vegetated a Imost enti re I y by reed canary grass, and is apparently favoured by nesting cinnamon teal. The east section of Ag. I is managed as a hay-pasture unit. The degree of cover interspersion so evident in the west section is noticeably reduced. Mowing of hay and subsequent grazing has reduced the incidence of heavy ditchbank cover. Nevertheless, the extensive acreage of hayfields appear favourable as tea I nesting cover and enough vines and shrubs persist along ditchbanks to provide a fair amount of potential nest sites for mallards. Hence, initial, consideration of nesting cover in the Ag. I habitat type would indicate that this criteria of territory establishment should not be limiting. Cd) Agriculture - Nesting Conflict: However,.the aforementioned evaluation must be modified in light of 157. several farming practices carried out each spring. i . Burning:. The first of .".these involves the annual burning of old plant growth along.dykes, ditches (see Fig. V1—12) and roadsides. In 1973 this practise had commenced on the study area by early February and was generally terminated by the end of that month, except for isolated cases Csee Fig. VI-13). In Ag. I - West, 2.9 miles of dyke and 250 yards of road-side, ditch were burned,, in addition to an I I.0 acre field containing rough pasture. This effectively removed a substantial portion of the nesting habitat required by mallards just prior to territory establishment. Burning in the east, section of Ag. I was negligible, probably rendered unnecessary by the reduced "wild" growth along the majority of ditches'. Such burning practices have ramifications other than that of the immediate removal of nesting cover on farmlands. Leopold (1933) noted, that since many waterfowl start nesting before the appearance of any new growth the presence of residual cover from the previous year not only permits .earlier nesting but also increases the period of time available for renesting. Keith (1961) stated that burning on his study area advanced spring, growth'-10 days, due largely to the removal of accumulated plant residue. Thus, one could surmise that, while such burning•removed potential ma I Lard habitat, it created additional cover for the later arriving teal. However, Glover (1956) found that blue-winged teal seldom nested in a burned-over area even after regeneration had occurred to the point where there was IittIe difference be-tween burned and unburned areas. At this latter stage the only apparent difference was the lack of accumulated plant residues at the soil, surface in the burned areas. As such material was used extensively in nest.construc-tion, its.removal may have forced the hen to nest elsewhere. Gates (1965) suggested that tangles of dead grass and weed stalks forming the Iifter con-F i g u r e V I - I 2 : P o t e n t i a l d i t c h b a n k n e s t i n g c o v e r d e s t r o y e d by e a r l y s p r i n g b u r n i n g . F i gure V I - I 3: M a l l a r d n e s t denuded of c o n c e a l i n g c o v e r by l a t e s p r i n g b u r n i n g . 159. tributed to high hatching success by offering concealment and prov i d i ng. the moisture and temperature regulation essentia I.for maximum egg hatchabiIity. i i . Cutting of Ditch-bank Vegetation: A second farming•practise, apparently restricted to Ag. i , involves the use of a tractor-mounted cutting bar to cut back ditchbank vegetation bordering all fields .in which crops are to be planted. The shears are set approximately one foot above the ground and severed vegetation • is.genera I Iy. suspended in a tangle of vines, shrubs and grass at about that height. Hence, the actual ground cover is little affected. However, when such.a practise is carried out' during:the egg-laying or incubation period, hens frightened from the nest, or clipped by. the cutter-bar, may subsequently desert. One such instance was recorded :in-" April of 1973. Due to the timing of this practise and the cover type involved, mallards-are the species primarily affected. i i i . Mowing: Three types of mowing occur in Ag. I. By far the most common is the'cutting of hay, predominantly in the east section of the habitat type. Only one cut is taken and this occurs over a two-week period starting in' early July. As previously mentioned, teal prefer such areas for nesting and thus could suffer the heaviest losses during haying opera-tions. In 1972., the peak cinnamon teal hatch occurred during the period June 23 to July 8. This would suggest that the bulk of the teal hatch should occur before mowing. Some cut fields were lightly searched but no destroyed hens . or.nests were found. Conversations with the tenant farmer revealed that although a number of pheasant nests, and some hens,, are destroyed each year, he has never seen a destroyed duck nest. The cutting of. silage in this habitat type was limited to 10.7 acres in 1972 and 12.6 acres in 1973. This occurs in "tired" pasture that has been 160. ploughed and reseeded to grass in the spring. Two, and sometimes three, cuts are made during the summer and the field is then used as a pasture in subsequent years. As noted by Moyle et al (1964) lands that have been'.rec-ently ploughed are lit t l e used by nesting ducks, presumably due to the absence of ground litter. This factor, plus the relatively small acreage involved, makes it unlikely that mowing for silage had much impact on nesting water-fowI• i n Ag. I. The third.type of mowing is carried out under contract to the Municip-ality of Pitt Meadows. It involves cutting the major road allowances, in many cases right to the edge of the ditchbank, throughout Alouette, and in part of Pitt, polders (see Fig. VI-14). In 1973, three or four cuts were made, depending on location. In Ag. I, a totaI of three were recorded. This practise, is apparently quite destructive to nesting cinnamon and blue-winged teal. One known nest was destroyed in this.manner in Ag. I (see Fig. VI-15) and another in Ag. II. I suspect a more concentrated search of similar nesting cover prior to cutting would have revealed additional nest destruction. The utilization of roadside cover by nesting waterfowl, particularly in areas undergoing intensive agricultural activities, is often out of proportion to .that cover's presence in an area (Evans and Wolfe, 1967). Therefore, this non-agricultural of destroying potential waterfowl nesting cover must be•considered as a contributor towards lowering the productivity of this and other agricultural habitat types. iv. Grazing: A final consideration in the su i tab i. I ify' of Ag. I as territory for breeding waterfowl is the grazing of cattle. The bulk of this occurs in the east section and in the pastures abutting Neaves Road and Midden Slough in the west section. Due to the mowing and subsequent grazing that occurs in these pastures, there is little buildup of the residual vegetation from previous seasons. . Therefore, it .is unlikely that many mall.ards nest in Figure VI —14: Destruction of Cinnamon and Blue-winged Teal nesting cover during height of nesting season. Yellow flag marks a nest previously undergoing i ncubat ion.• Figure VI-15: Cinnamon Teal nest destroyed by roadside mowing. 162. these locations. As many of these pastures are mowed before grazing commences, any teal nests located in them would be destroyed and cattIe tramp Iing would be of no significance. The exception could be the rough pastures in which hay is not cut prior to grazing. A more important factor arising from the presence of cattle may be the effect on pre-territoriaI pairs. Kirsch (1969) found that pairs were appar-ently disturbed by cattle and tended to move from areas in which cattle con-gregated or grazed. In a personal communication to the same author, Hammond stated that female ducks tended to avoid sites where cattle were present during the pre-nesting period and during the selection of nest sites. A similar reaction by ducks considering territory establishment in portions of . Ag. I would further lower that area's capabiI ity to'produce.waterfowl. (e) Food: Of the four basic territorial requirements perhaps the most nebulous to quantify is the role played by food. Hochbaum (1944.) felt that food was an important factor in the distribution of territorial pairs in the Delta Marsh of Manitoba. Noting the quick response of ducks to a sudden Iy'avaiIabIe source of food in the summer, Keith (1961) suggested,this as a means of at-tract * ng and holding a larger spring population on his.area. Spring feeding of mallards in Montana resulted in more numerous and better distributed nests on the Pablo Refuge (Girard,I 941). Similar results were obtained with black (Anas rubripes) and ring-necked (Aythya coI Iaris) ducks in Maine(MendaI I, 1949b). Casual examination of ditches in Ag. I - West in February, I 973 . rev.ea I ed a surprising amount of invertebrate activity considering the sparseness of the vegetation. Such organisms are probably of value to. incubating hens (Krull, 1970), especially in light of the high protein required at this time. Ditches not recently cleaned probably contain seeds of both aquatic and 163. t e r r e s t r i a l p l a n t s i n t h e i r s e d i m e n t s . H o w e v e r , i n t h e d e e p e r d i t c h e s a n d b o r r o w p i t s many o f t h e s e w o u l d be u n a v a i l a b l e t o d a b b l e r s . D u c k weed i s d i s f r i b u t e d s p o r a d i c a I Iy t h r o u g h o u t t h e d i t c h e s o f A g . I and.may. p l a y a r o l e i n m a i n t a i n i n g b r e e d i n g p a i r s o f d u c k s . S e v e r a l l o n g - t i m e r e s i d e n t s o f t h e a r e a m a i n t a i n t h a t , due t o t h e d i s -a p p e a r a n c e o f f o r m e r l y a b u n d a n t . s m a r t w e e d b e d s w i t h t h e a d v e n t o f r e c l a m a -t i o n , l a c k . o f n a t u r a l f o o d i s t h e f a c t o r r e s p o n s i b l e f o r t h e ' l o w number o f w a t e r f o w l p r e s e n t y e a r - r o u n d i n t h e s t u d y a r e a ( H a y w o o d , P o t t i n g e r - p e r s o n a l c o m m u n i c a t i o n s ) . Mr. Haywood r e p o r t e d a n o t i c e a b l e i n c r e a s e i n m a l l a r d b r o o d s on h i s p r o p e r t y when f a l l f e e d i n g f o r h u n t i n g p u r p o s e s was c a r r i e d o v e r i n t o t h e s p r i n g a f e w y e a r s ago.. In t h e same v e i n . , M u n r O ) ( l 9 4 3 ) f e l t t h a t t h e f e e d i n g o f . d u c k s by h u n t i n g c l u b s was p a r t o f t h e r e a s o n f o r an i n c r e a s e i n t h e l o c a l n e s t i n g . p o p u I a t i o n o f ma I I a r d s t h r o u g h o u t t h e L o w e r F r a s e r V a l l e y i n t h e l a t e t h i r t i e s . W h e t h e r t h e a m o u n t o f f o o d a v a i l a b l e i n t h e s p r i n g i s a f a c t o r i n -f l u e n c i n g t h e c u r r e n t l e v e l o f w a t e r f o w l p r o d u c t i v i t y i n A g . I , or a n y o t h e r h a b i t a t u n i t i n t h e s t u d y a r e a f o r t h a t m a t t e r , i s o p e n t o * c o n j e c t u r e . M o r e d e f i n i t e c o n c l u s i o n s c o u I d be o b t a i n e d by c o n d u c t i n g e x p e r i m e n t a l s p r i n g f e e d i n g i n v a r i o u s h a b i t a t t y p e s and n o t i n g t h e s u b s e q u e n t p r o d u c t i v i t y i n l i g h t o f t h a t e s t a b I i s h e d by t h e c u r r e n t s t u d y . ( f ) Wood D u c k R e q u i r e m e n t : : i t i s t o be n o t e d t h a t t h e d i s c u s s i o n t o t h i s p o i n t h a s b e e n b e r e f t o f r e f e r e n c e o f t h e s u i t a b i l i t y o f A g . I i n p r o v i d i n g t h e t e r r i t o r i a I requir-m e n t s o f wood d u c k s . T h i s r e f l e c t s t h e a p p a r e n t l y m i n o r r o l e t h a t t e r r i t o r -i a l i s m p l a y s v i n t h e b r e e d i n g c y c l e o f wood d u c k s ( J o n e s - a n d L e o p o l d , 1 9 6 7 ) . A s n o t e d by Grice and R o g e r s ( 1 9 6 5 ) , i n t h i s s p e c i e s "... t h e o v e r r i d i n g r e q u i r e m e n t f o r n e s t i n g i s a s u i t a b l e n a t u r a l c a v i t y . " In t h e a b s e n c e o f 164. n a t u r a l c a v i t i e s , a s i m i I a r cone I us ion can be drawn w i t h r e s p e c t t o a r t i f i c -i a l n e s t s i t e s . Few n a t u r a l c a v i t i e s a r e p r e s e n t i n Ag. I, w i t h a l m o s t a l l wood duck n e s t i n g c o n f i n e d . t o n e s t boxes. By j u d i c i o u s placement o f t h e s e s t r u c t u r e s , t h e d i s t r i b u t i o n o f wood duck p a i r s has been m a n i p u l a t e d t o e n s u r e u t i l i z a t i o n o f t h a t h a b i t a t w i t h i n Ag. I most l i k e l y t o meet t h e i r needs,, i . e . w a t e r , l o a f i n g s i t e s , f o o d , e t c . Hence, a t t h e p r e s e n t d e n s i t y of a r t i f i c i a l n e s t i n g s i t e s any l i m i t a t i o n s on wood duck p r o d u c t i o n i n Ag. I r e f l e c t s f a c t o r s o t h e r t h a n t h o s e n e c e s s a r y t o a t t r a c t . a n d m a i n t a i n b r e e d i n g p a i r s . AG.I I . ' ' The d r a s t i c drop i n p a i r and brood p r o d u c t i v i t y (see T a b l e s V l - 3 and 6) between Ag. I and.Ag. II h a b i t a t t y p e s r e f l e c t s t h e change from a d i v -e r s i f i e d c r o p - h a y - g r a z i n g t y p e a g r i c u l t u r e i n t h e forme r t o t h e e s s e n t i a l l y mono-crop s t e r i l i t y o f d a i r y f a r m i n g i n t h e l a t t e r . . In 1972 and 1973, 83$ of t h e land a r e a in. Ag. II managed f o r a g r i c u l t u r e was i n p a s t u r e and used s o l e l y ' f o r g r a z i n g d a i r y cows and t h e p r o d u c t i o n o f s i l a g e . (a) . Water: . • . '. The c h o i c e o f wa t e r a r e a s f o r t e r r i t o r y e s t a b l i s h m e n t i n Ag. II i s now r e s t r i c t e d e n t i r e l y t o d i t c h e s . P r i o r t o a g r i c u l t u r a l . , development, W i l s o n ' s and S t u r g e o n S l o u g h s were p r o b a b l y a t t r a c t i v e t o w a t e r f o w l t h r o u g h o u t much of t h e i r l e n g t h . Due t o c h a n n e l i z a t i o n t h e y a r e tod a y l i t t l e more tha n l a r g e d r a i n a g e d i t c h e s . Growth of a q u a t i c s in t h e s m a l l e r d i t c h e s and p a r t s o f Sturgeo n S l o u g h appear s i m i l a r i n d e n s i t y and d i v e r s i t y as t h a t found i n Ag. I. However, W i l s o n ' s S l o u g h i s a p p a r e n t l y d e v o i d o f a q u a t i c v e g e t a t i o n g r o w th i n q u a n t i t i e s t o be of much v a l u e t o w a t e r f o w l . 165. (b) Loafing Sites: As in Ag. |., the maintenance of ditches to provide efficient drainage leaves little in the way ofi loafing sites for the territorial species of waterfowl. Occasional clumps of cattail torn free from the substrate pro-vide some poss i b i I. i t ies in Sturgeon Slough as does the infrequent piece of plank or fence post. Occasional tussocks, the result of grazing, exist along both Wilson and Sturgeon sloughs. However, the presence of cattle and the lack of adjacent aquatic plant cover make these tussocks of quest-ionable value as loafing sites. (c) Nesting Cover: Typically, pasture areas are virtually devoid of the rank growths of shrubs, vines and grasses necessary for nesting mallards.. Most ditchbanks are grazed down to the waterline (see Fig. Vl-16). • Others may be marked by a thin band of J uncus spp. (see Fig. VI-17) which is unsuitable as nesting cover due to frequent, flooding. Although bounded on three sides by roads, a substantial portion of the cover along the road allowance is annually removed by mowing and firing. What lit t l e nesting cover for mallards that does exist is found along the west bank of Sturgeon Slough. A large portion of this is associated with a 3.1. acre stand of cattail. A band of "wild" growth consisting of rushes, grass and herbs, interspersed with the occasion-al shrub, exists between the cattail, which borders the slough, and the pas-ture. Similar small patches of matted grasses and rushes can be found in a thin band bordering the west bank of the slough. On the east bank of Stur-geon Slough 123.0 acres'.of rough pasture offers a variety of cover opportun-ities for ma I I ards. However; its. vaIue, is diminished somewhat by a lack of associated water areas. Cover opportunities for nesting cinnamon teal are even more restricted. 166. F i g u r e V I - 1 6 : B a n k s o f W i l s o n S l o u g h s h o w i n g c o m p l e t e r e m o v a l o f p o t e n t i a l n e s t i n g c o v e r by g r a z i n g . Figure VI-17: Though shunned by grazing cattle, Juncus spp. provide little nesting opportunity due to frequent flooding. 167. Up to five cuts of silage per year from some pastures seldom permits the vegetation to reach a height. conducive to nesting by this species. Should such attempts be made they stand, little chance of success the recur-rent mowing. Pastures cut less frequently are used for rotational' grazing of dairy cows and hence seldom achieve a suitab Ie'cover height for nesting. 1 suspect the bulk of the teal producing broods in this area do so by u t i l -izing the road allowances for nesting. These are mowed.3 to 4 times per year also, but in a less efficient manner than the pastures. Successful nesters are apparently those locating very close to the ditch bank or in strips of vegetation missed by the mowers. Only two wood duck boxes have been erected in this area .and the virtual absence of large softwood, spp. of trees precludes the presence of many natural nesting sites for this species. (d) Food: As in Ag. I, the status of food as a factor in the distribution of breeding pairs in this habitat type is difficult to ascertain without further study. DENSE WILDLANDS Although dissimilar in almost every other biotic facet, this habitat type and the agricultural lands share one common characteristic. AlI three depend on a. system of drainage ditches and pumps to control' the water table. Hence, all three are similar in that water areas for potential breeders are largely confined to ditches. (a) Water: In the ditches themselves, there are profound, and noticeabIe differences. With the infrequent exception, almost impenetrable stands of hardhack line 168. both .banks of most ditches (see Fig. VI-18). In many instances these shrubs form a complete canopy above.the water surface. Years of accumulated leaf-f a l l , blackened but virtually undecayed, line the- bottom of each ditch. These, in conjunction with the shading effect of the canopy, permit little aquatic vegetation to become established. Cursory examination reveals l i t t l e , in the way of invertebrate . I ife. The.water level in many of the ditches is generally higher than that found in the Ag. areas. In many cases this condi-tion stems from the continual building of dams by beaver (Castor canadensis). Though.these are periodically removed by the landowner, new ones soon appear. Another type of waterbody occurs in the SweetgaIe-Sphagnum communities (see Appendix I). Fall and winter rains accumulate in natural depresssions thus . forming.smaI I ponds, generally located in the centre of the community (see Fig. VI-19). These water bodies may persist into early summer in some years, depending on the climatic conditions. Hence, occasional broods of mallards may be raised there but I suspect these are number. According to. mem-bers of the guri-club leasing this land, a small, pond has been artificially created in. one hardhack thicket. However, I was unable to locate this pond and feel that its described location precludes any extensive use by breeding waterfowI. (b) Loafing Sites With the exception of the wood duck, puddle ducks seem to prefer I oafing sites located in a relatively open situation. This permits maximum visibility for territorial defence by the male, enables early detection of potential pre-dators or intruders, and allows the pair to loaf and sleep in the' rapidly warming sun of spring'and early summer. Along most of the.regular ditches such preferences can only be exercised in the occasional openings present in the. ditchbank shrubbery. The greater width of the main north-south drainage F i g u r e VI-18: Impenetrable growth of hardhack a l o n g d i t c h b a n k s in t h e Dense W i l d l a n d s . F i g u r e VI-19: S e a s o n a l l y f l o o d e d "peat pond" t y p i c a l o f t h e SweetgaIe-Sphagnum community - Dense W i l d l a n d s . 170. ditch, in conjunction with the intermittent presence of reed canary grass stands along the ditchbank, provides some.potentiaI opportunities. How-ever, such openings are of little value unless some object, i.e. driftwood, log, tussock, etc., is available for the birds to haul-out on. Few such objects are present in this area with the exception of planks placed across some ditches by hunters in the f a l l . When these occur in openings the presence of droppings and preened feathers indicates waterfowl utilization. The borrow-pit bordering the western edge of this area was drag-lined in February of 1973. Removal of the accumulated debris of the ditch bottom and the canopy effect of the ditchbank shrubbery may result in a more con-ducive environment for breeding.waterfowI in the next few years. (c) Nesting Cover: . Due to the denseness of the shrubbery virtuaI Iy no understory, in the form of grasses, herbs, and other desirable, nesting cover, exists along or adjacent to most of the ditchbanks. The denseness of the vegetation of the area as a whole makes the nest selection process (Hochbaum, 1944) dif-ficult at best. Hence, it is unlikely those portions of the area supporting potential nesting cover in the form of grass-shrub communities of any size would receive much usage by nesters. The main dyke forming the western boun-dary of the Dense Wildlands is vegetated with reed canary grass interspersed with blackberry vines and a few elderberry bushes. This is potentially good nesting cover for mallards unless burning In the early spring of 1973, approximately 1000 yards of this dyke was resurfaced with ditch cleanings. Hence no nesting cover remained for the 1973 nesting season and it will probably be several years before natural reseeding provides vegeta-tive cover dense enough for nesting waterfowI. With the possible exception of the dyke, the Dense WiIdIands appears entirely unsuited to supplying the cover needs of cinnamon teal. Similarly, the absence of trees containing natural cavities and of artificial nesting boxes, results in virtually no wood duck presence in this area. • . (d) Food: As in the agricuIturaI areas little can be said quantitatively with, regard to food as a limiting factor in the Dense Wildlands. However, I would be more . I i ke I y to consider this a poss i b.i I i ty . i n this area than elsewhere i n the study area. In summati on, the Dense Wildlands have • Ii ttIe to offer, inthe way of requirements for nesting and' breeding 'waterfowl, particularly cinnamon teal and wood duck. In some places, two and even three of the requirements are present but there are very f ew' •.] nstances in which a I I four appear satisfac-tory. This is reflected, in the very low number of pairs and broods (see Tables VI-3 and 6.) censused in the area. OPEN WILDLANDS (a) Water: This habitat is one of three in the study area in which the water table is not controlled by pumping. There are a variety of water-bodies present including several former tidal channels, a borrow-pit, peat ponds and ditches. All ditches. except the one paralleling Rannie Road have received little maintenance since construction in 1915. Consequently much of their length has become choked and narrowed by natural aquatic and ditchbank succession, windfall, and aging of the ditch (i.e. bank erosion, etc.). Nevertheless, occasional open spots seemingly complement the more overgrown portions, resulting in scattered waterfowl use. The biggest problem with the ditches, other than ones with brushed-in banks, is their narrowness. They average 3{ feet across compared to a 6 foot average in most agricultural ditches. This factor greatly increases predation opportunities. The ditch adjacent to Rannie Road is periodically cleaned and main-tained and is more like ditches found in the farmlands. However, its . depth, especially at the south end, the dark colouration of the water im-parted by suspended organic particles, and the considerable flow created when the flood-gates adjacent to the north end are open all serve to.limit both.submergent and emergent vegetation growth. Consequently, few ducks were observed using this waterway during the breeding season. The borrow-pit is very similar in conformation to that found in Ag. I. Its waters tend to be darkly stained and this may have some effect on aquatic vegetative and i nvertebrate life. The."peat ponds" are largely restricted to the Sweetga!e-Labrador Tea Community (see Appendix I). All but one are natural depressions that contain water the year round, fluctuating in depth at the deepest part from 10 inches to 18 inches. The exception was once a. natural depression that has been dyked for hunting purposes. It averages a few inches deeper than the other ponds. These ponds are in an area undergoing a successional change to.peat bog and aerial photography reveals that during the last twenty years, mat-formation and subsequent colonization by ericaceous plants.and sphagnum has severely encroached on some ponds and has obliterated others. Existing ponds appear to meet the water requirement of breeding waterfowl although their close proximity to each other may limit the number of potential terri-tories available to .territorial species. Three sloughs are present in this habitat area, and together with the ponds, these, account for the bulk of the early season waterfowl presence. 1.73. Gj I ley Slough, in the southern portion of the area, and the largest of the two unnamed sloughs at the northern end retain water of varying depths the year round. In GiI ley Slough, water level trends are often at odds with that found in the. surrounding area. This is due to the beaver dams that continually appear on the borrow-pit, thus backing water up into Gil ley Slough. Breaching of the dams during dyke patrols and maintenance. can result in a drastic drop in the water level of the slough in a matter of hours. The smaI lest.sIough, at the northern tip of the.area, is often re-duced to a trickle during periods of low water in the adjacent ditch and bo-row-2 i f. ; A final type of water body is found adjacent to, and usually at the distal end of, the small side channels emptying into Gil ley Slough. These are low areas which contain standing water up to a maximum of .12 inches in depth for much of the year. Vegetated with tussocks of Carex spp. scattered throughout, these areas offer considerable attraction to ducks, primarily ma I lards and wood ducks. (b) Loafing Sites: Potential loafing sites are more in evidence in this area than those previously discussed. Most of the east-west ditches and the two largest sloughs contain wind-fallen limbs and trunks from adjacent frees, primarily cottonwoods. In addition, periods of low water expose sections of sloping mud and sand between the regular bank edge and the low water mark in GiI ley Slough.' These bars are extensively used by loafing ducks i.n the spring but fluctuating water levels make their availability uncertain much of the time. Tussocks of Carex spp. along the sloughs and in the adjacent wet areas of GiI ley Slough were used on occasion, although subject to possible inundation 174. by fluctuating water levels. The shallowing of the upper reaches of the sloughs by plant succession (see Section 4.3.5) creates mats of vegetation suitable as loafing areas. Similarly, succession in the "peat ponds" results in occasional hummocks of sphagnum forming in and around the ponds and these too can be utilized as loafing sites. Because of .its depth and flow few opportunities for loafing exist.along the ditch adjacent to Rannie Road. The borrow-pit has few large trees adjacent to it and hence there is little in the.way of windfall to supply loafing sites. Beaveridams, or remnants thereof, offer limited opportunities. Sections of, this waterbody contain the narrow strip of Juncus-covered substrate (see Fig. V f-20) formed during dyke.construct ion. This offers some possibilities for loafing sites. In summation, this habitat type offers more potential loafing sites in, and ad-jacent to, most.water-bodies than is available in the farmlands or the Dense Wildlands. However, certain sections of the area, such as the borrow-pit and part of Gil ley Slough, might receive greater waterfowl use were more haul-out sites available. (c) Nesting Cover: In terms of mallard nesting cover the predominance of grass and grass-shrub communities in this area (see Appendix I) appears to ensure no lack of this requirement. With respect to the dyke, and portions of the ditch-banks, this is true. However, some areas of bluejoint and bluejoint-hardhack especially those adjacent to the eastern half of GiI ley Slough usually contain water just below the soi I surface. Examination in.these areas of the duff layer in which a nest bowl would be formed often revealed this to be a sodden mass. To what degree'this would discourage nesting is unknown but should be considered when evaluating the area. Much of the banks of the two smaller sloughs are heavily vegetated by hardhack, as are the more westerly 175. Figure VI-20: Mounds of substrate left in the middle of borrow-pits during construction provide some loafing sites for waterfowl. 176. reaches of Gilley SIough. To what extent the hardhack acts as a barrier-preventing a nest-searching f ema I e f rorrr exp I or i ng the nearby grassy areas i s undetermi ned. . Cinnamon and blue-winged teal were seldom seen in this area throughout the.breeding season and I suspect, that some.aspect of cover interspersion or phenology is the reason. Despite the presence of large tracts of grassy-type communities, there is little similarity in physical appearance between this area and the road allowances and.pastures of Ag. I frequented by teal during their nesting peak. . Although some large cottonwood.s are found in the area, few natural cavities apparently exist and the wood ducks present must depend on nesting boxes for nest sites. In 1972, six boxes were present and, in 1973, five of these remained operational. However, starling use of at least some of these five boxes means that wood ducks would have no more, than-two.or three nest sites available to them. Therefore, considering the relative suita-bility of the other nesting reguirements, I feel that the number of wood ducks utilizing this habitat is, at present,, limited largely by lack of nesting opportunities. Provision of nesting sites in suitable locales should result in increased wood duck productivity in this area (see-Section 6.4.0). (d). Food : The. role of food in attracting and holding breeding pairs to this habitat type, as' in the others previously discussed, is difficult to ascer-tain. Baiting for hunting purposes is carried out in the vicinity of the "peat ponds". However, the bulk of this is consumed during the winter months and any remnants are.unlikely to have much influence in holding poten-tial breeders through to the spring.. 177. STURGEON SLOUGH MARSH AND WILDLANDS (a) Water and Nesting Cover: The.dominant factor in determining the suitability of this habitat type for territory estabIishment and nesting by ground-nesting waterfowl is water. More precisely, it is the interaction between the drastic fluctuations in water level (see Section 4.3.0).and various stages of the ma I Iard breeding cycle that determines the degree,, if any,. of ma I I ard productivity in this area .. The . stages of importance occur during territory .estab'l i shment and the subsequent nest initiation and incubation and can be affected in. the foI Iow i ng ways. If, as in 1972, the peak flood conditions of late winter are main-tained by heavy spring rains, most, if not a l l , of the marsh and wijdlands contain standing water of varying depths into early March. Much of the area then takes on the appearance of a small lake, too deep in many places for dabbling and a I most, devoid of loafing sites. Although some flocks of migrants can be seen stopping over for short periods of time, the lack of nesting cover, loafing sites and ideal feeding conditions apparently does little, to attract the.first of the pre-territoria I pairs usually in evidence by th is t ime. However, with the peak of nest initiation occurring in late.April and ear Iy May in I 972. (see Sect i on 6.2.2) all but the earl i est pa i rs shouId have found reasonably suitable conditions by early April, for the water level dropped rapidly beginning in mid-March. Standing water was soon restricted to the centres of the S^. acutus communities, the channels, and some of the ditches. Though s t i l l scarce, some loafing sites are created when snags, 178. deadheads, and the occasional muskrat house is exposed by the receding waters. Ample nesting. cover becomes available in the rapidly drying grass and grass-shrub communities. In 1973, a comparatively light rainfall in late winter, for example, three inches during February as opposed to 13 inches in the same month in .1972, resulted in the previ ous I y . desc.r i bed low water conditions being created by February 10. A continuing, though sporadic, drop in the water level exposed gently sloping mud bars along many of the channels (Fig. Vi-21). With the appearance of these there was a noticeable increase in the number of ducks using the channels, Many of these birds, prior to flushing, could be seen sleeping and preening on the bars. Though most of these birds were, not apparently migratory flocks, I suspect these bars- would offer a similar attractionto territorial pairs. In any event, by week ending April 7, 1973, the peak of nest initiation in that year, reasonably attractive conditions for territorial occupancy had existed for some.time. Therefore, under the two water regimes encountered in the early spring of 1972 and 1973 inter-ference with pre-nesting mallards was relatively slight. The situation encountered by incubating mallards, however,, is quite different. As can be seen from Fig, YI-22, almost the entire.hatching . period is characterized by rapidly rising water levels. This would suggest that in a given year, a substantial number of nests may be terminated via flooding. The extent to which this•happens, however, is influenced consid-erably by the water levels existing during nest initiation. This stems from the mallard's preference for nesting close to water, relative to other puddle ducks, ..(Keith, 1961). Therefore, if we assume that a nesting'bird makes, use of cover available based on the water level at nest initiation, then a significant increase over that level prior to hatching.may result in nest 179. F i g u r e V I - 2 1 : Exposed s h o r e l i n e i n t h e Sturgeon Slough Marsh c r e a t e d by low w a t e r c o n d i t i o n s i n e a r l y s p r i n g . When p r e s e n t , t h e s e mud f l a t s were e x t e n s i v e l y used by p r e - n u p t i a l . w a t e r f o w I . 1972 3* P E A K M A L L A R D H A T C H 0) 0) CL LU Q WEEKS-ENDING ; J A N * FEB |5 MAR ^ A P R I L \° MAY I ' j U N E V JULY 'If AUG |* S E P T 1^  OCT h NOV | 6 E C '., ' ' .' ' 1 1 ' ' ' 1 " h l i ' . i ' n ' i l , ' ! i' • ' « l i t I t i l • H- I I i l I ' I i n i i . 0-i FIGURE VI-22:-CALCULATED HATCHING PERIOD FOR GROUND-NESTING WATERFOWL IN RELATION TO WATER REGIME IN UPUMPED HABITATS-1972 &1973 CO o 181 ... desfruction by flooding. For example, consider the peaks of nest initiation and hatching for 1973 in Fig. VI-22. This shows that between week ending April 7, (i.e. peak nest initiation) and week ending May 12 (i.e. peak hatching), there was a net increase, in water level of 7.3 inches. Thus, birds selecting a nest site at the former.time would have to be situated far enough back from the water's edge to allow for a 7.3" rise in elevation to avoid flooding before hatching. Birds initiating nesting from mid-April on were faced with an even greater fIuctuation, for between May 2 and May 9, an increase of almost I £ feet was recorded in the marsh, Such nest destruction takes on added significance when it is realized that steadi Iy increasing water levels make the poss i b i I i ty of re-nest i ng in ttii i s hab i tat type a I most nil. Based on the notable increase in broods seen in the summer of 1973, nest destruction by flooding appeared much reduced that occurring in 1972. This would appear partiaI Iy substantiated by the particularly high water levels of the latter year which saw the entire marsh inundated by late June. Regardless of year to year variations in degree of flooding, however, annual nest.success under circumstances that see such dramatic increases in water level in the span of a few days can be considered tenuous at best. Of the ground-nesting species present in the study area, the mallard is. the most common under the present hydric and vegetative conditions. In the two years of the study very few pairs of cinnamon teal were seen in the marsh and only one brood was encountered there. It is possible the physiographic state of the grass and grass-shrub communities in the spring, which features a rank growth of lodged and unlodged bluejoint from the previous year, and little of the new growth apparently favoured by these birds, may partially account for 182. the low numbers sighted. However, the dominant reason can be found by com-paring the period of nest initiation and incubation with the water-level trends during the same period (see-Fig, V t-22). In 1972, the peak.of teal hatching, (see Section 6.2.2) had barely begun before the marsh was inundated by the rapidly rising waters.. In 1973,. lack of sufficient data prevented calculation of specific nesting dates. Nevertheless, a total nesting period extending from May 6 to August I (see.Section 6,2.2) indicates that few if any', tea I would be able to nest successfully before rapidly rising water levels forced them to abandon their nests. In fact,, in years of particul-arly high water, as in 1972, it is unIikeIy1 that either nesting cover.or loafing sites.would be available by the time most teal pairs were attempting territorial establishments. Perhaps the most important aspect of wood, duck presence in the marsh is that their nesting habits enable them to circumvent the factor most limiting to production by ground-nesting species, namely the unstable water regime. As in all habitat types in the study area, the degree of wood, duck nesting in Sturgeon Slough marsh is entirely dependent on the presence of suitable nesting cavities, either natural or ar t i f i c i a l . Prior to 1972, no acceptabIe. artificia I cavities were avai IabIe in the marsh. Thus, nesting opportunities were entire Iy restricted to whatever natural cavities existed in.trees located within, and peripheral to, the marsh. Within the marsh, these are limited to approximately 100 cottonwood trees that have pioneered the slightly higher ground created during construction, of the original drainage ditches. Along the eastern boundary of the marsh, the edge of the U.B.C. Research'Forest provides potential habitat of largely a coniferous nature. It is unlikely that the number of cavities provided by these: two sources permitted anything but a minimal wood duck nesting effort in the marsh. 183. Tn .1972, 18 nesting boxes were known, to have been erected in, or adjacent to, the marsh. The bulk of these were located along the eastern boundary of the marsh and the rest a long .severa I ditches adjacent to that area. AM boxes were attached to trees and, though increasing the nesting opportunity in the immediate locality, did little to exploit the untapped potential of the bulk of the marsh. Preliminary steps to remedy this were undertaken in 173 and are.discussed under "Management Suggestions" (see Section 6.4.0). However, under conditions existing as they .did at the conclusion of the 1972 nesting season, the.suitabi Iity of this habitat for wood duck production was severely limited by lack of nesting sites. (b) Loaf i ng Si tes: Although loafing sites were mentioned during the earlier discussion on water levels, I feel that further qualification is necessary. Consider-ing the size of the area containing standing water under average conditions there is a decided lack of loafing sites. Throughout 4.4.mi les of channel system in the marsh, there are only three partially submerged logs that could serve for such a purpose. In the areas of open water scattered throughout the otherwise dense stands of roundstem bulrush there are vir-tually no 'rat houses, mats of vegetation, etc, that could provide the necessary haul-out sites. Pieces of planking from hunting blinds (see Fig. VI-23), catwalks to the blinds (see.Fig. V1-24) and the blinds them-selves, are heavily used by loafing ducks, as evidenced by droppings and preened feathers. The formation of bars along many of the channels only occurs during periods of very low water. Although these provide many haul-out sites the effect of such low water is to decrease the overalI waterfowl hab i ta't ;ava i lab I e because many parts of the marsh become dry by the time that the low enough to.expose these bars. F i g u r e VI-23: Small p i e c e s of p l a n k i n g used e x t e n s i v e l y as a h a u l - o u t l o c a t i o n by l o a f i n g d u c k s . F i g u r e VI-24: Walkway t o h u n t i n g b l i n d showing heavy use by l o a f i n g and m o u l t i n g w a t e r f o w l . Under normal or high water conditions,.most of the shoreline assoc-iated with the channel system, is apparently unattractive to ducks I feel this reflects the lack of haul-out sites due to the dense vegetation that grows right to the water's edge, thereby . providing few clear areas onto which a duck could climb. Where few such areas do exist any bird utilizing them would be. severely restricting its ability to detect approaching danger due to the height and proximity of the adjacent vegetation. Although water-fowl appear to disIike shore Iines of this type, they wi I I respond quickly to its physical appearance. Keith (1961) noted a marked response in shoreline use following removal of dense cattail stands. This was attri-buted to. the greater access i b i I i ty of shoreline I oafing . spots and the desire of waterfowI for an unobstructed view of the shoreline and adjacent terrain. (c) Food: Finally, the.question of food as a requirement for territory establish-ment is as nebulous in this habitat type as in those already discussed. One would expect there to be an abundance of seeds available when consideration is.given to the extensive acreages of roundstem bulrush, small-fruited' bulrush -and b I ue-jo int. grass in the area.. However, the availability of these and the invertebrate life apparently sought in the- spring, particular-ly by the hen, is an unknown quantity until more detailed food habit studies are carried out in.the area. PUBLIC. SHOOTING MARSH (P.S.M.) (a) Water: Although the water regime of this habitat type also undergoes a similar 186. annual series.of peaks and lows, they are not as pronounced as those occurr-ing in the adjacent Sturgeon Slough Marsh. Nevertheless, the general trend of a steadily increasing water level'during late spring and early summer results in the presence of standing water throughout most of the marsh during that time. Since this would coincide with the nesting season of most species of ground-nesting ducks common to the study area, water fluctuation is apparently a major factor influencing duck production in this habitat. (b) Loaf i ng S i tes: As in most of the habitat types there is a shortage of loafing sites throughout most of the marsh. During the early spring of 1973, receding water levels exposed a large mud bar along the east side of the upper reaches of the main channel. This was used extensiveIy by both dabbling ducks and shorebirds for.severaI weeks until rising waters again negated its value-Other than the occasionaI 'rat house alluded to earlier, and the.even scarcer piece of driftwood, there are virtually no haul-out sites in the marsh proper. This, not surprisingly, leads to some competition for the. few avail-able sites. One example of this involved Great BIue.Herons (Ardea herod ias) very agressively harassing loafing ducks from 'rat houses in the spring of 1972 (Mclvor --personal communications), (c) Nesting Cover: Except for the dykes, a. thin spit of land at the south end, and the ten artificial', nesting islands constructed in 1968, little terrestrial nesting cover exists. As can be.seen from the cover map (see Appendix I) the vegeta-tive nature of the area is almost entirely roundstem bulrush with patches of cattail and sma I I-f rui'ted bulrush occasionally in evidence. Such habitat is much more conducive to over-water nesters, such as the canvasback, coot. (Fullca americana), ruddy duck (Oxyura jamaicensis) and several species of grebes, than to species norma Ily considered terrestrial nesters. However, during the span of the study, no nesting divers were encountered in this marsh.. Several pairs of ruddy duck were s t i l l present in early May of 1973 but were not known to nest. Coots could be heard calling throughout the spring and summer.. Although only, one coot chick was seen during this time it is entirely possible that others were present elsewhere in the marsh. Similar suppositon applies to Pied-billed Grebes (Podilymbus podiceps) of which, one half-grown young with an adult was seen in 1973. Several theories can be advanced as to the lack of a viable diver nesting population. Perhaps the most dominant is that, prior to dyking in 1957, this marsh was severely flooded during the freshet each spring and. therefore, had no history of duck nesting. Thus, the breeding nucleus from which is derived successive generations of females, each imprinted on this area: as its "home" or natal marsh, had never existed. Another possibility is lack of feed. Although utilizing emergent vege-tation for nesting most diving species of waterfowl restrict their feeding activities to the adjacent open water areas. In this marsh, these are. pri-marily . located at the.northern end and examination of them reveals either a complete absence of submerged aquatics or relatively sparse beds of Watermil-foi I (MyriophyI Iium spp.). I would be surprised if these were adequate to support many birds even supposing they were acceptable as food in the first pI ace. A third possibility is the fluctuation in water level that resulted in the southern half of the marsh being essentia Ily devoid of standing water in the spring of 1973. This, of course, would prevent access, by prospective nesters, to most of this area. In addition, any attempting to nest in the northern portion, where water of varying depths remained, faced the prospect of being flooded out by increasing water depth in May and June. Coots apparently avoid such a fate by utilizing the very few 'rat houses in the marsh as nest sites or by. continuaI Iy building up their nest platform. . . In th i s ve i n it i s a I so worthwh iIe to noto that any substanti a I build-up in the breeding coot population could be a further deterrent to future diver or dabbler nesting effort. This stems from the coot's extreme intol-erance of almost any other vertebrate during the breeding season (Gull ion, 1954). In addition, Ryder (1-961) found that coots compete with diving ducks for nesting foundations and, especially late in season,'commandeer'diving duck nests for.brood platforms-. As far as the mallard and teal are concerned, some nesting undoubtedly occurs along the dykes and perhaps on the islands and the southern spit. Several pairs of cin.nnamon teal were noted just north of the islands during the spring of each year. Later, several single drakes of this species were seen in the same area. In 1972, during a nest search of the southern-spit, a Cl. lib mallard was captured by the retriever used in this search. This, of course, is only circumstantial evidence that the bird was born in this marsh. However, the/possibility does exist. In the areas mentioned, there is abundant nesting cover and only a remote possibility of flooding occurring on some of the islands or portions of the south spit. The status of wood.ducks in this habitat type is much the same as that in' the Sturgeon Slough Marsh. The eastern boundary of the marsh abuts the U.B.C. Research Forest thereby providing some potential, for natural cavities in some of the large conifers located there. The southwest dyke, which separates this marsh from the .Sturgeon Slough Marsh, has a number of.cottonwoods along it in which the occasional cavity may be located. Other than 189. these sites, no other opportunities existed for wood duck nesting in this area prior to 1972. In June, 1972, a brood of 10 downy wood ducks were seen adjacent to the a r t i f i c i a l islands (Gates, 1972). Nevertheless, .1 . feel that the absence of nesting cavities is the dominant factor limiting a much greater use of this marsh by breeding wood ducks. (d) Food: I think the question of food as a prerequisite to territory establish-ment in this area should receive close attention in any scheme to improve production in this area. One would expect that there is a vast supply of bulrush seeds in this area and subsequent investigation may prove this correct. However, cursory examination has revealed a very few seeds per seed head compared to the numbers produced by the same species in the Fraser marshes. .As previously mentioned, the lack of submerged aquatics in many parts of the marsh precludes a very substantial contribution from th i s source. . 6.3.2 Suitability of Habitat Types for Brood Rearing As in the case of breeding pairs, broods of waterfowl require that a given habitat have certain components before it can'be safely utilized. These include food, water, cover and loafing sites which appear, at first glance, to be similar to pair requirements.. There are, however, distinct differences. The food, at least for the first two weeks of a duckling's life, is heavily weighted to invertebrate I ife with fIora.becoming increas-ingly important as the bird matures (Keith, 1961; Sugden, 1973). .Waterbod.ies should have reasonably stable water regimes because of the relationship of food and.cover. Loafing sites that are surrounded by water, such as tussocks 190. of' vegetation, 'rat houses and logs, and are adjacent to cover are . seemingly preferred oyer sites on or adjoining the shoreline. However., perhaps the.most, significant requirement of brood habitat is the necessity . for protective cover. This not only provides the brood's first line of defence against predation but also functions, in many instances, in supply-ing large quantities of invertebrate foods. When necessary, broods wi I I traveI considerabIe distances via land and water, to utilize suitable brood habitat (Duebbert, 1969; Gates, 1965). Some instances of broods travelling up to one mile to habitat newly created by flood waters have been documented in this study, as have numer-ous shorter sojourns. Subsequently,, natural or artificial changes in environmental conditions, such as recession of flood waters or destruction of littoral zone vegetation via drag-Iinging, invoked a marked response in brood behaviour (see Section 6.2.4). Similar responses have been noted by other investigators (Berg, 1956; Keith, 1961). Thus, it is important to consider.the brood habitat opportunities as they exist in the various habitat types of the study area and in the light of known brood distribution and movements. AG. I ' Except for a short portion adjacent to the South Alouette Bridge, the• borrow-pit associated with this habitat type is too deep to support emergent vegetation. Hence, the bulk of the water surface is devoid of cover. How-ever, over the years terrestrial vegetation.a Iong'the-banks, largely black-berry vines and grass spp., have overhung to the water surface. This, plus ditchbank erosion, has completely enclosed a strip of water, varying in width from one to three feet along much of the farm side of the borrow-pit. 191 . Almost invariably, broods surprised on the open water would immediately swim or scurry through the curtain of vegetation, and into the enclosed "tunnel", thereby becoming completely hidden from view. Less frequen-tly, ducklings would swim to the. dyke-side of the pit. However, because of the angle of the dyke, little overhang of terrestrial vegetation occurs. When present, the "tunnel" created is greatly reduced in width. Under these circumstances, ducklings will usually leave the water and hide in the rank growths of reed canary grass and blackberry vi-nes blanketing much of the dyke. Though this maneuver may be effective against avian predators,. it can be very costly for, now that the ducklings are out of their aquatic element, all the advantage lies with the terrestrial predator who, if experienced, can search out the young, one by one. The effectiveness with which this can be carried out was amply demonstrated by the number of young ducklings caught in such habitat and circumstances by my retriever. The drainage ditches criss-crossing the agricultural lands vary in their capacity to provide brood cover. Due to ditch maintenance, very few contain any emergent cover. Ditches in actively farmed areas that have not been cleaned recently have tangles of grasses, vines and occasional shrubs down to the average water level mark. However, the angle of the ditchbank is such that little effective overhang is created in most of these ditches. Birds surprised in such circumstances will immediately leave the water and seek refuge in the ditchbank vegetation or adjacent hayfield, if available. As previously mentioned, such activity can leave the birds quite vulnerable to subsequent predation by terrestrial predators. Newly cleaned ditches have most of the adjacent bank vegetation removed during the cleaning .process and therefore provide little in the way of cover (see Fig. V I — 25). However, ditches flowing through undeveloped portions of 192. 193. this habitat type provide fairly good refuge in the form of an overhead canopy consisting largely of hardhack and willow growing along the banks. Perhaps the most typical of ideal brood cover within this habitat type was that found in Midden Slough during the freshet of 1972, A com-bination of seepage through the dykes and several days of heavy rainfall served to substantia I Iy increase the water I eve I of the ditches and borrow-pits. The latter back-flowed into the slough and flooded a band of Carex spp. and Juncus balticus, approximately 200 feet long and 60 feet wide, along the north bank of the slough. This situation was immediately exploited by; broods in the area (see Section 6,2.4) and continued to be until the water, level dropped, thus eIiminating the cover as such. This was followed by an immediate dispersal of broods to more suitable areas nearby. In 1973, a freshet of lesser volume and an accompanying period of normal rainfall resulted in reduced levels in the ditches and.borrow-pits. Under these cir-' cumstances no brood cover over and above that normally present in the slough was created. Similarly, no concentration of broods was recorded during the 1973 brood season. Perhaps the most dramatic example of brood response to sudden creation of preferred habitat is that occurring in the adjacent North Alouette River during the freshet period (see Section 6.2.4). Though present for only a relatively short period of time, this area clearly demon-strates the appeal that good brood habitat has to ducklings and undoubtedly contributes to. the relatively high productivity of the adjacent Ag. I hab itat type. AG. II - ' As. in the previously discussed habitat type virtually none of the 194. drainage ditches in the developed portion of this area support emergent vegetation due to ditch maintenance. One length of ditch, 400 yards long, is heavily brushed in by willows growing along its banks but other than that, cover within or over these ditches is for the most part lacking. Along some, grass of sufficient, length persists to permit broods to find some shelter if they chose to leave the water. However, persistent grazing by dairy cows along the top and, in many cases, part way down the bank, generally limits such cover to a relatively thin band. The several ditches in the rough pasture are brushed in by shrubs, vines, and willows along the top of the bank. However, for the most part/ these ditches are too narrow and steep-sided to warrant much use by broods. The ditch bordering the base of the U.B.C. Research Forest has some emergent growth but is much too narrow and shaI Iow throughout much of its length to deter most mammalian predators, Wilson's Slough has been drag-lined repeatedly over the years and appears too deep and murky to support any noticeable emergent growth. In addition, the'standard.practice-of 'dumping the cleanings in what was a narrow but useable littoral zone..has, over the years, eliminated any brood cover this, area contained. Pastures line both banks of the slough and heavy grazing has eliminated any bankside vegetation that might normally exist (see Fig. Vl-16). An exception to this is approximately 50 yards of slough at the northern end. Here, and especially on the west bank, a-slight slope into the slough from the adjoining pasture contains a rank growth of grass spp. that, during the height of the freshet, will flood to varying degrees. The latter depends on. the amount of rainfall during the time that high water in the Pitt River backs into Sturgeon Slough and prevents operation of the pumps. Even when the water has dropped somewhat lodging of the grasses Into 195. the slough provide some cover. exception, this was the only stretch of Wilson. Slough on which broods were seen during the two years of the study. The remaining waterbody in.this habitat type, Sturgeon Slough, had, under certain conditions and prior to 1973, the potential to provide con-siderable brood cover varying from good to excellent in quality. On the west bank, at the north end of the slough, a dense stand of cattai I approx-imately 200 yards long and covering-.a total area of just over 3.0 acres separates the slough from the adjacent pastures. Various portions of this stand periodically flood, providing a ready source of cover to broods feeding in the adjacent smartweed beds (see Fig. V I -26). In addition, clumps of cattail torn free from the substrate by the fluctuations in water level, provide ideal loafing sites for broods when they lodge against the outer edge of the stand. The rest of the west bank has little emergent growth but does feature a slight slope from the adjacent fields to the water. This area, averaging approximately 10 feet in width, has been permitted to grow., into a tangie of grass spp. and rush spp. that provide good cover for broods should they elect to leave the water to seek, she I ter.' Such cover, is, of course, some-what risky when mamma Iian predators.are involved. Both types of cover pre-vious I y descr i bed s t i l l existed in the described form at the cone I usion of the study. Prior to 1951 this portion of Sturgeon Slough covered approximately 26.0 surface acres. However, for much of this length there was little in the way of littoral zone or aquatic emergents. The exception was the southern third which was very densely vegetated by emergents, primarily PoIyqonum spp. Creation of the aforementioned littoral zone apparently resulted from channel-ization of the slough during reclamation. Fill obtained during this process was apparently dumped adjacent to the east shore, shallowing that portion.of 196. Figure V1-26: Dense beds of smartweed in section of Sturgeon Slough. Prior to reclamation, many sloughs were vegetated in this manner. the slough and: permitting establishment of emergents. Continuing maintenance of . the' d itch, and the subsequent dumping of f i l l had,, by 1972, resulted in the open water surface of the slough being reduced to approximately 4.5 acres. Conversely, over 20 acres of seasonally flooded littoral zone had been created. Consisting mainly of Carex and J uncus spp. interspersed by small mounds of f i l l that had vegetated to blackberry and grass spp. (see Fig. VI-27), this area apparently provided excellent brood cover whenever water levels were sufficient to flood it. Such was the case during a five day period in June,. 1972. Almost all broods censused in the Ag. II habitat'type during this time were found-in this flooded cover. In addition, a 50 yard length of this cover that also supported a dense grove of SaI i x spp. was extensively used by a flock of approximately 60 pre-moulting mallards. However, a similar survey ten . days later, at which point the waters had receded., thereby eliminating standing water from much of the area, revealed a noticeable decrease in the number of broods using the slough (see Section 6.4.2). Thus it appeared that m°st of the broods using this habitat type utilized this cover for as long as flood waters permitted access to i t . In.January, 1973, the slough was aga i n drag-I i ned and the f i M once more dumped along the'bank. This latest addition to .'s imi I ar .operations in the past has, in many places, either obi iterated brood habitat or created a small dyke along the slough bank that makes flooding of the former I ittoraI zone much less likely than in the past.. A combination of the aforementioned cleaning and lower peak water levels in 1973 resulted -in very little fIooding of the area under discussion and a concomittant decrease in brood use of the slough in general. In summing the status, of brood habitat in this area, it would appear that continuing alienation of the remnants of this habitat, in conjunction, wi 198. Figure VI-27: Flooded cover adjacent to Sturgeon Slough used extensively by broods - June, 1972. 199. lack of nesting cover and loafing sites (see Section 6.3.1), contributes to the relatively low waterfowl productivity observed in this habitat type. DENSE -W I LP LANDS Discussion of the status of brood-rearing areas in this habitat type, based on observed brood movements or distribution, was not possible due to the very.low waterfowl utilization of this area. However, some subjective observations can be made, based on the known requirements of brood-rearing areas. Almost all of the ditches with the exception of the main north-south ditch are heavily brushed in and maintain a canopy of shrubs over much of their length. Though this, offers protection from avaian predators,, it also prevents establishment of herbs and grasses along the ditchbanks and emer-gent vegetation in the ditch proper (see Section 6.3.1). Simi Ian Iy, I ittIe cover is available, at present, along the newly drag-Iined'borrow-pit that borders the west side of this habitat type. Perhaps the only- waterbody that comes close to providing at least some area useful to broods, is the main north-south ditch. Although too deep to support emergent aquatics, heavy shrub growth along the banks, particularly on the west side, overhangs to the water's surface thereby creating a "tunnel", of similar conformation as described in Ag. I. Should ducklings decide to leave the water to seek shelter, a dense tangle of reed canary grass is present immediately west of the shrubs and, in absence of the latter, continues to the water's edge. Somewhat lesser opportunities exist on the east bank, due in part to the more extensive growth of hardhack. In considering this habitat type as a whole, it offer's, little in the way of acceptable brood rearing habitat, a' fact supported by the results of the brood counts. 200. OPEN-WILDLANDS Of the. four areas that, due to hydric and vegetational characteristics are not classified as marsh, this habitat type has by far the most attractive and largest amount, of brood rearing area. As described previously (see Section 6.4.2), many of.the ditches in the area have been shallowed and narrowed by 60 years of natural aging and plant succession. However, few are. completely closed in for their entire length and many yards of ditch are available for brood use. With old limbs and snags providing ideal loafing sites, dense growths of submergent vegetation in which to feed and clumps of Ledum, Spirea and grasses along and, in some cases, overhanging to the water, providing cover, the most apparent' drawback to these sites is their narrowness. The peat ponds are generally fringed with Carex spp., buckbean and Juncus spp. However, the emergent cover provided by these is, in the main, re I ativeIy • sparse and provides limited concealment. The uplands surrounding these ponds are densely vegetated by Labrador Tea, Bog Laurel and Sweetgale. If sufficiently harrassed, broods could obtain some shelter from this source, particularly from avian predators. The pond that has been'.impounded for hunting purposes provides very adequate cover along the dyke banks but this pond is apparently seldom used by broods.. As an overall' impression, I feel that, all other factors being adequate, lack of emergent growth would prob-ably limit brood use of these ponds in the event of greater nesting effort in the. immediate area. The borrow-pit on the western boundary of this habitat type has much the.same characteristics of the pit in Ag. I, and hence provides the same type of brood-rearing opportunities. In particular, the growth habit of. 201 . Sweetgale that sees it extend out from the bank and down to the water's sur-face creates a "tunnel" identical to the type heavily utilized by broods in Ag. I. Similarly, ducklings. couId, under duress, utiIize the terrestrial cover adjacent to both banks of the pit.. In particular, the tangle of grass spp., blackberry vines and young alder that line,much of the would appear well suited for this purpose. Gil ley Slough, and in particular the associated wet areas (see Section 6.3.1), provides excellent brood habitat. From the dog-leg adjacent to Gil ley Slough Road, west to the borrow-pit the bulk of the cover is in the form of several long strips of Carex spp. that flood during the high water of summer each year. Snags and limbs provide fairly numerous loafing oppor-tunities, particularly at the far west end. From the dog-1 eg east the slough becomes ; progress i ve I y 'sha I lower and. in the upper reaches, the. water surface is interlaced with Polygonum spp., Marsh Cinquefoil and other mat-forming species. At this point the shores of the s. hough become increasingly- I ess defined and gradually becomes a swampy area interspersed by clumps of Carex spp., and patches of bluejoint. This appears to be.very attractive habitat, and usual.-1.y contained broods when checked. However, perhaps the best areas of.all were, the flooded areas at the. ends of most the side channels. The. interspersion of.tussocks of Carex spp., and open water appears ideal in offering maximum cover, food and loafing opportunities, yet is not so rank as to impede the duckling's progess. These areas are, of course, at maxi-mum size during mid-summer, due to the freshet, and thus provide a.consider-able amount of cover at a time when the number of broods present is at a. peak. Of the two sloughs at the north end of the habitat type, the smaller one offers some brood rearing opportunities when the extensive growth of 202. Carex spp. fIanking the relatively narrow channel of open water becomes inundated during the freshet. Due to the stage of succession, little open water exists in this stand, which results in a uniform mat of vegetation which offers excellent cover but is less desirable from the standpoint of travelling, feeding and loafing. . Consequently, broods were usually first observed feeding in the open water of the channel, utilizing the adjacent cover only when they become aware of the observer. This slough is also lacking, in haul-out sites and creation of a number of loafing sites would undoubtedly make the area more acceptable. The final area to be considered is the slough just to the south of the one previously discussed. In conjunction with the easterly portion of Gil ley Slough and its adjacent water areas, this slough, provides the most attractive' brood habitat in the Open Wildlands and broods were always observed on it during the counts.- Throughout most of its length the slough is flanked by ; a strip of Carex spp. of varying widths, primarily along the east bank. This, in slightly higher spots, gives small stands of bluejoint and the. combination of the two, when flooded in mid-summer, provides excellent brood habitat. Scattered along its length, mats of cattail or Carex spp. have formed in the slough proper, providing both cover and.loafing sites. The latter are also often present where snags and limbs from long-dead trees protrude from the bank or the water's surface. The open water itself is densely vegetated by submergent and fI oating-Ieaf aquatics which provide a ready source of feed adjacent to the cover and loafing sites. At its distal end, the slough becomes increasingly narrow and shallow. Hence, the bulk of.the broods were encountered in the proximal two-thirds of the slough. As with the other sloughs in this habitat type, the greatest area available to broods is during periods of high water which floods the adjacent semi-terrestrial seres of Carex spp. and bluejoint. 203. STURGEON SLOUGH MARSH AND WILDLANDS •'• In.terms of water, cover and feed, this habitat type provides a con-siderable acreage of excellent brood habitat for most of the brood season. Its most obvious drawbacks are a noticeable lack of loafings sites and,.-towards the latter part of the summer, unavai labi I ity of some habitat due to low water levels. The core of the brood habitat are the S_. acutus com-munities. The dense stands provide the necessary cover and yet there is sufficient open water scattered in and about the stands to provide the shoreline effect so attractive to broods. ln addition, many of these open areas support dense beds of Marsh-Purslane interspersed with clumps of Carex spp., Yellow Waterlily, Smartweeds and Marsh Cinquefoil. These provide both additional cover and an excellent food source of invertebrates. Communities, in which S_. microcarpus is the dominant or co-dominant species require a fairly high water level, in the marsh for these to be available for brood use. When such conditions exist, I suspect cover is the major.benefit derived, for "the build-up of old vegetative material is such that few submergents exist in these communities and little invertebrate life is thus apparent. The most ephemera.I of brood habitats in the marsh are the. grass and grass-shrub communities. This reflects their occupancy of the higher reaches of the marsh Which undergo flooding only during the peak of high water, and then often for only a relatively short period of time. By the end of the first week of August, standing water is often restricted to the centres of the S.acutus communities, the various channels that meander through the marsh, and some of the ditches. At this time, increasing use of the channels becomes apparent. These contain little in'the way of emergent cover but are a source of water and food.. Should danger threaten in such circumstances, ducklings will invariably proceed to the nearest shoreline and seek shelter in the 204. overhanging shrubs, grass or reeds. If pressed further, they will then leave the water and hide in the adjacent terrestrial cover. A number of young wood ducks and ma.! lards'were captured for banding purposes by taking advantage of the latter trait and using a retriever, to search them out in the dense cover. Although many of the ditches are either too narrow or have been shallowed by natural aging, several' of the larger ones provide very- attractive .'habitat for broods. In particular, accumulation of limbs and dead snags in and across the ditches provides a choice of loafing sites seldom encountered . elsewhere in the marsh. As most of these ditches are choked with submergent aquatics, an adequate supply of invertebrates is presupposed. Cover may be available in the occasional mat of emergent growth in the ditch proper or in the adjacent terrestrial or emergent growths. In retrospect, though improvements could be made in the quality of brood-rearing habitat in this marsh, it would appear that it could support many more broods than are presently reared within its confines. PUBLIC SHOOTING MARSH (P.S.M.) This marsh appears to have many of the attributes necessary for good brood-rearing habitat. The dense stands of S_. acutus that occupy the bulk of the area provide excellent cover. In addition, theless pronounced fluctuations in water level, compared to the Sturgeon Slough Marsh, results, in the bulk of the cover being accessible to broods throughout the summer. Adjacent to the dyke in the southern reaches of the marsh, removal of mater-ial during dyke construction has created several small ponds, and a segment of ditch severa I ''hundred yards ...long. Surrounded by alders'and willows and containing some stands of emergents scattered among dense patches of sub-mergents, .these areas appear very attractive to broods. Windfall from . . . 205. adjacent trees.has created a few loafing sites that further complement the area ' s appea I . . . . . However,. severaI conditions exist that may restrict optimal utiliza-tion of this marsh by broods. One of these is the almost total lack of open water areas within the bulrush stands. This results in relatively 'I ittle shoreline and thus reduces the amount of edge available to broods. The shading effect of the bulrush limits the growth of submergent aquatics and in this manner may reduce the number of invertebrates available to ducklings. A Iimited number of inverfebrate.samples taken in the marsh have shown that it supports the lowest yield per surface-acre of the six habitat types in the study area (see Section 5.2.1). Several causes of th.i s were subsequently suggested (see Section 5.3.1). However, further study would be necessary to definitely establish that food could limit brood survival in this marsh. Another consideration is the almost total lack of loafing sites in the marsh proper, a factor that also detracts from the area's suitabi Iity for territory establishment (see Section 6.3.1). Despite these drawbacks, I feel that, assuming food is not limiting, the Public Shooting Marsh is capable of maintaining a sizeable brood population, particuIarIy if management tech-niques to.a IIeviate the shortage of loafing sites are implemented. 6.3.3 Effect of Predation. on Waterfowl Productivity Few investigations of waterfowl' nesting productivity can be summarized without discussion of the impact of- predation on some, or a l l , segments of the waterfowl reproductive cycle. Though this runs the gamut from early pair formation in the spring to attainment of flight by the last of the juveniles in late summer, by far the most attention has been centred on the loss of nests and downy young. . In fact, few nesting' stud i es- have failed- to 206. show that predation was responsible for.the bulk of nest loss (Keith, 1961). During his work in South-eastern Alberta, Keith found that predation accounted for the fate of 53$ of 417 nests located in an unfenced area of.prairie. Striped Skunk (Mephitis mephitis) and coyote were primarily responsible for this loss. In conditions more typical of the current study area, Wheeler (1966) attributed 24.3$ of nest failure to mammalian and avaian predation during his study of duck production on reclaimed farmland in the Humboldt Bay area' of CaIifornia. Similarly, in a seven square mile area of Wisconsin, in which 71$ of the land area was cultivated, and dairying a major farm enter-prise, striped skunks and raccoons accounted for 80$ of nest failures of mallards and blue-winged teal under conditions which saw only 30$ of all nests successful (Gates, 1965). For reasons discussed earlier (see Section 6.2.2) only nine active duck nests (see Table V1 -4) were found during the two field seasons.combined. Hence, the extent of predation on the local duck population of the study area has to be based largely on-qua Iitative-evidence based on predator sightings, (Table VI-9), suspected predator kills and actual instances of predation (Table VI-8) rather than the more commonly used nesting data. (a) Mammalian Predation: During the two field seasons, a total of twelve sightings of mammalian predators were made, four of these in 1972 and eight in 1973. Of the species of predators sighted, several have been documented in other studies as being particularly efficient in preying on. waterfowI. Weasels (Mustela erminea), of which three were sighted in the study area, were reported .by Hansen (1947) to have accounted for 9.5$ of the waterfowl nest destruction in his study area. In the Ruthven area of Iowa., weasels destroyed four blue-winged tea I nests 207. (GJover, 1956) while in south-east Alberta, approximately 3$ of nesting hens were killed by this tiny predator (Keith, 1961). Raccoons have been noted as a. principal predator on breeding waterfowl, their nests and young wherever the distribution of these creatures overlaps (Glover, .1956; Earl, 1950; Wheeler, 1966;.Gates, .1965; et aj_.). Two instances of predation actuaI Iy occurring were documented, both involving mink (Mustela vision). Significantly, this' animal has a particul-arly ruthless reputation as a killer of waterfowl. At Red Rock Lake, in south-central Montana, a combination of high brood density and a nearby-mink den resulted in a situation where "dead ducks littered the holes and trails..." and ''the bodies of old birds and ducklings of two to six weeks-were everywhere, partly eaten or left intact..." (Errington, 1964). Simil-arly, mink accounted for 14$ of destroyed nests in Iowa (Glover, 1956). As a result of several experiments involving mink-waterfowl interaction in North Dakota,' it was suggested that, due to their predatory traits, semi-aquatic environment and wide-spread distribution, mink may be a major cause of mortality on waterfowl in some areas (Sargeant, Swanson and Doty, 1972). The impact of coyotes as a predator in the Pitt area is somewhat in question due to the apparent yearly variation in their numbers. For instance, no sightings of coyotes were made throughout the 1972 field season whereas . four different sightings were made in 1972. These were in addition to num-erous unconfirmed' reports by local residents of coyote sightings, including one family of five animals seen on two different occasions on the Harold Haywood property. According to the local trappers, coyotes only move down, from the mountains to the west, and east of the study area during, periods of heavy snow in the winter Hence,, whether the apparently large number present as spring and summer residents in 1973 is atypical can only be ascertained 208. by further study. Nevertheless, when present, the coyote can be considered a predator of breeding waterfowl (Keith, 1961). Perhaps the most surprising instances of predation encountered by the writer involved the discovery of duck remains in 5 of 9 River Otter scats collected and examined in 1972. Casual field examination of scats in 1973 failed to reveal any containing -duck remains although several containing Red-winged. Blackbirds (Agelaius phoeniceus) were found, as was the case with most of the nine examined the previous year. In fresh water habitats, the food of otters consists mainly of fishes although birds and mammals are taken, occasionaIly (Cowan and Guiget, 1965). In their study of otter food habits in the Great Lakes region, Knudsen and Hale (1968), upon examination of 2,025 gastro-intestinaI tracts and 184 scats over an 8-year period, deter-mined fishes were, the main prey species with crayfish, frogs and aquatic, insects of some importance. Duck remains occurred rarely in scats. However, it is important to note that only the scats were collected at a I I seasons of the year. The stomachs and intestines were obtained almost entirely from otter trapped in late winter and early spring, at which time virtually no broods of waterfowl would be present in that region. (b) Avian Predation: No. da i ly s i ght i ng I i st of avian predators was kept duri ng the two field seasons. A reliable indication of avian predators present on, or adjacent to, the study area was a census of active raptorial eyries plus observations on crow numbers during the spring and early summer. The results of these ob-servations are noted in an earlier section (see Section 6.2.5). That these birds exert a substantial part of the predation pressure directed towards avian prey species is supported by the instances of possible predation recorded 209. on the study area in 1972 and 1973 (see Table VI — 8). These show that of the eleven occurrences recorded, eight were evaluated as resulting from raptor i nvo l.vement, . one' i nvo I ved a crow and two stemmed from mammalian; predation. The most common raptorial species encountered in the study area was the Red-tailed Hawk. Although generally conceded to be a beneficial species,, due to its propensity to capture many species of rodents considered economical-ly undesirable (Bent, 1937; Gabrielson and.Jewett, 1940), this large buteo has been known to prey on waterfowl. A recent example is the investigation of the habits.of nestling and fIedgIing Red-taiIs near Rochester, Alberta. Conducted over a four-year period, this study revealed that ducks and duck-lings constituted 12.2$ of the prey biomass and 7.0$ of the prey occurrence brought to the nest area by the adult birds. Unfortunately, it did. not . prove feasible to examine any Red-tail eyries for regurgitated pellets or prey remains on my study area. Hence, the impact of the Red-tail as a waterfowl predator is s t i l l open to conjecture. Although sightings of Marsh Hawks were made throughout the. late spring and summer, these occurred infrequently enough to suggest that the resident population is relatively small in number. However, this Iimited presence . should not be entirely discounted for simiIar studies have, shown this hawk to prey on waterfowl more often than is commonly thought (see Fig. VI-28). .Mendall (1958) observed Marsh Hawks actually killing adult ring-necked, ducks and attributed four of sixteen known predation losses among adult females to this raptor. In North Dakota, an adult femaIe Marsh Hawk was observed capturing and kill i n g a fledged baldpate, albeit with some difficulty (Hammond, 1943). On the Fraser Delta marshes, marsh hawks have been seen attacking hen mallards with young on several occasions (Tener, 1948). As with the.Red-tail.nests,, we were unable to climb to either the-210 Figure V I—28: Female femaIe Cinnamon Teal being marsh hawk - Apri I, fed on 1973. by 211 .. Osprey (Pandion ha I i aetus) or Bald Eagle eyries located on or.adjacent to..' the study area. Hence, little quantitative or qualitative evidence as to local food habits of these species is known. On numerous occasions, Ospreys were seen either fishing or in the process of carrying a fish, usually Carp,, to their eyries. This raptor is believed to feed almost exclusively on fish (Bent, .1937) and only one. recorded instance of predation on water-fowl was found in the Iiterature (Kuser, 1929). It is unlikely that the Osprey can be considered a major predator of. waterfowl in the Pitt area. According to Bent (1937), the bulk of the food of the Bald Eagle con-sists of fish although when thPs source is scarce, ducks and geese are util-ized, along with many other species of birds and mammals. On two occasions, . one of the pair of eagIes.nesting on the study area was seen flying to the eyrie with a large fish, probably a Carp, in its talons. These birds were seldom seen hunting about the study area and, as.with Osprey, it is doubtful if they exerted much predatory pressure, on locally nesting ducks. The only other avian predator of note present on the study area was the Crow. These birds were sighted most frequently in the agricuIturaI section of the study area.and flocks varying in size from 10 to 30 birds could be seen foraging in the pastures throughout the spring and early summer. Con-siderably larger flocks are present in the late summer and early spring.. Few nests were found and those located were largely confined to the agri-cultural areas. This noticeable preference for the farmlands by crows probably reflects the greater availability of feed in this area. In the spring, most farmers spread manure on their pastures and crows soon congregate at these locations where they can be seen sifting through the straw and dung. By mid-May, the first of up to five cuts of silage is taken off the fields, followed by haying in June, and crows are particularly attracted to these 212. sites, presumably at the prospect of picking up .small rodents, insects and ground-nesting birds incapacitated by the mowers. Occasional forays are made into the marshes in the spring where-crows.couId be seen avidly feeding on frogs stranded by the very low waters in the marsh at this time of year. Although, one sighting of a crow carrying what may have been a duck egg was made (see Table V I-8), another experience leads one to ponder as to the role that waterfowl play in the prey base of crows in this area. This involved an incompl ete ma I Iard's nest containing three eggs that was deserted, after the hen was hit by a cutter bar during mowing operations. The eggs lay in plain view in an area frequented by crows, and in fact, was located only 100 yards away from an active crow's nest. Even so> exactly one full month elapsed before this nest was destroyed by an unknown predator. (c) Distribution of Predatory Pressure: Due to the appraoch- in assessing the impact of predation on the study area, it was not possible to qualitatively delineate the distribution of predators, according to the various habitat types. Although seven of eleven instances of possible predation (see Table VI-8) and seven of thirteen sightings of potential predators were in the agricultural areas this does not necessarily indicate a greater density of predators here "than elsewhere in the valley. This may stem from the far greater likelihood of seeing predators and/or remains of possible predator kills in the relatively open terrain of the farmlands, as opposed to undeveloped areas. However, there are indications that predators may favour habitats in which cover interspersion is such that much of the foraging can be done in relatively open areas or, when in heavier cover, along "travel-lanes" such as fence rows, ditchbanks, cow-paths, deer trai Is, dykes, etc. 213. Earl (1950), i nvest i gat i ng ma I I ard productivity i n the Sacramento Valley-, found that over half the nests located along roadsides and ditches were destroyed by predators. A. similar study in the Rainwater Basin Area of Nebraska showed that all nests initiated in fence rows were destroyed by predators (Evans and Wolfe, 1967). In the farmlands, ditchbanks, dykes and roadsides were apparently favoured as nest sites, for six of nine nests were found in this cover type (see Table VI-4). As in the aforementioned studies, these areas were well utilized by predators. Fox, coyote, and, particularly: raccoon tracks could often be found paralleling the ditches that border most of the crop fields. Due to the much denser cover types in.the wildlands and marshes, tracks of potential predators were far less obvious. Nevertheless, any drop in water level, that permitted mud bars to show along the edge of large ditches or sloughs soon provided evidence of predatory animals in these areas, predominantly raccoons. Deer runs, and trails created by hunters, that.were adjacent to ditches or s loughs were often heaviIy tracked, by raccoons. Although only one active nest was found destroyed by predators in the study area, it seems the probability of such encounters is considerably heightened by the apparent preference of ditchbanks as nest sites and the semi-aquatic foraging habits of several of the more common predators, partic-ularly the mink and. raccoon. Keith (1961) noted that predation rate was apparently unrelated to nest density and nest concealment in certain parts of his study area and suggested this may reflect the foraging habits of the main predators. It may also be that the predation rate in the wildlands and the marshes may be lower than that encountered in the agricultural areas. This could result from the far denser cover found in the former areas.. In particular, the dense stands of bluejoint make travel throughout these areas 214. difficult. . Duebbert (.1969) attributed the low predator activity on retired cropland in South Dakota to the height and density of the vegetation. He felt that the tangle of dead grass and weed stalks present in the spring deterred predator activity and minimized horizontal movement of,air currents that would attract predators. Support for this premise is offered by Kirsch (1969) who placed dust plots in the vehicle tracts of a cab Ie-dragger used to find duck nests and in adjacent ungrazed areas without vehicle tracks. These plots reveaIed fox tracks in 43$ of 56 exposures located in vehicle trials as opposed to only 8% occurrence in 60 exposures situated in denser cover. Hence it i.s suggested that ease of travel, preponderance of arti f icia I and natural "travel-lanes" and a probabIe greater abundance of the overall prey base in the agricultural areas may result in greater predator activity in these areas. As this study has shown that these areas also support the greatest nesting density of waterfowl then predator impact on the waterfowl resource can be.expected to be greatest in these areas. . 6.3.4 Productivity of Local Waterfowl Despite the intensity of the "comparative" brood surveys (see Section 6.1.3) it was apparent that only a portion of the broods were being censused. This was due, in no small part, to the generally furtive response of broods to the presence of an observer. Conversely, territorial pairs are far more obvious in their response to an intruder. Thus, a greater proportion of pairs present in an area will be seen as opposed to the broods that wi I I later ori-ginate from these pairs. Therefore, it was felt that the production of young, based on the maximum number of territorial pairs in a given habitat, would more closely approximate the actual production than would the number of young actuaI Iy seen. 215. However, as'stated ear Iier, (see Sect ion 6.2.I) pair counts were not obtained in I972:, thus negating such an approach for that year. In. 1973, the maximum number of pairs in each habitat (see Table Vl-3) was calculated (see Section 6.2.1). However, production studies of waterfowl throughout North America have shown that only a portion of the breeding pairs success-fully.hatch a nest (Kalmbach, 1939). Taking.into account the renesfing rate of various species, Keith (1961)' calculated that 49$ of thepairs.on his study area succeeded in hatching a nest. Application of this percentage to the data shown in Table Vl-3 permits calculation of the number of pairs producing a brood on the six habitat types in 1973 (see Table VI-1'7). The number of flying young produced in various habitat types in the study area (see Tab Ie VI -18) is obtained by multiplying the number of calculated broods for each species (see Table VI-7) by the average Class Ml brood size for that species (see Table V1-7). , Although such calculations can be utilized where "complete" census of pairs occurred they are not applicable to the "comparative" pair counts taken in the Sturgeon Slough and Public marshes (see Section 6.1.1). In these habitats, estimates of.product ion reflect a numberof parameters including the "comparative" surveys, results of trapping for banding purposes, and sightings of broods throughout various.aspects of the summer's fieldwork. Based on these I would estimate that, within the 2,554 acres comprising the Sturgeon Slough Marsh and its associated wildlands, the following minimum number of broods were raised in 1973: 12 mallard, 5 blue-winged or cinnamon tea I, "3 green-winged teal and 8 wood duck. Similarly, in the Public Shooting Marsh, the following brood production is estimated for 1973: 4 mallard,. 3 blue-winged or cinnamon teal and 3 wood duck. The.estimated number of flying young raised in these two habitats in 1973 (see Table VI-19) is ob-tained by multiplying the number of broods of each species by the average 216. Table VI-17: • Ca1cu1ated Hatching a Number Brood -of Breeding Pairs Succes - Pitt Val ley, 1973 sfu 1 1 y Species Ag. West 1 ' East Ag. 1 Open Dense WiId lands WiId lands Sturgeon S1ough Marsh Public Shooting Marsh la Hard 5 3 3 5 1 . 2 1 I.W./Cin. Teal 6 3 . ' 3 • - - • - 2 'ood Duck 5 2 1 3 ' - 1 l.W. Teal- - - - 1 -Table VI-18: Calculated Flying Young Raised in Selected Habitat Areas - Pitt Valley, 1973 Species Ag. West 1 East Ag. . Open , Wildlands Dense . Wi I'd lands Tota 1 Ma 1 lard 25 15 25 . 5 85 B.W./Cin. Teal 36 18 18 - 72 V/ood Duck 25 10 5 15 - 55 G.W. Tea 1 — -' - • - '- ' -' Tota1s 86 43 38 . 4 0 5 . 212 Table VI-19: Estimated Flying Young Raised in Sturgeon SI. Marsh . & Wildlands & the Public Shooting Marsh, Pitt Valley, 1973 Sturgeon Slough Marsh I Wi1dlands Public Shooting. Marsh Total Ma 11ard 60 20 80 B.W./Cin. Teal 30 18 43 Wood Duck 40 15 55 G.W. Teal- , .15 - 15 TotaIs 145 53 198 217. number of young per brood for that species. Thus the production of flying young for the six habitat types in 1973 can be obtained by adding the totals' of Tables VI-I 8 and VI-19. The production for the entire study area can also be calculated. Within the area there are a total of 1,951.5 acres not included in the six habitat types.. Of these, 1,620.3 acres (2.53 square miles)- are of a habitat type similar to Ag. 1,1 whereas the rema i n i ng 331 .2 acres (0.52 square miles) approximate the habitat conditions found in the Dense Wildlands. In 1973, 7.9.5 broods/square mile were raised in Ag. II habitat type and 1.40 broods/ square.mi Ie ' in•Dense Wildlands (see Table VI-20). Thus, the 2.53 square.mi les would have produced 20.broods (2.53 square miles x 7,95 broods/square mi Ie). Similarly, the 0.52 square miles would produce I brood (0.52 square miles x 1.40 broods/square mile). Assuming an average brood size at Class Ml, of 5.2 ducklings for the three main species, then the I95M5 acres raised a total of 109 (21 broods x 5.2 ducklings/brood) duckl ings to the flying stage in 1973. Finally, the estimated total production. of flying young for the study area in 1973 is the sum of the ducklings raised in the six habitats (410) plus those raised on the remainder of Pitt and Alouette Polders (109) for a total of 519 flying young. In terms of broods per unit area, the. 12 square mi les.of Pitt and Alouette Polders produced 8.3 broods/square mile in .1973. Though of definite local management interest in themselves, these production figures are best evaluated in light of duck production emanating from both similar and dissimilar habitats.eIsewhere. Gates (1965) cone Iuded a 5'year study of reclaimed pasture lands in Wisconsin with an average annual production estimateof 4.0 broods per square mi le. At Humboldt Bay, California, former tidal and estuarine marshes that had been converted to pasture I and 218. Table VI -20: Calculated Pair & Brood Productivity in Habitat Areas - Pitt Valley, 1973 Selected Habitat Unit Size (acres) Breedihq Pa i rs Broods Pa'i rs/sq. mi . Broods/sq.mi. Ag.' 1 - west 475.0 31 • 16 42.0 22.0 Ag. T- east 334.0 17 8 31.0 15.0 Ag. 1 Tota1 809.0 48 24 37.5 18.7 Ag. 11 560.4 II. 7 12.5 7.9 . Open Wild land 565. 1 15 8 17.0 9.1 Dense Wi1d1 and 453.7 2 1 2.8 1.4 TOTAL 2944.0 . 76 40 16.5 8.7 Table V I-2 I: Number of Broods Censused in Selected Habitat Areas - Pitt Valley, 1972 & 1973 Number of Broods Habitat Unit Ag.I - west Ag.I - east Ag. II , Open WiIdland Dense Wildland Size (acres') 475.0 334.0 560.4 565. I 453.7 June 18-22, 1973 9 N/A 10 3 June 23-24, 1973 .12 8 6 I TOTAL 23 27 219. produced 21.0 and 15.9 broods/square miIe in 1964 and.-1965 respectively (Wheeler, 1966). In north-central South Dakota, 125 acres of retired crop-land centered in three square miles of intensively utilized farmland pro-duced 19 broods/square mile (Duebbert, 1969). On the Canadian prairies, generally recognized as the backbone of waterfowl production in North America, production figures fluctuate con-siderably, depending on water availability. For instance, in 1952 and 1953, under optimum habitat conditions, the Redvers Waterfowl Study area, in Sask-atchewan produced 50 broods/square mile. By 1962, successive years of drought conditions had reduced this to 2 - 3 broods/square mile (Stoudt, 1962).. Somewhat similar trends occurred on the Lousana Study Area, located in. the aspen park I ands of central Alberta. In that area, between the years 1953 and 1959, production fluctuated from a low of 30.0 broods/square mile, in 1959-to a high of 120.0 broods/square mile in 1958. The seven year average was 71 broods/square mile (Smith, I960). Thus, though far below the production capabilities of the acknowledged duck factories of the prair-ies, the study area, in 1973, appears to be in the general range of produc-tivity experienced in areas of s im i lar. or i g i n ..and land use. As previously mentioned, it was not possible to calculate similar productivity estimates for 1972 because pair counts'were not available. However, some insight into production in 1972 can be gained by comparing the actual brood counts for that year with those taken in the same areas in 1973, (see Table VI-21). From these it would appear that the four habitat types subjected' to "complete" census produced slightly more broods in 1972 than 1973. Assuming the pairrbrood in these habitats was the same in both years then pair counts in 1972, had they been taken, would have indicated propor-tionately more pairs in that year. Thus, application of a similar calculation 220. as was used on the 1973 pair counts would have indicated slightly higher production of . fIying young in these four habitats than the 410 raised in 1973. As in 1973, estimates of production in the 2,554 acre Sturgeon Slough Marsh and'its associated, wi'ldlands and the 582 acre Pub I i c Shoot i ng marsh in. 1972 are somewhat qualitative in nature. However, due to the very high water levels experienced throughout much of this area in the spring of 1972, I would suspect that teal and mallard production .was negligible. Of 16 wood duck boxes in or adjacent to these areas, only 3 were known to have produced broods. Thus, I would state with some' confidence that it is unlikely that these habitats combined contributed more than 50 f I ying young in 1972. Thus, overall production in the entire Pitt and Alouette polders in that year would probably be in the range of 460 - 480 fledged ducklings of .all spec i es. 6.3.5 Use of Marshes by Moulting Adult Waterfowl Perhaps one of the most important periods in the annua I.cycle of. an adult duck's existence is the latter part of the eclipse moult during which the bird is rendered f I ight I ess. for a period of 3 to 4 weeks (for a general discussion of moulting, see Kortright, 1953). As if sensing their vulnerability at this time, the birds seek the seclusion and protection of large, densely vegetated marshes which are not given to sudden and complete loss of water. These provide not only the primary requirements of food and cover but also the isolation that the birds apparently require at this time (Hochbaum, 1944). Because of their importance, waterfowl will make definite seasonal movements to areas providing such, requirements (Hochbaum, 1955). 22|. Such movements, of course, depend.on the species and breeding status of the waterfowl, involved. With respect to puddle ducks, the earliest breeding drakes are the first to moult Iater. breeding drakes and non-breeders, in that order. Unsuccessful nesters often.moult in the latter part of the above sequence. Females with broods generally do not . enter the flightless period until their young are fledged and hence, are the last segment of the adult population to mouIt (Sow Is,I 955). During the 1972 summer field season we. became aware of increasing, evidence that Sturgeon Slough Marsh and probably the Public Shooting Marsh may serve an important function as a moulting marsh. Beginning in late.May, increasing use of. the only prominent loafing spots in Sturgeon Slough Marsh, namely the catwalks to the hunting blinds, was reflected in steady accumula- . tions of droppings and preened body feathers. By June 20, 1972,.the catwalks under observation were a mass of droppings and many moulted primaries and . secondaries. Examination of these feathers revealed a moulting population of mallard and wood duck. No teal feathers were noted at-any time. During this period an increasing number of flocked adult mallards were noted, in the study area. Over 80 were flushed from temporarily flooded cover along Sturgeon Slough at this time, many of which were drakes in various stages of ecIipse pIumage. Most of these birds were observed to fly in the direction of the. marshes upon flushing. On June 21, 1972, four drake mallards well into the eclipse and two hen mallards were seen utilizing a parti a Ily flooded field in Alouette Polder. However, despite these sightings, excursions into the marsh were too infreguent to permit any quantitative assessment of moult-ing waterfowl usage. Such was not the case in 1973, Implementation of a banding program necessitated at. least one, and often two, trips each day into.Sturgeon Slough Marsh during most of June and July. These permited almost daily assessment of the progression of the moulting season and trapped birds gave some ideas as to species and numbers (see Fig. VI-29). In late May, 1973, there was little sign of extensive moulting use of either marsh.. However, by June 2 there'were numerous droppings and preened body feathers in evidence on the catwalks. In addition, sma I I groups of wood ducks, largely consisting of drakes, were being flushed from the marsh adjacent to the. catwaIks. By June 13, the first moulted flight feathers were in evidence. In addition, groups of mallards were also being seen nearby, as well as flocks of wood duck. On this date, trapping commenced and continued almost continuously unti I July 22, 1973.. (a) Moulting Use by Mallard and Wood Ducks: By the end of June, a total of 35 wood duck had been banded of which 26 were adult drakes, 8 were adult hens with no known brood and one was an adult hen with, a brood. Only 2 banded birds were recaptured during this period, both of them drakes. -.The latter event may be taken to indicate that (a1), trapped wood ducks became very wary of traps subsequent to release or (b) there was a large enough population of unhanded wood duck in the immediate area that chance eliminated a large number of-retraps at this time. 1 tend to favour the second postuI at ion for upon approaching the traps, I often flushed large numbers of birds' sitting nearby. For instance, on June. 13, 44 wood duck and I mallard were flushed in this manner. This, of course, does not include the number of flightless or near flightless birds that skulked off upon hearing the approaching boat. ft was on thi s date a I so that flocks of ma I lards.couId be seen at a considerable height flying into the two marshes. On the 18th, two flocks Figure VI-29: Pre-mouIting mallards and wood duck in floating funnel trap - Sturgeon Slough Marsh, 1973. 224. (.7 and 31) were observed in this activity in the morning and another flock of 17 was seen in the-evening. Occasional small flocks, of"10 to 12 birds . were also seen to leave the marsh. The following day, a flock of over 120 . mallards.was seen.flying low into the marsh in the afternoon, followed by flocks of 20 and 6. Many of these appeared to land in the Public Shooting Marsh. Based on the hatching dates for this study area (see Section 6.2.2) and assuming'a similar date for the Fraser Valley as a whole, these flocks could only be comprised of adult birds. Thus, these apparently daily flights were, comprised of non-breeders and birds that finished or abandoned nesting for this season. As the spring freshet and heavy rains had combined to cause some seasonal flooding in the P.itt Valley and adjacent Fraser Valley at this time, I believe the observed movements were potential moulters using the sheet water in the farmlands to exploit a sudden Iy avai IabIe food source superior to that found in the marsh. Once, the sheet water disappeared, I suspect the majority of these birds spent most, if not a l l , of the succeed-ing days in the marshes until- onset of the moult made aerial travel impossibl It is most difficult to state with any certainty the origin or.numbers of either mallards or wood ducks moulting in the' marshes. However, using calculations for estimated number of. pai rs in the study area in 1973 (see Table Vl-3), it would appear that there is an egress of birds into the marshes from elsewhere. Extensive banding, colour marking, and perhaps radio telemetry would be. necessary to determine this. Although a total of 69 adult mallards and wood ducks were banded.prior to. July 22 only I flightless bird of each species was trapped and the first of these not until July 12.'-In addition, only once were fI ightI ess ducks, in this case a drake and a hen ma I Iard, surprised adjacent to the traps.' Thi undoubtedly reflects the extreme wariness that flightless birds develop, a 225. condition noted by other workers (Hochbaum, 1944; Grice and Rogers, 1965). Examination of the trapping results for July shows the expected progression of the moulting season with an increasing number hens of both species journeying to the marsh upon completion of natal duties and subsequently being caught in the traps. ' There is, of course, no way of knowing exactly when the last of the adults finishes moulting in the marshes. However, there appears to be s t i l l a fair number present well into the third week of August.- This observation is based upon the capture, by my retriever, of two adult hen mallards and one adult drake wood duck in the span -of approximately five minutes near the centre of the Sturgeon Slough Marsh on August 21, 1973. I estimated one of the mallards to s t i l l be 7 - 10 days away from attaining flight, based on the length of her new primaries. Thus, in 1973, at least, some adults probably did not gain flight until early September. There is a. po'ss ib i I i ty that these late moulters may be vulnerable to predation because the..bulk of the marsh is dry or has only a few inches of water at this time. This was Undoubtedly a factor in the very quick capture by the dog of the two mallards and one wood duck mentioned earlier. Presumably, some of the larger mamma-lian predators would enjoy a similar advantage at this time. /'(b) Moulting Use by Teal: Considering that cinnamon and blue-wing teal constituted approximately a third of the local nesting popuI at ion in the study area, their apparent absence as moulters is somewhat surprising. It is not known if this species was perhaps located in a less extensively checked portion of the study area, such as.the Public Shooting Marsh, or whether they move to an entirely diff-erent area. One note of interest in this regard was the discovery of a number of .green-winged teal utilizing the remnants of former sloughs just north and 2 2 6 . e a s t o f N e t h e r l a n d s F a r m . M o s t o f t h e d u c k s I f l u s h e d w h i l e w a l k i n g up t h e s e s l o u g h s w e r e t e a l a n d a t l e a s t 50% o f t h e s e w e r e g r e e n - w i n g e d t e a l . One f l i g h t l e s s g r e e n - w i n g e d t e a I o f unknown a g e was s e e n s k u l k i n g a h e a d o f t h e dog a n d o n e f l i g h t l e s s a d u l t hen was c a p t u r e d i n t h i s m a n n e r . Why t h e s e . t e a l w e r e a t t r a c t e d t o t h e s e p a r t i c u l a r s l o u g h s i s n o t known t o t h e w r i t e r . P e r h a p s i t i s some a s p e c t o f t h e c o v e r i n t e r s p e r s i o n o r t h e p r e -s e n c e o f q u i t e a few l o a f i n g s p o t s , r e l a t i v e t o t h e m a r s h e s . W h a t e v e r t h e r e a s o n s , a n a n a l o g o u s s e t o f c i r c u m s t a n c e s c o u l d a c c o u n t f o r t h e a b s e n c e o f c i n n a m o n o r b l u e - w i n g e d t e a l f r o m t h e S t u r g e o n S l o u g h M a r s h . • . As m e n t i o n e d e a r l i e r , f u r t h e r s t u d y i s n e c e s s a r y b e f o r e t h e m a g n i t u d e o f t h e r o l e t h e P i t t V a l l e y m a r s h e s p l a y i n p r o v i d i n g a s e c u r e m o u l t i n g a r e a f o r some s p e c i e s . o f p u d d l e d u c k s , i s r e a l i z e d . . N e v e r t h e l e s s , some p o s t u l a t i o n s c a n be made, b a s e d on c u r r e n t k n o w l e d g e o f w a t e r f o w l r e q u i r e m e n t s d u r i n g t h e m o u l t a n d t h e a v a i l a b i I i t y o f same i n t h e L o w e r F r a s e r V a l l e y . A s f a r a s i s known, t h e m a r s h e s o f t h e s t u d y a r e a , r e p r e s e n t t h e l a r g e s t a c r e a g e o f f r e s h w a t e r m a r s h r e m a i n i n g i n t h e L o w e r F r a s e r V a l l e y . T h o u g h p l a g u e d by a s o mewhat v a r i a b l e w a t e r r e g i m e , t h e s e m a r s h e s o f f e r t h e b e s t c o m b i n a t i o n o f f o o d , , c o v e r , a n d i s o l a t i o n a v a i l a b l e . A s s u c h , o n e ' w o u i d e x p e c t t h e m t o become a f o c a l p o i n t f o r many p o s t - n e s t i n g p a i r s o f m a l l a r d s a n d wood d u c k t h r o u g h o u t much o f t h e L o w e r F r a s e r V a l l e y , i f o n l y f o r l a c k . o f an a l t e r n a t i v e s i t e . T h i s i s n o t t o i m p l y t h a t b i r d s c a n n o t o r do n o t u t i l i z e , t o some e x t e n t , t h e r e m n a n t s o f s l o u g h s , c r e e k s and. m a r s h e s . ..that a r e s c a t t e r e d a b o u t t h e L o w e r ' F r a s e r V a l l e y . H o w e v e r , many o f t h e s e l a c k o n e o r more o f t h e b a s i c r e q u i r e -m e n t s , u s u a l l y s i z e a n d i s o l a t i o n , a n d t h u s are. l i k e l y u n a t t r a c t i v e t o many b i r d s . S i m i l a r l y , f r o m t h e w r i t e r ' s own e x p e r i e n c e s , a n unknown number o f d u c k s u t i l i z e t h e F r a s e r m a r s h e s d u r i n g t h e f l i g h t l e s s p e r i o d . Y e t t h e d a i l y t i d a l f l u c t u a t i o n s may w e l l d i s c o u r a g e many b i r d s t h a t w o u I d . o t h e r w i s e u s e 227. t h e s e a r e a s as r e f u g e d u r i n g t h e m o u l t . As mentioned p r e v i o u s l y , I do not know i f t h e P i t t marshes p r o v i d e t h e a l t e r n a t i v e t h e s e , b i r d s seek o r i f . t h e y f l y e l s e w h e r e t o m o u l t . However, t h e p r e s e n c e of more a d u l t b i r d s d u r i n g t h e m o u l t i n g p e r i o d t h a n t h e a d j a c e n t a r e a s u p p o r t s as b r e e d e r s i n d i c a t e s a d e f i n i t e , and I s u s p e c t c o n s i d e r a b l e , i n f l u x of b i r d s from e I s e w h e r e .and t h e l o g i c a l s o u r c e t h e a d j o i n i n g ' F r a s e r VaI l e y . F i n a l l y , i t i s r e a s o n a b l e t o assume, I t h i n k , t h a t t h e s e marshes a r e g o i n g t o i n c r e a s e i n importance as s i t e s f o r m o u l t i n g a d u l t w a t e r f o w l i n t h e v e r y near f u t u r e . T h i s s t a t e m e n t i s based on t h e b u r g e o n i n g wood duck p o p u l a t i o n i n t h e F r a s e r V a l l e y as a r e s u l t o f numerous n e s t i n g box p r o j e c t s and on t h e p o t e n t i a l o f t h e Canada GooseCBranta c a n a d e n s i s ) r e s t o r a t i o n p r o g -rams c u r r e n t l y underway i n t h e same a r e a . D r o p p i n g s and d i s c a r d e d p r i m a r i e s and s e c o n d a r i e s i n d i c a t e t h a t s e v e r a l geese moulted i n S t u r g e o n S l o u g h Marsh . i n 1.973 and t h i s may be t a k e n as'a p r e l i m i n a r y i n d i c a t i o n t h a t c o n d i t i o n s a r e b a s i c a l l y a c c e p t a b l e t o t h e s e b i r d s . C e r t a i n l y , I would e x p e c t t h a t ' a s a f e p l a c e t o . m o u l t w i l l be one of t h e major problems t h e goose r e s t o r a t i o n p r o -gram w i l l f a c e and one t o which few a r e a s , b e s i d e s t h e - P i t t marshes, can p r o -v i d e an answer. 6.3.6 M i g r a t i o n P a t t e r n s and W i n t e r i n g A r e a s o f L o c a l Ducks To p r o p e r l y manage a h i g h l y m o b i l e r e s o u r c e such as m i g r a t o r y w a t e r -fowl i t . i s not s u f f i c i e n t t o m e r e l y u n d e r s t a n d t h e c o n d i t o n s under which t h e s e b i r d s r e p r o d u c e . In a d d i t i o n , t h e w a t e r f o w l manager s h o u l d a l s o be aware of t h e c o n d i t i o n s and p r e s s u r e s t h e b i r d s a r e s u b j e c t e d t o d u r i n g mig-r a t i o n and w h i l e on t h e w i n t e r i n g grounds. In w a t e r f o w l r e s e a r c h , t h e most . w i d e l y used management t o o l t o d a t e i n t h i s . r e g a r d has been t h e banding of a r e p r e s e n t a t i v e number of t h e p o p u l a t i o n under i n v e s t i g a t i o n and t h e subse-228. quent analysis of the recovered bands. Before embarking on such a program in the study area we were faced with a major decision.. Would the acknow-. ledgely low resident population enable us to capture and band a large enough sample to permit statistical evaluation of the results? Based on an estimated direct recovery rate of.10 - \5% and an arbitrary estimate that a minimum 50 recoveries from each species present would be necessary, we would be faced with the task of banding'approximate Iy 1,300 to 1,500 ducks. This, of course, at the present level of waterfowl productivitiy '• in the study area, was a virtually impossible task. Nevertheless, I decided that, with a maximum effort, we co.uld obtain enough, recoveries for mallards and wood ducks to at least indicate possible trends in migration route and wintering ground selection. This decision was based on the premise that any extension of knowledge in this regard, was preferab le to the status quo. (a) Wood Duck Movements: The recovery of ten bands from adult wood duck within the Pitt Valley and another from the nearby. Fraser marshes as opposed to two from Oregon and one from California would suggest that a ..substantia I segment of the adult population may be non-migratory.; Another possibility would he that the adults migrate through, and winter at, areas subjected to far less hunting pressure;than the areas.frequented by juveniles. However, there are several indications that the.first possibility is the more plausible. During the winter months of this study a large number of wood duck were known to have overwintered at several locations adjacent to the study area. Several hun-dred were reported at Douglas Island, situated at the confluence of the Pitt and Fraser' rivers. In addition, approximately 100 and 200 birds res-pectively utilized the refuge areas created by two waterfowl propagators. 2 2 9 . The first of these is situated on the west, bank of the Pitt River, adjacent to the Pitt River Bridge. The other,,Coniagas Ranches, is located on the South Alouette River, approximately I? miles south of the Ag. I habitat type of the study area. For several years prior to this study the Douglas Island and Pitt River Bridge flocks were as yet not established and at that time as many as 300 to 400 birds were reported utilizing Coniagas Ranches. The birds would apparently spend the day feeding on the grains distributed to the captive waterfowl in the refuge area. At dusk, they would take off en . . masse and fly in a north-easterly direction. At dawn a similar number of birds could, be observed returning from the same direction. Unconfirmed reports are that these birds roosted overnight on one or more of the lakes located in the U.B.C. Research Forest. Though there is no evidence atithis time as to the age compostion of these flocks their presence indicates the possibility that an unknown number of the local population are non-migratory. Confirmation.or refutation of this awaits several more years of extensive, summer banding followed by capturing a number of these wintering birds and examining them for bands. The date and location of recovery from resident adult wood ducks would indicate that the bulk are taken within their natal marsh and that this harvest occurs within.the first two weeks of the season. The almost total absence of I oca I • returns after the end of October and the relatively few returns from points south during November and December could be explained if the adults responded to.the hunting pressure by quickly retreating to local areas where hunting harassment' is absent or minimal. All of the areas pre-viously described as holding relatively large numbers of overwintering wood ducks, this requirement. In addition, they are a ready 230. source of feed and water, suppIied inadvertently by the propagator, through-out the winter months. As with the adults, the recovery of banded juveniIe wood ducks revealed that the B.C. kill was entirely restricted .to the Pitt Valley. Similarly, the bulk of these juveniles were taken by the end of October. However, the recovery of 64$ of the total juvenile bands returned from Oregon, and Calif-ornia reveals that a definite migration of juveniles occurs,, the bulk of it during the latter part of November and probably the early part of Dec-ember. In the case of both adult.and juveniles, their destinations appear to be the Willamette Valley in Oregon. (7 recoveries) and the Central. Valley of California (5 recoveries). It is interesting to. note that all the adult .and. 7 of 9 juvenile recoveries obtained from the U.S. occurred during a chronologically similar period. This apparently reflects Hochbaum's (1955) contention that the bulk of juvenile ducks reach the wintering grounds in company.with some experienced adults. The same author a I so states that "Some young ducks reach the wintering-range in their primary wanderings, getting there before many adults have arrived." This could well explain the two juvenile recoveries, one from Oregon and one from California, that occurred on Oct. 25 and 28 respectively, in the.fall of 1973. As is evidenced by the latter recoveries,. I suspect that an unknown segment of the juveniles move out of the Pitt Valley prior to the second week in October. This view is supported by considering the age ratio of the wood ducks presented at a hunter check station set up in the study area on opening day of the hunting season in 1972 and 1973 (see Appendix II). Though there were more juveniles than adults in the opening day bag in 1972 the aduIt:juveniIe. ratioof 1:1.57 is conspicuously low compared to that of the other common species for which aging data was obtained 231 . (i.e. Pintail, Widgeon and green-winged teal). Such a disportionate ratio could not have been the result of low wood duckling survival, for earlier calculations had revealed an average Class I 1 brood size of 5.1 ducklings in 1972 (see Section 6.2.3). However, if a number of juveniles had departed from the area since fledging and prior to the second Saturday in October, while the adult population remained fairly static, then such a ratio is plausible. The 1973 figures indicate further that, by the second Saturday of October, the wood duck population in the Pitt Valley consisted of fewer juveniles than one would expect to find had the entire area's production . been present. The virtual absence of local juvenile wood duck recoveries after the end of October para I I els.the sequence of adult recoveries described; earlier. This would suggest that by late October, the juveniles are forced by local hunting pressure to retreat to areas such as Coniagas Ranches and Douglas Island where harassment is minimal. A similar reaction was suggested ear- . lier for the adult component of the population. Both adults and juveniles apparently remain on these or similar areas for approximately 2 to 3 weeks during which they undergo little hunting pressure. Then, in mid-November, an unknown- proportion of the juvenile population, accompanied by a lesser • number of adults, apparently migrate to Oregon and California. The exact route of migration is unknown. However, the complete lack of recoveries from Washington followed by a series of returns from the lower reaches of the Columbia River and the adjacent Wi I Iamette VaI Iey suggest the wood ducks may fly direct from the Pitt Valley, to these areas. At this point in time we do not know if the California recoveries are from birds that have filtered south after• initiaI Iy•arriving in Oregon or if these also represent a direct flight from the Pitt Valley. 232. (b) Mallard Movements: The re I atively small number of resident mallard recoveries severely restricts discussion of the movements of this species. As a II the recov-eries obtained were from juveniles it would appear that this segment of the population, remains at, or.fairly close to, the area of natal experience until at least early October. This is further substantiated by the observations of two ma I I ards marked w ith nasa I saddIes (see Sect i on 6.1.5). One was seen on the study area on October 5, 1973 and the other-at the mouth of the Fraser River during the third week of October, 1973. Based on the limited data available very little hunting pressure is exerted on mallards banded in the Pitt Valley after the end of October. Whether the birds have located an area or areas, locally or elsewhere in the Flyway, where they are subjected to little or no hunting pressure in unknown. Munro (1943) has described the lower Fraser Valley and adjacent counties in Washington State as holding the greatest concentration of wintering mallards on the Pacific Coast. He also states that, the main flights reach this area in.November.' The concomittant decrease in recoveries from local birds could reflect the arrival of these flights and the resultant distribution of hunting pressure over a much larger population of birds. This, of course, would reduce the possibility of an encounter, particularly in view of the small number of JocaI ma I lards banded. 6.3.7 Waterfowl Harvest Data in Pitt and Alouette Polders It is apparent from the data presented (see Tables V I -13 and V I — 21 that, in the Pitt Valley, quality hunting, in terms of birds bagged/hunter day, is enjoyed by a relatively small segment of the hunting public. Nor is it a coincidence that this segment almost exclusively consists of members of one or more of the gun.clubs operating in the area. There are a number of 233. reasons for this disparity and one of the most important can be found in Table V I — 13 - From this it is evident that the intensity of hunting on the 'most successful of the clubs is but a fraction, per unit area, of that found on the adjacent public marsh. Admittedly, a comparison restricted to one day, and opening day at. that, probably reflects the disparity at a maximum. Yet casual observations throughout the Fall and Winter' of 1972 and 1973 revealed.a proportionately greater pressure on the public marsh until, well into November of each year. This is undoubtedly reflected in the calculated hunter success rate in the two areas (see Table VI —14). Thus, I would suggest that the relatively low quality of hunting in the Public Shooting Marsh may be directly attributable, to excessively heavy hunting pressure. There is, however, a notable exception to the aforementioned condition. This results when a supply of feed, natural or ar t i f i c i a l , is so attractive that waterfowl persist in attempting to use the area despite heavy hunting pressure. This apparently was the situation existing at Coniagas Ranches in 1972 and 1973, Prior to 1972, the waterfowl kill was negligible on this -215 acres of mixed crop farmland. Then, in 1972, the owner created a 9-acre pond in one field and planted it to wild rice (Zizania spp.) as an experimental commercial venture. Apparently this source of feed and water, located in the generally waterless Lower Fraser Valley of late .summer, was highly attractive to waterfowl. This is reflected in several counts of more than 2,000 ducks on the pond, in late August and during September. During the:1972 hunting season, the pond was hunted on eleven of the first twenty-three days of hunting, with as many as six hunters present at the pond at one time. Yet despite this very heavy pressure, eighty ducks were bagged in this time, for a success rate second only to that of the Sturgeon Slough Club. From that, point on, the shooting tailed off, presumably because of the continual harass-ment. 234. In 1973, additional ponds were built and a total of 27 acres of wild rice planted. During August and September intensive waterfowl use was dis-couraged by the use.of scare guns and by maintaining a water level high enough to discourage feeding by dabblers. This prevented over-utilization of the available feed prior to the hunting season and was designed to len-gthen the overall period of use of the area. In early October, the scarers were removed and the pond partially drained thereby greatly increasing the . feed av.ailab Ie to waterfowl. Once hunting began, shooting was restricted to one 16-acre pond. Four blinds were used with a maximum of two hunters per blind at any one time, and shooting was limited to Wednesday, Saturday, and Sunday of each week. Nevertheless, the area was heavily hunted with up to 14 guns, shooting over the pond on a given day, and a total of 188 hunter-days for the season. Yet waterfowl continued to use the pond.until mid-December, at which point a cold snap froze the ponds. The season's tally was 715 ducks and the success rate of 3.74 ducks/hunter-day very nearly equalled that of the Sturgeon SloughClub (see Table VI-15). Thus we have .in the Pitt Valley the full gamut of hunter effort and success including (I) heavy hunter density and low success, (2) light hunter density and high success and (3) heavy.hunter density and high success. The level of hunting intensity that an. area can support and s t i l l maintain quality shooting will, of course, vary from area to area. Rose-borough (1961) recommended that hunter density on provincially controlled public hunting areas in Ontario be based on one hunter per 25 acres and shooting. .I imited'to 4 days per week. Based on an average density of 36 acres per hunter per blind unit in a number of western state areas, Morris (1971) recommended at least 30 acres per hunter per blind unit for a compar-able area i n Br iti sh Co I umb.i a . Assuming two hunters per blind, this, would 235. require 60 acres per blind location. If we use the latter figure as a base, then the 12 club, hunters in the. Sturgeon Slough Marsh on opening day, 1973, were exerting a pressure equivalent to one blind per 133 acres (assuming two hunters per blind and use restricted to 800 of the 3,475 acres available).. Conversely, to accommodate the opening day count of 120 hunters in the Public Shooting Marsh, at two hunters per blind, would have required 60 b I i nds. On the 582 acres ava i lab Ie th i s wouId resu11 in one blind every 9.7 acres. Under such intensive pressure, it is not difficult to understand., why the ducks soon restrict their movements to the adjacent Sturgeon Slough Marsh. This, in turn, is reflected in the much better shooting enjoyed by the club members hunting that area. However, lack of hunting pressure a I one will not necessarily result in quality shooting on a given area. If this were so then based on acres/ hunter (see Table V1 — 12) the five other.clubs in,the study area would also enjoy considerable success. Yet according to an earlier study (Erickson et_ a I 197,2), their kill varies from 1.0 to 1.7 ducks per hunter-day, con-siderably lower than the almost 4.0 birds per day enjoyed by the Sturgeon Slough Club over the season. It is also quite possibIe that these figures are high, for as noted by the authors, they are based on estimates rather than recorded figures. In my opinion, the much lower bird availability of these areas reflects the habitat in which they are located. Simply put, they are not attractive to waterfowl for.much of the fall and winter, due " to lack of feed, water, or a combination of both. Of the 3,675 acres controlled by these five clubs only 565 acres are located in the unpumped area of the polders. , Hence, there is little chance of sheet water appearing on the pumped lands until the heavy fall rains of November. Thus, any waterfowl' attempting to utilize these areas prior to the 236. •latter time are limited to the water contained in a few .s loughs, and'the drain-age ditches. Such conditions are apparently unattractive to large numbers of waterfowl and shooting at this,time is limited to the occasional jump-shot from the ditches and sloughs. Similarly, the. large acreages of pasture on several of the clubs offer a Iimited attraction to mallards, pintail and green-winged teal. Due to their habit of grazing, widgeon will utilize such areas but generally not until sheet water is present. In addition, several clubs, noticeably the Lower Mainland Club and the Alouette Club, have large stands of almost impenetrable hardhack that is completely useless from a waterfowl utilization standpoint. Thus, waterfowl flying into the Pitt Valley in the early fall naturally focus on the marshes and peat ponds loca-ted at the northern end of the polder, for, until November or later, these are the only areas offering both feed and water in a combination acceptable to waterfowI. In effect,then, many of the clubs in the study area do not, from a waterfowl standpoint, enjoy the success attributed to them by non-club hunters. In fact, it is my opinion that a know IedgeabIe.hunter has a much . greater chance of shooting ducks in the Public Shooting Marsh on opening day than do most of the club hunters (excluding Sturgeon Slough. Club and Mallard Gun Club). For example, two limit bags of eight birds each were recorded from the Public Shooting 1972.while in 1973 two parties of two hunters each took fifteen and eight birds respectively from the public marsh. Conversely, no opening day limit bags and only one of eight birds, by two hunters, was recorded for members of the clubs under discussion during the two years of the study. However, by belonging to a club, the members do ensure themselves of a place to hunt under conditions a little more aesthetically pleasing than one experiences in the public marsh on many occasions. In 237. addition, their areas do provide some waterfowl shooting later in the season. At this point, I feel that a discussion of feed as an attractant to waterfowl in this area would complement the discussion of hunting in the Pitt Valley. Prior to the most recent recIamation•work in the early ' f i f -ties, the major source of natural feed, according to long-time hunters in the area, was smartweed. The many shallow sloughs transversing the meadows provided ideal habitat for this plant and by all accounts it grew profusely.. Though many of these sloughs were relatively short-lived, due to vegetative succession,: periodic floods induced by.the spring freshet resulted in recur-rent creation of new habitat favourable to smartweed. No doubt, this was not the only source of seeds available to waterfowl. Munro (1943) found that seeds, chiefly of aquatic plants, constituted "100$ of the food items in gizzards he examined from Pitt Meadows. The species most commonly found was Carex vesicar ia wh i Ie other species identi f ied were Eleochari s obtusa, Polygonum hydropiper'and Menyanthes trifoliata. The author further notes that the seeds of smartweed and other members of the Polygonaceae are eaten in large quantities in Pitt Meadows and are said to impart a distinctive flavour to the flesh. However, despite many verbal recoI lections, of extensive waterfowl use of this study area at the time little has been documented. Several excep-tions are of interest. During the last week of January, 1948, a survey by-the local conservation officer revealed counts of the following: 3,600 ma I Iards, 1,000 widgeon and 400 green-winged teal. . A similar count on January 12, 1951 censused 2,000 ma I Iards, 1,500 widgeon and 500 green-winged teal. As both these counts.were prior to reclamation, which started later in 1951, it is assumed that these birds were feeding primarily on,natural feeds. Conversely during a similar period in 1972, and 1973, I was never aware of more than 238. I',000 to 1,500 ducks in the area and usually far less than this number. . By 1953 the conservation officer, who had been stationed in the area for close to thirty years, was noting a progressive decline in the number of ducks using the area. CoincidentaI Iy, approximately 2,000 acres in the southern portion of what was now known as Pitt Polder was subject to water-table control and undergoing extensive, land reclamation. Thus, many acres of meadow and slough were eliminated as a source of waterfowl feed. Then followed bulldozer and plough and, in. 1954, a large acreage was in crops. Initially, it.may be that the subsequent planting of crops partially off-set the loss of natural feed in the area. Indeed, over 8,000 ducks, large ly'Pi ntaiT., were apparently attracted to 650acres of oats planted in 1954. In addition, potatoes and market gardening of vegetables provided an additional source of feed. However, by the I ate 'fifties, the reclaimed land was committed to dairying and the resultant planting of pasture apparently reduced the feed capabilities, as far as waterfowl were concerned, to a fraction of its former level. In any event, the regional conservation officer was moved to' report on January 2, 19757 that "... there was a decided decrease in the numbers of migratory game birds frequenting -this District and I would say that during my 29 years stationed here, it has been the worst on record." Thus, it would appear that a decline in the number of ducks using the area coincided with alienation of approximately 45$ of the area to a mode of agriculture that provides the way of feed for waterfowl. Today, seeds of various aquatics are s t i l l probably a source of feed to waterfowl in the Sturgeon Slough and Public Shooting marshes. However, with the current unstable water levels in these areas, one is led to wonder what effects this may have on seed product ion and avai IabiIity. 239. A final aspect of feed and waterfowl ,in the Pitt Valley is the use, by some clubs, of crops and harvested grains to attract waterfowl to various areas. The Alouette, Mountairiview and, recently, the Sturgeon Slough clubs have a II grown various crops specifically to attract waterfowl. The acreages involved size from less than an acre to 40 to 50 acres and generally consist of buckwheat, smartweed, potatoes or corn. In addition, the Sturgeon Slough Club usually, places several tons of low grade grains in the marsh, via a helicopter. In 1973, this amounted to five tons of bait, which was placed in accordance with regulations of the Migratory Bird Act:governing such practices, .However, because of water depth and the canopy effect of existing vegetation, I suspect that the bulk of this feed is unavailable to waterfowl. In. 1972, the Alouette Club also used grain dumped in ditches to attract waterfowl but this only amounted to a few hundred pounds and was largely de-' voured before the area could be legally shot. The four species constituting the largest proportion of the waterfowl harvest in the Pitt Valley are also the four most frequently encountered on the Fraser Ri.ver marshes, from September to May of each year (Burgess, 1970). Similarly, these species, namely mallard, pintai I,•widgeon and green-winged teal also account for the greatest proportion of the annual waterfowl kill in British Columbia (Cooch, Kaiser and Wight,, 1974). Within the valley as a whole there are apparent regional disparities • in the harvest of several of these species (see Table VI-1'5), Most notice-able is the relatively low number of mallards taken at the Coniagas Club, and, in 1973, the surprisingly, large number of pintail taken there. Two possible factors causing such a disparity could be relative species availability and hunter selection. In the case of the latter, annual monitoring of the kill in the Fraser 240. Valley has, over the years, established the mallard as accounting for approx-imately 40$ of the local harvest. This occurs despite the fact that annual fall and winter aerial surveys of the Fraser marshes,show that mallards aver-age, less than 20$ of the four main species present at any given time. Thus, it would appear that mallards are selected by hunters in the Fraser Valley and as there is no indication that the average hunter at Coniagas differs in his preferences, the low mallard kill there must reflect availabiIity. Yet apparently this low ava i I ab-i l-i ty did not exist elsewhere in the Pitt Valley for the mallard bag there was generally in keeping with expected levels. I w.ou I d also suggest that re lat i ve ava i lab i I i ty accounts for the disparity in the proportion of pintail taken in various parts of the Pitt Valley. The question that must be answered, from a management standpoint, is "What . causes this variation in species.distribut ion?" There is little in the way of quantitative data to apply to this.prob-lem. However, I would suggest that (qua Iitatively) the answer may well lie in the preferences of some waterfowl species for certain habitats. Experience has shown that mallards, green-winged teal, and to a' lesser extent, widgeon, have no aversion to utilizing relatively closed-in habitats such as swamps, sloughs and 'flooded creek bottoms. In this respect, the fairly dense vege-. tation comprising the marshes and wildlands of the study area could be'expec-ted to be relatively attractive to the species concerned. This is supported by the observations of the late Frank Urquhart, who patrolled this area for. thirty years as a Provincial Game Warden.. In 1951, he wrote, "The Sturgeon Slough chiefIy a Mallard, Widgeon and Teal area and very few Pintail are ever found in the.local ity." Conversely, the pintail is recognized, by experienced waterfowIers, as a bird,of open areas. Hence, the large open fields of the croplands seem to attract the bulk of these birds in the Fraser 24 1. Valley. Similarly, by far the greatest proportion of pintail counted during the"aerial surveys each fall and winter are censused in the sandy expanses of Boundary and Mud Bays in apparent preference to the marshes of the Fraser deIta. Assuming these observations to be valid it would appear that the location, at Con.iagas Ranches, of 27.acres of pondage within the comparative barrenness that is typical of most cropland in fall and winter is highly attractive to pintail. Similarly, despite the abundance of feed in the form of wild rice and other aquatic seeds, mallards do not seem attracted to such a habitat in proportion to their numbers in this area. Eventual con-firmation of such species preference for. certain habitats could have- signi-ficant management implications in this area- in-the future. There are several other disparities in-the species composition of the harvest that bear examination. The 1972 figure of 49$ teal in the bag at Coniagas also refIects availabi Iity. However,- because the numbers of birds involved was less than 50, I feel this does not indicate any abnormal res-ponse of green-winged teal to the habitat involved. More likely it reflects a combination of the ubiquitous nature of the teal in.selection of habitat and the opportunity for hunters to avoid going home, empty-handed. Apparently the.high utilization of this area by pintail in 1973 took some hunting pres-sure off the teal, for the I attar's presence in the.kill at Coniagas was much nearer that experienced elsewhere in the Pitt Valley. The obvious exception to this is the Sturgeon Slough Club where members are relatively selective in their shooting. Hence, their limited harvest of.the much smaller tea I refIects selection for the three larger species, i.e. mallard, pintail and widgeon. In particular, mallards are sought after by club members, as evidenced by the proportion of mallards in both the opening day and season harvests. 242. In 1972, mallards constituted a relatively low 35$ of the season's bag. However, this probably refIects errors in collection of data during the first ten days; of the season. Similarly, this may account for the very high proportion of widgeon accounted for in 1972. SeveraI pre-season surveys .had indicated simi lar use of the Sturgeon Slough Marsh and the adjacent pub I ic marsh, by mal lards. Hence, the difference in per cent mallards taken on these adjoining areas is taken as further evidence of the effect of hunter selectivity and hunter density on both success and species composition of the ki I I. Of particular management interest is the number of gadwa I I shot in the study area. As reflected in the openi ng day ki II, there are apparently few of this species present in early October. However, increasing numbers are taken towards late October and gadwa I I then appear in hunter kills fairly consistent Iy through the remainder of the season. Further investigation has revealed that the wintering population-of gadwa I I numbers 300 to 400 birds. They apparently limit their activities to the Sturgeon Slough and Public Shooting marshes and'have not been reported elsewhere in the' polder in.any numbers. They particularly frequent the area adjacent to Mountain Blind in the Sturgeon Slough Marsh and the bulk taken by club hunters come from this location. As these were rumoured to be birds from several recently established nesting colonies on the Fraser marshes, extensive banding at one' of the largest of these colonies, Iona Island, was carried out in August, 1973. However, the return of one band from the Pitt Valley during the fall and winter: of 1973 would indicate that the birds frequenting this.area apparent-ly originate other than from the Fraser Delta. • In 1973, thirty-five gadwaI I were reported taken in the Sturgeon Slough Marsh and four from the Public Shooting Marsh. However, the latter represents birds reported in the National Wing Survey and as. such are only a relatively sma I I samp Iing of the actual 243. number taken. Thus,.local waterfowl managers .might do well to begin moni-toring the harvest of this apparently discreet wintering population until i t s origin and production capabilities are determined. In the case of the wood duck harvest there is a noticeable decrease between the opening day kill and that of the entire season. . This would appear to confirm my earlier conclusion that, with the advent of hunting season, wood ducks soon, become unavailable to local hunters (see Section 6.3.6). Nevertheless, the overall proportion of wood ducks taken during the season rose slightly in 1973 and probably reflects the increasing number of wood ducks being produced in the Pitt Valley. There appears to be little known of the origin of the'waterfowI species, other than wood duck, that comprise the harvest in the Pitt Valley. Munro (1943) analyzed 3,387 returns from mallards banded during the fall and winter at three Locations in the Lower Fraser Valley, including one at Pitt Meadows, between 1928 and 1940. From these.he cone Iuded that these wintering ma I a wide summer dispersal to nesting grounds in interior British Columbia, Alberta and Alaska. However, recoveries in the spring • and summer at these locales merely indicates the presence of the bird at the time but does not.necessariIy mean it was, or intended, to breed there. In an attempt to pinpoint more accurately the origin of mallards shot in the. lower Fraser Valley between 1924 and 1972, I analyzed data from 1968 band returns. Of these, 58 had been banded on their natal marsh as flight-less young. The origin of these birds is shown in•Tab Ie V I-22. The bulk of the remainder had been banded in the Fraser Valley during fall and winter banding operations and thus were of unknown origin. Because, from a geo-graphical standpoint, the Pitt Valley is included i.n the area designated as the Lower Fraser Valley, .1 assume that ma I Iards using one are as likely to Table VI-22: Origin of Mallards Banded as Flightless Young and Subsequently Recovered in Lower Fraser Valley, 1924-1972 Origin No. Ma 1 1ards Occurrence 1nterior B.C. 19 32.7 Fraser Delta 15 . 25.9 Puget Sound Area 12 20.6 Central Alaska • 3 5.2 Yukon-Kuskowim Delta, Al. 1 1 -7 Copper River Delta, Al. 2 3.5 Central Washington 1 1.7 Saskatchewan 3 5.2, Lesser S.lave Lake, Al'ta. 2 3.5 TotaIs 58 • 100.0 245. utilize the other. Therefore, the 58 returns could be considered repre-sentative of the study area also. In closing, it should be remembered that the data in Table VI-22 simply indicates nine geographical areas in North America that produced mallards which were subsequently shot in, or adjacent to, the study area. Insufficient banding data was examined to indicate whether, these areas are the only known sources of local wintering mallards. 246. 6.4.0 Management Suggestions At the conclusion of this study, it. was apparent that certain manage-ment opportunities exist for enhancing waterfowl utilization of the various habitat types. The scope and effort directed. toward such opportunities, however, are governed by the primary land use designated to a given area. In the pumped areas, i.e. Ag. I - west, .Ag. ' I. - east, Ag. Hand Dense Wildlands, present and future committment to agricultural development pre-cludes many management possibilities.. The unpumped habitats, i.e. Open Wildlands, Sturgeon Slough Marsh and Wildlands and the Public Shooting Marsh1 offer extensive opportunities for wetland management, assuming their official designation for that purpose. Thus, the following management suggestions for the respective habitat types are offered, based on the aforementioned I and use pri or i t i es. PUMPED HABITATS Ag. I - west and east: Use of this area by migrating and wintering waterfowl could undoubtedly be increased by the use of lure crops and. construction of ponds and sloughs. Such attractants have been used in' recent the.gun club leasing the area. However, small acreages involved and excessive gunning pressure-apparently reduce the maximum .benefits. Discussion with the tenant farmer has elicited his indicated willingness to plant feed crops for waterfowl pro-viding there is compensation for labour and land. Thus, a commitment of funds and to common-sense hunting practices seem the basic requirements for increased fall and winter waterfowl use. However, the private nature of the hunting on this area necessitates that these initiatives come from the 247. i nd i v i dua I s rece i v i ng the greatest benef it, i.e. the gun club members. From the standpoint of providing. mou11ing and staging areas for post--breeding waterfowI,.this habitat type has negligible benefit. This may not always have been the case. However, the disappearance of most, if not a l l , sloughs and wet depressions with agricultural development has eliminated the basic cover requirements of flightless waterfowl in this area. Under ex.isti ng land-use. p.ractices, the greatest opportunity for man-agement in Ag. I concerns nesting waterfowl. In the case of ground-nesting species, i.e. mallard, cinnamon and blue-winged teal, modification of certain agricultural practices may increase production to some degree. .For instance-, cutting of ditchbank cover, when necessary, should be done prior to Apri I I.. This would prevent unnecessary destruction of mallard nests, the peak initiation of which generally occurs after the first week of April (see Section 6.2.2). Burning along dykes and ditchbahks should be discouraged as it removes the litter layer required by nesting, waterfowl. If deemed necessary in certain areas, burning should be concluded prior to April I to avoid destruction of mallard nests. Cutting of hay in Ag. I generally takes place in early July, after the peak hatching period of cinnamon.and blue-winged teal (see.Section 6.2.2). Any future change to an.ear Iier . cut should prompt negotiations with the tenant farmer to delay as long as possible. Another management input, which would encourage ground-nesters, part-icularly teal, would be to modify road verge management. Ideally, post-poning the first cut until after July I should permit the bulk of the teal to hatch in most years. However, it has been indicated to me that the lodg-ing of rain-soaked grass onto the road constitutes a hazard, thus necessitating cutting in the first place. Therefore, if earlier cutting is necessary,. . perhaps it can be restricted to a two-foot strip immediately adjacent to the road. . In addition, setting of the cutting bar at a height of approximately 248. 12 - .18" should suffice to prevent lodging and s t i l l provide nesting.cover, should the disturbed hen return to the nest. The greatest potential for increasing duck production exists with the wood, duck, via erection of artificial nesting boxes. There are, however, a few ground rules' to consider before embarking -on . large-scale erection of nesting boxes. First, boxes should only be erected in locations that pro-vide nearby post-hatching needs, i.e..feed, water, brood.cover. Second, in-tensive experimentation with different styles of nesting boxes should be carried out in an effort to minimize starling use of the boxes. Until this latter problem is solved, boxes will have to be checked a minimum of once a week from-mid-ApriI until early July, or, until occupied by an incubating wood duck. The seriousness of the starling problem should not be underesti-mated. Apart from their direct effect on the ducks, the presence of huge .flocks of starlings in local blueberry fields later in the summer has been blamed on past nest box programs in the area. This has, in the last''year', resulted in deteriorating relations between wood duck propagators and some . land owners in the Pitt Valley. Thus, development of a starling-proof box would be good public relations as well as good waterfowl management.. . Suggested locations for, and density of, nesting boxes has been indi-cated in Appendix 10. Placement of boxes.on metal poles permits use of habitat that is adequate save for the presence of trees. Where available, the poles on which goose tubs have been erected can also he used to' support a box. As nest' initiation for wood duck.occurs in thethird week of April locally (see Section 6.2.2), there should be little conflict with nesting Canadas. whose peak hatch has usuaIly occurred by that time (Hatfield, 1974). Use of the borrow-pits takes advantage of the most suitable food, water and cover possibilities and permits a rapid but quiet method of checking 250. the boxes, via a canoe. In addition, the proximity of the South and North Alouette rivers to the pits enables broods to take advantage of short-term cover conditions (see Section 6.2.4) with a minimum of movement. Midderh Slough Is also a suitable area for erection of .nest boxes, (see Appendix 10). In.addition, placement of a stop-log water control where the slough flows into the borrow-pit could be used to create some excellent brood cover along the slough. At.present such cover only exists for a 3 to 4 day span at the peak of the freshet. Then the slough is drained once,pumping lowers the level of the borrow-pit. Artificial loafing sites could also be placed in the slough, for they would have little influence on drainage once a gate is erected. Ag.. II: . Unless some provision can be made to provide adequate brood cover in this habitat it would appear unwise to undertake an extensive nesting box program in this habitat type. With respect to ground nesting species, intensive agricultural development for dairying precludes any attempt to increase ma I Iard and teal nesting in the area. A possible exception would be .a moratoriurn on burning and cutting of road a I Iowances from April I to July I annually. Contrary to the situation in Alouette Polder, cutting of road allowances in Pitt Polder is handled by Pitt Polder Company and may be negotiable along the lines suggested above.. Dense WiIdiands: Due to lack of suitable brood-rearing habitat there would appear to be little purpose in erecting wood duck boxes in this habitat type. Simil-arly, the existing vegetative cover needs major modification before nesting by; mallards and teal will take place. Although a representative of the land-251 . owner has stated that there are no immediate plans to develop this land for agriculture, uncertainty precludes any large-scale expenditure of funds for waterfowl habitat improvement. Should some form of long-term lease be obtainable then both nesting and fall and winter.waterfowl use could undoub-tedly be intensified. UNPUMPED HABITATS Within their confines these areas contain some 4,000 acres of wetlands ranging from freshwater peat-bog. Though used the year round by waterfowl, it is apparent that the area is realizing but a fraction of its potential.. This is apparently due to a water regime that affects waterfowl both directly and indirectly. In spring and. early summer, flooding curbs breeding effort and success; Indian summers result .in extensive acreages drying up in early f a l l , and mid-winter rains flood large areas to a depth unsuitable for puddle duck use. Indirectly, the water regime has affected duck use by fostering a vegetational pattern that evolves towards decreasing production of quality waterfowl feed. Researchers in other areas have assoc-iated a decline in waterfowl populations-.with a similar change in vegetational composition (Di-Angelo, 1953; Whitman, 1973). It is clear, therefore, that the key to optima I Iy managing the unpumped habitats is through control and manipulation of the water regime. At this point it is not my intention to present a detailed plan for such an undertaking for I have neither the.teehnicaI nor the engineering background to do' so. However, a general concept of. the possibiI ities envis-aged by such a project seems in order. Basically, any successful scheme must involve interception and impoundment of the run-off from the adjacent U.B.C.Research Forest. Control of the water regime should be followed by par-252. trtioning of the area into a series of manageable units via dyke construction. These impoundments should be constructed to take advantage of existing ecological features and landforms and therefore will vary i:n size. However, impoundments ranging from 100 acres to 5-600'acres should permit a maximum range of management options. Construction of ditches and water control structures should be planned so that all impoundments can be individually manipulated as to water level and duration. As the genera I slope of this area is to the north, much of the water movement can be accomplished via gravity flow. At the outlet of this system, however, installation of a large capacity pump would be necessary to ensure year-round water control of the. entire area. . . It was demonstrated earlier in this study that waters of the agricul-tural lands were considerably more fertile than those of the unpumped areas (see Section 4.3.2). As these fertile waters are at present pumped into the Pitt River, little advantage is taken of their nutrient load. Diversion of these waters into the ditch system serving the various impoundments would permit maximum benefit to be derived from these waters. Thus, the nutrient level of these unpumped lands would be replenished via two sources (I) nut-rient rich waters from the agricultural areas and (2) rapid-oxidation of accumulated organic matter due to drawdown in the various impoundments. Additional waters for re-flooding purposes could, i f needed, be obtained from the impounded run-off waters, via the ditch system. . .Once this stage has been reached, it would only be necessary to.exper-imentally determine suitable drawdown schedules to enable maximum production of waterfowl requirements. Rotational use of the impoundments should ensure that a considerable acreage is always at, or close to, maximum productivity levels. Whitman (1973) found that within 5 to 6 years, impoundments in his 253. area were deteriorating with respect to waterfowl requirements. Therefore, he recommended drainage and subsequent re-flooding at that age to rejuvenate the impoundment. However, management should be scheduled to ensure that the bulk of the impoundments are usable at any one time. In this regard, Whitman recommended removal more than one-fifth to one-sixth of the impoundments, from production in any one year. This, then,, is. a brief, overs imp I i f.i cat ion of. what is necessary to maximize waterfowl production on these lands. Unfortunately, it may be some time before a. project of this magnitude can be fully realized. Nevertheless, there s t i l l exists immediate management opportunities in,these habitats, albeit on.a more restricted scale. The direction these efforts take will, of course, be primarily dictated by the existing water regime of the area. Thus, there would be li t t l e value in manipulating habitat to attract ground-nesting species only to have them flooded out every other year. In the case of wood duck, however, use of elevated nesting sites precludes destruction by floodwaters. However, lack of trees throughout these habitats has resulted in negligible wood duck pro-duction in the past. Similarly, past efforts'to increase production by placing artificial nests in.those trees present has resulted in only a very small portion of the available brood-rearing habitat being utilized. In similar treeless habitats elsewhere, other workers have found, that nesting boxes erected on poles were readily used by wood ducks (Grice and Rogers, 1965). .A pilot project 'involving 22 boxes fastened, to metal poles of 2" diameter was initiated during this study. The results of this project (see Table VI-23) indicate a ready acceptance of these structures. Thus, immediate initiation of a nesting. box program has a sound management basis. However, the key to success is proper..pIanning. Boxes should only be erected where suitable brood-rearing habitat is present or close by. They should also Table.VI-23: Utilization of Wood Duck Nest Boxes Placed on Metal Poles - Sturgeon Slough Marsh, 1973 and 1974 1973 1974 Tota| Boxes 22 22 No. Used by Wood Ducks 7 1 1 No. Wood Duck Eggs 57 135 No. Wood Duck Hatched 0 67 No. Boxes Used by Starlings 16 14 No. Starling Eggs Removed 79 77 No. Boxes Used by Tree Swallows 7 7 No. Boxes Used by Screech Owls 255. be p.laced with a view to minimizing time spent in checking and maintenance. Finally, anticipation: as to eventual development, i.e. impoundments and water control, is necessary to avoid large scale relocation of boxes. In cone I us ion, observance of these guidelines shouId resu11 i n a soli d breeding nucleus of wood duck in the area within five years. It follows that rapid expansion of this . popuI ation could be expected if and when the. area is fully developed. The following is a brief description as to loca-tion and number of boxes in the various unpumped habi tat .types-. These loca-tions are graphically shown in Appendix II. Open Wild Iands: -Extensive brood-rearing habitat exists' here and water is generally available throughout the brood season. At present there are no more than six mechanically sound nest boxes in the area. Erection of boxes and the suggested number involved should occur, in the following locations: OW-a) Gi I ley. Slough' - 25 boxes OW-b) the side channels flowing into Gil ley SI. and particularly the flooded sedge areas at their distal, ends -.20 boxes OW-c) the borrow-pit bordering the west side of the area - 20 boxes OW-d) the largest of the two sloughs at the north end of this habitat type - 10 boxes For brooding purposes a minimum of 40 loafing logs should be placed in con-junction with available brood cover. Sturgeon Slough Marsh and Wildlands': I). Sturgeon Slough Wildlands: Despite the general lack of open water areas, the remnants of several 256. former sloughs and channels provide opportunities that are presently unex-pIo i ted. SW-a) -3 sloughs immediately north of Koerner Road, between Rannie and Koster Roads. Includes the continuation of the most easterly slough north of the interceptor dyke - 50 boxes SW-b) a former channel of Sturgeon SI. located immed-iate I y north of the Knoll - 50 boxes SW-c) the small, slough in the extreme south end of the unpumped area - 10 boxes SW-d) the shrub swamp in the extreme north-east corner - 15 boxes .2) Sturgeon Slough Marsh: . This area, has the greatest potentia I. for producing wood duck.because of its size and cover-water dispersion. To date, erection of boxes has been limited to the main channel system. Exploitation of open water areas in the extensive bulrush stands may be difficult because,, during the peak of wood duck nest selection, very low: water levels result in these areas being temp-orarily devoid of standing water. To what extent this may discourage wood duck use is unknown.. Nevertheless, late and re-nesfers would have little trouble in. exploiting such boxes. To facilitate checking, erection of boxes should, for the time being, be restricted to-channel banks in most instances. However, one area, per-haps Hobbs (SM-a), should be used as an experimental site for placement of boxes away from channel banks. To increase the utilization of the northerly reaches of the marsh'(SM-b) boxes should be erected along the borrow-pit between this marsh and the adjacent Public Shooting Marsh. At present, use 257. of .this area seems to be highly favoured by wood duck, probably because of the adjacent tree cover along the dyke. Many of these overhang to the water, thus providing apparently attractive cover. The continuation of the borrow-pit as a channel (SM-c) .along the north-east side of the marsh appears to be another highly suitable area that, at present, appears virtually unused by breeding wood duck. It should be stressed that any program to increase wood duck production in this marsh must be accompanied by the provision of loafing and brooding sites. These will not only provide brooding stations but also enhance the value of the marsh as a moulting area. Public Shooting Marsh: Assuming that food, ava i labi I ity i.s adequate (see Section 5.2. I) this area should produce a large number of wood ducks, if nesting sites are pro-vided. However, as in the Sturgeon Slough Marsh, the orderly placement of boxes, rather than helter-skelter distribution, would be preferable. A number•of -potentiaI sites are listed as follows: PSM-a) the channel-side of the spit at the south end of the marsh PSM-b) the ponds created by borrowing f i l l for dyke construction along the south-western edge of the marsh PSM-c) the entire eastern edge of the marsh bordering the mounta in -PSM-d) along the banks of the main channel, starting at the south end. Side-channels could also be used as they are encountered 258. PSM-e). use of the other than the areas mentioned should probably be restricted to the northern portion.. This will ensure easy access via canoe, thus limiting expenditure of'time in checking and maintenance. In addition, under the existing water regime, the southern portion of the marsh is often dry during the nest selection period. Placement of boxes at the north end should take advantage of the "edge" created by the clumped nature of bulrush stands. To this point, emphasis on immediate waterfowl management in the unpumped lands has been directed at the wood duck because of its generally flood-proof nesting habits. Recent experimental work, in North Dakota (Doty at a I., 1973), however, has shown that ground-nesting species such as mallards can also be induced to use elevated nesting structures. Thus, if the f u l l -scale development that would provide secure sites for ground-nesters is found to be some years away, a program similar to that in North Dakota may be feasible here. One modification would be to substitute mallard eggs in occupied wood duck nests. In this manner, the mallard duckIings. wouId be imprinted on elevated nest structure. Thus., females returning to their natal marsh the following spring should readily accept such nesting sites. In conclusion, implementation of the immediate management opportunities suggested should result, in a noticeable increase- in spring and summer waterfowl use of the unpumped areas within a few years.. But, such a program will fail to achieve its potential if not administered properly! This is forcefully brought home by considering the past.and present status of such projects in and adjacent to the study area. Large numbers of boxes have been 259. erected and maintained for a year, then abandoned' in successive years to starlings and the elements as the novelty of the project wore off. Boxes have been placed in trees simply because the latter were there, with little consideration for post-hatching needs of the broods. Though most groups and individuals keep some sort of record.on the status and use of their boxes there appears to. be little uniformity in the recording of data. Li ttIe. effort is made to band and/or mark wood ducks despite the relative ease of catching incubating females, flightless young and flying birds in fall and winter concentrations. Thus, we have little knowledge as to the mortality, return of locally raised females to nest, or the ultimate dis-tribution of birds raised from these projects. In short, we have yet to advance from the stage of wood duck propagation to wood duck management - and there is a very real difference between the two. Some improvement in this direction may occur with the recent, though belated, efforts .of the Fish and Wildlife Branch to co-ordinate data col-lection locally. However, Iwould suggest that the formation of a Wood Duck Management Authority, or Committee for the entire Lower Fraser Valley is the ultimate answer to the problem. Ideally, this group should combine the technical experience of the professional with the practical, experience of the layman. It should, however, consist of as few individuals as will permit, rapid and sound decisions with a minimum of bureaucracy. Once such an Authority is formed, all existing and future wood duck management projects should come under its jurisdiction. On Iy then' wU I the full potential of the Pitt and Fraser Valleys as suitable wood duck habitat, be realized. A final consideration in the present and future management of waterfowl in the unpumped habitats concerns the effect of unrestricted hunting on both local breeders and migrants. In the case of breeders, there is increasing 260. evi dence. e I sewhere in North America .that heavy., early season gunning on marshes supporting a local nesting population can result in that population .becoming non-viable over a period of years. This situation,, or "burn out" as it is referred to, arises because local adult hens and young of the year tend to dally in the natal marsh well into the f a l l , weather permitting (Hochbaum, 1944)., Thus, this component of the local breeding population often bears the brunt of early season hunting pressure. The end result, is that such pressure can eventually reduce or eliminate the local females, thus removing that segment of. a breeding population that is innately drawn back to its natal marsh year after year. Based on the banding results from this, study, it appears that most of the annual harvest of local ma I lards and aduit wood ducks occurs within the study area (see Section 6.2.6). . Thus, one of the two requirements, leading to "burn out" already exists in the Pitt Valley. The status of the second requirement, hunting pressure, has not yet been clearly defined. The shooting rights to over 3,000 of the approximately -3,600 acres of unpumped habitat are currently held by a gun club, with the remainder open to the general hunting public. Considering the respective levels of hunting pressure now existing in these two areas (see Table V.I-13), it is obvious that pressure exerted on local waterfowl on the club marshes is but a fraction of that occurring on public lands.. In effect then, the controlled hunting (see Section 6.2.7) occurring in the club marshes may be acting as a buffer to "burn out" in the study area. Under the present lease agreement (Laseur, 1974)- the gun club has the shoot i ng-'rights on the 3,000" acres until the conclusion of the 1977-78 hunt-ing season. At that time, administration of hunting will fall under the jurisdiction of the government agency responsible for these Crown lands. 261 . This will undoubtedly be followed by a clamour by the hunting public for unrestricted access to these lands. It is strongly recommended that such access be denied and that the area be subject to controlled hunting only. One has only to look at the effect that uncontroI Ied hunting practices have had on waterfowl use of •the Public Shooting Marsh (see Section 6.3.7) to realize the potential impact on both breeding and migrant waterfowl use. of the Pitt Valley if such practices are extended to the Sturgeon Slough Marsh. The type of controls imposed will depend to some extent on what form the proposed development of the 3,000 acres takes. Nevertheless, it is possible to suggest at this stage that I imits on the number of hunters at any one time, the number of shells per hunter, and the number of days of hunting per week are bare minimum requirements. Provision of fixed- blinds and decoys, at a minimal fee, and insistence of at least one dog per party, are further refinements that would greatly improve the overall hunting experience for the participants. Eventual public acceptance of controlled hunting in the area could be greatly enhanced if such a practice was immediately instituted in the •Public Shooting Marsh. As it presently exists, hunting in this marsh is , an indictment of consumptive use in generaland of past management efforts in particular. A continuation of such practices will do. as much to elimi-nate hunting as a recreational pursuit in this area as will any reaction • on the part of the waterfowl resource. 262. 7.0.0 SUMMARY I.. Severe annua I . f I ooding by oligotrophia waters occurs seasonally on the unpumped acreage of the study area. On the acreage with the water table controlled by pumping, seasonal, flooding is , infrequent and of short duration. The waters of this area are . relatively eutrophic, reflecting the development of reclaimed lands for agricultural purposes. 2. Permanently waterlogged soils in the unpumped areas contain more calcium.and magnesiurn and less organic matter than do adjacent seasonally flooded soils. Reduction in flooding,.and. restructuring of the soil profile by ploughing results in a marked stratification and accumulation of potassium, calcium and magnesium on managed . , lands of the pumped acreage.. 3. Twenty-two non-forest communities were identified and delineated on a vegetation cover-map. Dry matter yeiIds of selected communi-ties .i ncreased .a long a hydr ic-metr ic gradient whereas the protein apparently decreased. Selected communities generally exhibited a greater protein percentage when growing in pumped rather than unpumped areas. 4.. Based on three fractions of plant origin present, i.e. new growth, old growth and duff, terrestrial communities tend to "tie-up" more nitrogen per unit area' during the growing season than do emergent 263. emergent communities. I n . particuIar, hardhack communities in both pumped and. unpumped areas appear to be an important source of'.' nutrient "short-stopping" in the study area. 5. Temporal and spatial changes in water regime, since dyking in the first decade of this century, has accelerated the community succession in the area.. Rapid "mat-formation" on ponds, sloughs and ditches of the unpumped areas in the last 24. years has not-iceably reduced the surface area of these waterbodies.. Continua-tion of this trend will soon result in the "loss" of all but the deeper, portions of marsh to shrub swamp and, eventually,.bqg. 6. A comparison of the numbers and yields of twelve aquatic inverte-brate, families and waterfowl brood production in three habitat types suggested that a)some factor(s) other than a source of invertebrate food for young ducklings is responsible for the relatively low brood production in.Ag. II and b) the invertebrate food base may play a role in the low brood production on the •. Sturgeon Slough Marsh. 7. The major nesting species of waterfowl are mallard, wood duck and cinnamon tea I. The nesting period of.mallard and cinnamon teal in the unpumped habitats coincides with rapidly rising water levels in these areas. Prevention, or flooding, of first nests and e I imi nation of by flood waters appears to be the . major factor limiting waterfowl production in these habitats. 264. 8. .In.1973 total brood production in the study area was calculated to be 8.3 broods/sq. mile. A total of 519 young of the three major nesting species were calculated to have reached the flight stage., Production in .1972 was judged to have been slightly lower due to spr i ng fIood i ng. . 9. Thirteen sightings of potential mammalian predators, consisting of five species, were made and on two occasions mammalian predation was witnessed. Nine of eleven cases-of potential predation en-countered were attributed to avian causes. . Ease of travel, pre-ponderance of artificial and natural "traveI -1anes" and a probable greater abundance of the overall prey base in the agricultural hab itats may • res.u It in greater predator activity in these areas. 10. The Sturgeon Slough Marsh, and probably the Public Shooting Marsh, are used extensively by moulting mallard and wood duck. The presence of more adult ducks than breeders during the moulting period in the study area supports the' view that there is an influx of. birds from elsewhere. 11. Based on banding done during the study most locally raised mallards harvested are taken in, or adjacent to, their natal area within the first eight days of hunting. Adult wood ducks appear to be essentially non-migratory and receive IittIe hunting pressure after the first two weeks of the hunting season. During November, most immature wood ducks migrate to the WiMammette Valley of Oregon and the Central VaI leys of California. Approximately two-thirds of the harvest occurs in these areas with'the remainder occurring in the latter part of October on, or adjacent to, the study area. Less than 10$ of the land area of the Pitt Valley is open to public hunting, resulting in disportionate hunting pressure and success on club and non-club lands. Hunting success over the entire 1973 waterfowl season ranged from a high of 3.90 ducks/hunter-day on some club lands to a low of .34 ducks/hunter-day in the Public Shooting Marsh. Mallard, pintaiI, widgeon and green-winged teal constitute the bulk of the waterfowl harvest in the Pitt Valley. Management opportunities to enhance waterfowl use in Ag. I, Ag. II and Dense Wildlands are limited by designation of these lands for intensive agriculture. Control and regulation of the water regime in the Open Wildlands, Sturgeon Slough Marsh and Public Shooting Marsh must be realized'before the productivity of these habitats can be increased. Until, effective control of water levels is realized, immediate management opportunities in the unpumped habitats should be limited to estabI ishing a viable wood duck population. LITERATURE CITED ALEXANDER, M.M. 1959. The Habitat Map: A Basis for Wildlife Management. N.Y. Fish & Game Jour. 6(I):I 03-I I 3. BARTONEK, J.C. and J.S. HICKEY, |969. Food Habits of Canvasbacks, Redheads and Lesser Scaup in Manitoba. The Condor 71:280-290. BARTONEK, J.C. 1972. Summer Foods of American Widgeon, Mallards and a . 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Jour, of Botany 49:I 177-1199. WESTLAKE, D.F. 1965. Some Basic Data for Investigations of the Pro-ductivity of Aquatic Macrophytes. Mem, Ist. Ital. Idrobiol. 18 Suppl.:229-248. WHEELER, R.J. 1966. Duck Nesting and Production in the Humboldt Bay Area. M.Sc. Thesis,'HumboIdt State College. 58 pp.-WHITMAN, W.R. 1973. A Preliminary Report of Ecological Changes with Impoundment in the Tintamare National Wildlife Area and Missaquash Marsh. Paper given at Waterfowl Habitat Management Symposium, July 30 - Aug. I, 1973. Moncton, New Brunswick. WILKINSON, A.T.S. and H.R. MACCARTHY. 1967. The Marsh Crane Fly (T.ipula  pa Iudosa Mg.), A New Pest in British Columbia, (Diptera: Tipulidae). . J. Entom. Soc. of B.C. 64:29-34. Climate of British Co Iumbia - Tables of Temperature, Precipitation and .•Sunshine, 1965-1971. MeteroIogicaI Branch, Dept. of Transport, Canada. 275. APPENDICES 276. APPENDIX I (See map in the pouch at back) APPENDIX 2 277 S a l i x spp.-S. d o u g l a s i i -S. microcarpus DIAGRAM I T. l a t i f o l i a - C. r o s t r a t a - Eleo-charis sp. S. acutus non-vegetated pH 5.0 5.2 - 4.7 4.8 %0.M. 3.15 3.71 4.07 3.45 % N. .16 • • .16 .22 .15 1 K - 35.00 23.75 92.50 102.50 6 Ca. .313.00 513.00 550.00 488.00 &Mg. 101.25 187.50 127.50 80.00 11.9 6.5 4.0 3.4 acutus DIAGRAM 2 4.7 2.92 .15 61.25 425.00 247.50 1.5 / Myriophyllum sp. I 5.5 1.35 .058 63.75 675.00 211.25 2.0 normally submerged mud bar 6.1 .92 .036 52.50 725.00 292.50 2.3 278 DIAGRAM 3 C. canadensis S. d o u g l a s i i 1 . C. canadensis ty \ E. canadensis \\(//\ non-vegeta-ted pH % O.M. % N. I K-a, Mg. .1 P-4.7. 8.97 .48 55.00 88.00 63.75 11.00 4.7 11.93 .62 91.25 63.00 67.50 20.10 4.8 6.73 .33 63.75 100.00 68.75 16.4 4.8 1.20 .052 22.50 488.00 125.00 2.4 5.1 1.50 .087 25.00 463.00 87.50 2.6 DIAGRAM 4 pH % O.M. % N. K | Ca. e M 8 -a. p 4.8 5.53 .31 48.75 763.0 125.0 9.0 5.1 15.21 .73 116.25 1371.0 300.0 12.7 5.2 15.31 .75 125.00 1513.0 305.0 12.4 5.1 14.73 .68 71.25 1500.0 382.50 8.0 279 S. microcarpus and G. rostrata DIAGRAM 5 C. candensis and C. rostrata E. canadensis non-vegeta-tive pH % O.M. % N. I K. Ca. Mg. P. e a. 4.8 7.33 .40 60.00 175.00 88.75 29.6 4.8 8.65 .19 28.75 213.00 67.50 19.4 4.8 3.02 .13 41.25' 488.00 133.75 3.0 5.0 5.29 .27 48.75 825.00 171". 25 3.5 APPENDIX 3 280. NUMBERS AND DISTRIBUTION OF AQUATIC INVERTEBRATE FAMILIES USING A DIP NET SAMPLER - 1972 Sturgeon Public No. Samples: DIPTERA Ghironomidae Ephydridae Tipulidae Chaoboridae Ceratopogonidae Staphylinidae Dixidae Culicidae Sciomizidae Nematocera Agric. I (12) 2 1 1 1 Agric, II (8) 20 12 Open Wildland ~ ~ ( 9 ) 30 2 4 1 1 Dense Wildland (6) Slough Marsh (11) 2 1 Shooting Marsh HEMIPTERA Corixidae Nalsidae Notonectidae Gerridae Mesoveliidae Saldidae Miridae Veliidae 14 40 22 1 36 9 1 10 12 10 13 7 34 21 H0M0PTERA Aphidae Cercopidae Cicadellidae COLEOPTERA Hydrophilidae Dytiscidae Haliplidae Gyrinidae Chrysomelidae Cocinellidae Cavabidae Curculionidae Unidentified (mangled) 3 3 2 1 1 CRUSTACEA Talitridae Daphnidae Asellidae Chydoridae Cyclopidae Unidentified 123 208 3 1 24 22 1 14 54 Appendix 3, page 2 Agric. I Agric, . II Open Wildland Dense Wildland Sturgeon Slough Marsh Public Shooting Marsh GASTROPODA Lymnaeidae Planorbidae Ancylidae Physidae Sphaeridae Unidentified 5 29 1 6 1 11 36 6 2 •1 1 11 16 8 4 2 19 20 9 5 13 104 7 27 5 ODONATA Coenagrionidae Libellulidae Aeschnidae COLLEMBOLA Isotomidae TRICHOPTERA Psychomyidae Hydrotilidae Unidentified EPHEMEROPTERA Baetidae LEPIDOPTERA Unidentified NEMATODA Unidentified ARANEIDAE Araneae ACARINA 1 1 Unidentified HYMENOPTERA Appendix 3, page 3 Sturgeon P u b l i c A g r i c . A g r i c . Open Dense Slough Shooting I I I Wildland Wildland Marsh Marsh NEUROPTERA S i a l i d a e - - - - _ _ U n i d e n t i f i e d - - - - - -. MONOPISTHOCOTYLEA U n i d e n t i f i e d - -ANNELIDA Lumbriculidae - - - - - -UNIDENTIFIED - - - - 2 NUMBER OF FAMILIES 27 21 26 18 .17 15 NUMBER OF ORGANISMS 516 123 191 102 221 112 NUMBER OF ORGANISMS PER SAMPLE 43.0 15.4 21.2 17.0 19.0 16.0 283 APPENDIX 4 Numbers and D i s t r i b u t i o n of Aquatic Invertebrate Families Using a Stovepipe Sampler - 1972 No. Samples: DIPTERA Chironomidae Ephydridae Tipulidae Chaoboridae Ceratopogonidae Staphalinidae Dixidae C u l i c i d a e Sciomizidae Nematocae Agric, I " 0 2 T 13 Agric. II 16 1 1 Open Wildland (9) 14 1 1 2 Dense Wildland (6) Sturgeon Slough Marsh 9 1 Public Shooting Marsh HEMIPTERA Corixidae Nalsidae Notonectidae Gerridae Mesoveliidae Saldidae Miridae V e l i i d a e 1 3 1 1 1 HOMOPTERA Aphidae Cercopidae C i c a d e l l i d a e 1 1 COLEOPTERA Hydrophiliidae Dytiscidae H a l i p l i d a e Gyrinidae Chrysomelidae Co c i n e l l i d a e Cavabidae Curculionidae Unidentified (mangled) 1 4 2 4 Appendix 4, page 2 COLLEMBOLA Isotomidae TRICHOPTERA Psychomyidae Hydrotilidae U n i d e n t i f i e d EPHEMEROPTERA Baetidae LEPIDOPTERA Uni d e n t i f i e d NEMATODA Unidentified ARANEIDAE Agric. I Agric. II Open Wildland Dense Wildland Sturgeon Slough Marsh Public Shooting Marsh CRUSTACEA T a l i t r i d a e Daphnidae A s e l l i d a e Chydoridae Cyclopidae U n i d e n t i f i e d 88 1 1 1 2 1 21 42 2 15 GASTROPODA Lymnaeidae Planorbidae Ancylidae Physidae Sphaeridae Un i d e n t i f i e d 1 6 9 2 1 2 2 1 12 1 14 1 21 13 9 ODONATA Coenagrionidae L i b e l l u l i d a e Aeschnidae 3 1 22 Araneae Appendix 4, page 3 Sturgeon P u b l i c A g r i c . A g r i c . Open Dense Slough Shooting I I I Wildland Wildland Marsh Marsh ACARINA U n i d e n t i f i e d HYMENOPTERA Ant NEUROPTERA S i a l i d a e U n i d e n t i f i e d MONOPISTHOCOTYLEA U n i d e n t i f i e d ANNELIDA Lumbriculidae UNIDENTIFIED (mutilated) NUMBER OF FAMILIES NUMBER OF ORGANISMS NUMBER OF ORGANISMS PER SAMPLE NUMBER OF ORGANISMS/ft 3 4 1 21 147 19 47 16 55 12.3 5.9 6.1 32.9 26.4 11.6 1 13 17 74 136 12.3 33.5 12.4 19.6 7 10 1.4 3.51 APPENDIX 5 NUMBERS AND DISTRIBUTION OF AQUATIC INVERTEBRATE FAMILIES IN SELECTED HABITATS - 1973 No. Samples: DIPTERA Chironomidae Ephydridae Tipulidae Chaoboridae Ceratopogonidae Dolichopodidae Dixidae Cul i c i d a e Scatophagidae Empidae Chloropidae Sciomizidae Simulidae Agric. I "750) 77 16 3 1 1 9 1 2 Agric. II ~ 7 2 8 ) 54 2 7 6 4 3 33 1 1 Sturgeon Slough Marsh (75) 153 7 3 1 1 1 1 1 1 HEMIPTERA Corixidae Nalsidae Notonectidae Gerridae Mesoveliidae Saldidae Herbidae V e l i i d a e Macroveliidae Hydrometridae 52 18 33 12 50 44 3 7 1 1 40 34 HOMOPTERA Aphidae Cercopidae C i c a d e l l i d a e 4 96 COLEOPTERA Hydrophilidae Dytiscidae H a l i p l i d a e Gyrinidae Chrysomelidae •Cocinellidae Cavabidae Curculionidae Dryopidae Hydraenidae Amphizoidae Other 37 46 4 1 1 2 25 10 1 2 6 1 2 2 2 3 41 Appendix 5, page 2 Sturgeon Agric. I Agric. II Slough Marsh CRUSTACEA Talitridae 97 20 27 Daphnidae 1 - 1 Asellidae - - -Chydoridae 42 Cyclopidae - -. Unidentified - -GASTROPODA Lymnaeidae 15 7 , 5 8 Planorbidae 90 43 19 Ancylidae . 3 14 2 Physidae 90 67 1 Sphaeridae 1 1 -Unidentified - , -ODONATA. Coenagrionidae 48 63 81 Libelludlidae .2 1 Aeschnidae 1 - -COLLEMBOLA Isotomidae 2 1 -Smynthuridae 201 - 6 TRICHOPTERA Psychomyidae - - -Hydrotilidae - - -Unidentified - - ~ EPHEMEROPTERA Bactidae 5 - 5 Caenidae 27 10 LEPIDOPTERA Unidentifed - - -NEMATODA Unidentified _ _ ARANEIDAE Araneae 7 2 19 ACARINA Hydrocarina 1 7 Appendix 5, page 3 Agric. I Agric. II Sturgeon Slough Marsh HYMENOPTERA Ant Dacnusa 1 .3 6 NEUROPTERA . . . Si a l i d a e _ . _ Unidentified - -MONOPISTHOCOTYLEA Unidentified - -ANNELIDA Lumbriculidae - -UNIDENTIFIED (Other) 21 11 21 NUMBER OF FAMILIES 39 35 36 NUMBER OF ORGANISMS 969 499 637 NUMBER OF ORGANISMS PER SAMPLE 19.3 24.9 8.2 I I P ! I Ml ml imp* 15 ?3C IS S3 i f J fe^" i i si ^ 2— c&see-ve.^ APPENDIX 7 Plumage Development of Pen-raised Wood Ducklings Other workers (Grice and Rogers, 1965) have suggested methods, based on size, shape and/or plumage development, for aging immature wood ducks in the f i e l d . These do not, however, provide sufficient categorization of the f i r s t twenty days of development compared to the method developed for other species by Gollop and Marshall (1954). To provide some continuity with the data being generated for other species in the study area, i t was deemed necessary to establish a simi-lar method for wood duck. A total of thirteen wood ducklings were obtained at hatching and raised in confinement to the flying stage. For the f i r s t 31 days of this period each bird was weighed and i t s plumage development noted every 3 to 5 days. Based on the results obtained, the following charts were developed and used during the 1973 brood season. Table 1: Plumage Development of Pen-raised Wood Ducks Plumage Sub Class Class I a Bright b a l l of f l u f f . Down bright, patterns distinct. Body rounded; neck and t a i l not prominent. Downy Young b Fading b a l l of f l u f f . Down colour fading, patterns less distinct. T a i l development obvious, gives body a slightly elongated appearance. c Gawky-downy. Down colour and patterns faded. Body elongated; t a i l very prominent but s t i l l capped with down. Neck prominent. II a Fi r s t feathers. Fir s t feathers show on side p a r t ^ and above wing, primaries not visible. Face • r- ' t , pattern on males barely visible, feathered r J 291. Table 2: Approximate Midpoint Age (in days) of Each Subclass and Supplementary Data for Wood Duck ' Plumage Classification la lb i£ Ha Supp. Data 4 11 20 28 Metallic-green of gtr. secondary coverts shows as shiny patch at a dis-tance between Ha and l i b The charts were not extended beyond age Class Ha due to exper-imental error. Nevertheless, this yielded sufficient data to permit construction of hatching curves and provided an indication of losses during the period of high mortality in waterfowl broods. Because of the controlled conditions in which the birds were raised and examined the data collected must be considered only an approxi-mation of that obtainable under "wild" or f i e l d conditions. It is f e l t however, that the error involved is sufficiently small as to justify use of the above classification in this study. The charts were not extended beyond age Class Ha due to experimental error. 292. APPENDIX 27 • September'1973 Mr. E.G. Hunt, Chief, Wildlife Management, Department of Fish & Game, The Resources Agency, Dear S i r , I am conducting a research project into the low waterfowl productivity of the wetlands of the P i t t River Valley, approximately 40 miles east of Vancouver, B.C. One hypothesis proposed was that the original breeding population lias been 'Tjurnt out" by overliunting. To test this we conducted an extensive banding operatmnn this summer and i n addliticn to banding a l l birds caught, we used a nasal saddle of the type described by Sugden and Poston in the J. Uldlf. Mgmt. 32:4, a copy of which I am enclosing. We used a red market on Mallards, a yellow one on Wood Duck and white on Cinnamon Teal. Each tag has a number on one side and a "M", "W" or "C" on the other,, depending on species. In seme of our earlier efforts we were forced to use an inferior paint which by net; may make the number i l l e g i b l e . Nevertheless, just the sighting of one of the aforementioned species with a nasal marker w i l l allow us to gain an insight into migrational movements of the local birds. Therefore, i f you receive any reports from f i e l d personnel, bird watchers, etc. of WaterfowD, marked as described, I would greatly appreciate hearing about i t . Heedless to say, the area and circumstances of the sighting are essentially what I'm after. I f i t ' s also possible to read the number, then I w i l l be able to trace the bird to the'site of marking. Your cooperation i n this natter would be appreciated. Yours sincerely, Tony Barnard Graduate Studies AEBrlmg K A T c R R M . HARVEST RECORD for ) LocatiG., | Hunted 1 Ho, I Hunters Ho, | Dons { 1 j j 1 9 7 _ Hatarfowl.f C r i s p ; e n ! Los t j S peeler; Breakdown j. j ^ - ™ .-..A. -f I . . _ , „ .-4.*...—«.*™-f " ~ " " ~ - ' ""'^ _„,... ^ _ . _ f — : ! i t •. ! L„. : • - • ^ — — ! i L, ., I 1 i r : ~ i " 3 j _ APPENDIX 10 294. THE UNIVERSITY OF BRITISH COLUMBIA VANCOUVER 8, CANADA DEPARTMENT OF PLANT SCIENCE AGRONOMY, HORTICULTURE, CROP PROTECTION Dear I am currently involved in a waterfowl research project i n the P i t t Polder area of the Lower Fraser Valley. One aspect of the study is to get a J irm idea of the productivity of the area with respect to the hunting of waterfowl. This year we hope to e l i c i t the voluntary cooperation of hunters in helping us to determine the quality and quantity of hunting i n the Polder area. In 'this regard I understand that you made a number of trips to the Pitt Polder area to hunt waterfowl last year. Would you be interested in assisting us in properly managing the waterfowl resource in the P i t t Area? This can be accomplished i f you would consent to f i l l out a simple form after each hunting t r i p , whether you bagged birds or not. If you are interested i n participating in this project during the 1 9 7 3 - 7 4 waterfowl season please check the appropriate box below and return this to me using the enclosed envelope. As the season is only one month away i t would be appreciated i f you could indicate your interest as soon as possible so "that I can supply you with the necessary forms prior to the season opening. Yours sincerely, A.E. Barnard Graduate Studies Plant Science AEB:lmg I am interested i n participating I am not interested i n participating 295 THE UNIVERSITY OF BRITISH COLUMBIA V A N C O U V E R 8 , C A N A D A P K P A R T M K N T O F P L A N T S C I E N C K A O K O N O M Y , IIOH11CUI.TURR. C H O P PPDTr.aiON Dear Thank you for your prompt reply and expression of interest in the waterfowl resource of the P i t t Valley. Enclosed you val1 find 5 data sheets on which to record the results of your hunting trips in the P i t t area this f a l l ard winter. In addition, I have enclosed 3 maps of the area. As you can see, the map is broken into sub-areas, based mainly on the boundaries of the various private and public shooting areas. Basically then, I would appreciate i t i f you ecuId f i l l out one entry for every hunting t r i p you make, whether i t is for a few hours or a whole day~ T T you do not bag any birds, i t is important that you s t i l l record that a t r i p was made.' This w i l l permit me to estimate the average hunter success in the sub-areas a n d the P i t t Valley as a whole. To ensure that there is a basic uniformity in the recording of data by those participating in this program, I would - like to. briefly run. through the procedure of f i l l i n g out the waterfowl harvest record. The date i s of cour.-i-. self-explanatory. In the "Location Hunted" column, could you insert the numbe:-on your map.that corresponds to the area in which you hunted, i.e. i f you hunted i n the Public Shooting Area then you would enter ( T ) in the "Location Hunted" column. If you hunted in an area on the map not marked with a'name and number, mark this on one of the spare maps arid mall~it to me so that I car: add such a sub-area to the present l i s t . The "No. Hunters" column w i l l permit you to record the number of hunters in your party on those days that ycu don't: hunt alone. In the latter case, of course, you would enter "1". The "No. Dog:-." . i s self-explanatory. "Waterfowl Bagged" w i l l be the number of birds taken per t r i p by each hunter in the- party,1 i.e. i f by yourself then enter 1, 2, 3 , . . up to 8; i f with others enter what - each hunter bagged separately, e.g. 3 duck:-;, 7 ducks, for. a'total of 10 ducks by 2 hunters. "Waterfowl" pertains to a l l waterfowl that you shoot at .and knock down b i t do not retrieve. The data in this column, in conjunction with that in the "No. Dogs" column w i l l give us' an idea as to the value of dogs in reducing crippling loss in the Pitt-Valley area. The "Species Breakdown" colum i s very important. Here, I would appreciate i t i f you-would break, down the'number 6T waterfowl in the "Waterfowl Bagged" column into the respective species, i.e. Waterfowl . Waterfowl Bagged Cripples 8 Species Breakdown H mallards, 2 widgeon 2 green-winged Teal • • • » /I 296 ..../? Enclosed ycu w i l l find a booklet that may aid you in identifying the less ccmmon species of waterfowl. If you are s t i l l unsure of the. identity of a bird or birds, then remove one wing as close to the body as possible and either air-dry i t or freeze i t . If you then contact me, I w i l l be glad to drop by and identify i t . Finally, we have provided a small space'for any comments that you feel might add to our knowledge of the vaterfowl resource i n the P i t t area based on a given day's hunt. These could include estimates of the total ducks seen and the species composition, the number of hunters in your v i c i n i t y , peak periods of waterfowl ac t i v i t y (time of day), weather conditions, etc. If the space provided i s insufficient, feel free to write on the back of the sheets, but please be sure to date each comment(s). At f i r s t glance, these instructions seem to indicate a large amount of work i s necessary to record the data. However, I feel sure that a given day's information can be recorded in 2-3 minutes, providing you f i l l out the form 'immediately after returning from the hunt. I can assure you from personal experience that nothing fades so fast as one's memory, and, needless to say, the information I derive w i l l only be as accurate as the data that is submitted. If ycu have any problems regarding this project, please do not hesitate to contact me by writing to the above address or calling me at 228-4384 or1 531-2329. Once again, I'd like to thank you for your cooperation, and w i l l be glad to provide you with a copy of the results when they are tabulated. Good luck and good hunting! . Yours sincerely, Tony Barnard Graduate Studies, Plant Science AEB:lmg WUERPCWL HARVEST RECORD f c r , 197 Date Lccaticn Msrrted No. Banters No. Dogs VJaterfowl Bagged Waterfowl Cripples Lost Species Breakdown Carmen ts Name (please print): ro -3 298. DUCKS AT A DISTANCE - a waterfowl i d e n t i f i c a t i o n guide . (See pocket at back) APPENDIX 11 AGE AND SPECIES COMPOSITION OF  WATERFOWL HARVEST - p c t. 7 . 1972 - PITT POLDER AREA ADULT IMMATURE Species cr 9 % c r 9 % Total % Mallard 7 19 34.0 22 28 66.0 76 34.3 Pint a i l - - - 9 14 100.0 23 10.4 A, Widgeon - - - 13 8 100.0 21 9.5 G.W. Teal 1 4 7.6 29 31 92.4 65 29.4 B.W, Teal/Cin.Teal - - - -' 2 100.0 2 1.0 Wood Duck 5 2 38.8 6 5 61.2 18 8.1 Gadwall - - • - 3 - 100.0 3 1.3 Shoveler - - 2 2 100.0 4 1.8 Hooded Merganser - - - 1 3 100.0 4 1.8 Ruddy Duck - - - 2 2 100.0 4 1.8 Ring-necked Duck - - - - 1 100.0 1 .5 Mallard X • - - - - 1 100.0 1 .5 TOTAL 13 25 17.3 87 97 82.7 222* 100.0 (167)** * includes Sturgeon Slough Game Club members ** does not include Sturgeon Slough Game Club members AGE AND SPECIES COMPOSITION OF  WATERFOWL HARVEST - Oct. 6, 1973 - PITT FOLDER AREA Al )ULT IMMATURE Species 9 eri /o 'd* 9 % Total % Mallard 4 24 - 15 3 • - 46 26.5 Pintail - 2 7.0 14 12 93.0 28 16.1 A. Widgeon - - - 10 12 100.0 22 12.6 G.W. Teal - 2 5.7 18 15 94.3 35 20.1 B.W./Cin. Teal - - - 1 2 100.0 3 •1.7 Wood Duck 5 5 77.0 1 2 23.0 13 7.5 . Shoveler - - • - 5 6 100.0 11 6.3 Hooded Merganser 1 1 28.5 5 - 71.5 7 4.0 Ring-necked Duck 1 2 43.0 2 2 57.0 7 4.0 Gtr. Scaup - 1 100.0 - - - 1 • 6 Bufflehead - 1 100.0 - - • - • 1 .6 TOTAL 11 38* - 71 54* - 174 100.0 * not correct due to mallard components APPENDIX 12 AGE, SPECIES AND SEX COMPOSITION OF  WATERFOWL HARVEST - PITT MEADOWS AREA, 1972 - submitted in 1972-73 National Wing Survey ADULTS JUVENILES Species <? 9 % u/d d7 9 % j/d Total % Mallard 4 6 25.5 1 14 15 74.5 - 40 39.6 Pintail - - - - 7 7 100.0 - 14 13.8 A. Widgeon 1 - 6.0 - 5 11 94.0 - 17 16.8 G.W. Teal 1 5.0 1 11 8 95.0 1 22 21.8 Wood Duck - - - - 1 -' 100.0 1 1.0 Shoveler - - - •- 1 1 100.0 1 3 3.0 Amer. Merganser - - - - - - - 1 . 1 1.0 Ruddy Duck - - - 1 - - - - 1 1.0 Ring-necked Duck - - - - ' - - - 1 1 1.0. Redhead 1 - 100.0 - - - - - 1 1.0 TOTAL 6 7 3 39 42 86.0 4 101 100.0 AGE, SPECIES AND SEX COMPOSITION OF WATERFOWL HARVEST - PITT MEADOWS AREA, 1973-74 - submitted i n 1973-74 National Wing Survey ADULTS IMMATURE : Species 9 % u/d cr~ ? % u/d Total % Mallard 3 l 10.0 - 19 17 90.0 1 41 27.0 Pint a i l - - '- 13 9 100.0 - 22 14.5 A. Widgeon 1 - 3.0 - 13 17 97.0 - 31 20.4 G.W. Teal 1 l 5.0 - 21 15 95.0 1 39 25.6 Wood Duck 1 l 50.0 - • 1 1 50.0 - 4 2.5 Shoveler - - - • - 1 2 100.0 •- 3 2.0 Gadwa11 .1. - 14.0 - 3 3 86.0 -. 7 3.2 H. Merg. - - - - - 100.0 1 1 .7 Ring-necked Duck 1 - 100.0 - - - - 1 .7 Barrow's Goldeneye - - - - - 100.0 3 3 2.0 Canvasback - - - - 1 - 100.0 -. 1 .7 Bufflehead - .- '- - - - 100.0 1 1 .7 TOTAL 8 3 7.3 - 7 2 64 92.8 7 .154. 100.0 304. APPENDIX 13 PARTIAL CHECK LIST, HIGHER PLANTS, 1973  PITT POLDER, PITT MEADOWS, B.C. Lycopodiacea Lycopodium annatinum L . Isoetaceae Isoetes n u t t a l l i i A. Br. Equisetaceae Equisetum palustre L. Equisetum pratense L. Equisetum arvense L. - Sturgeon Slough, Pitt Meadows, B.C. Jn. 4/73 Equisetum (fluvrotile?) Polypodiaceae Cryptogramma crispa (L.) R. Gr. • Dryopteris austriaca (Jacq.) Woynar Blechnum spicant (L.) Roth. Aug. 5/73. Pottinger Bog, Pitt Meadows, B.C. Athyrium f elix - femina L. Spiraea - Sphagnum Pteridium aquilinum (L.) Kuhn Polystichum munifum (Kaulf.). Presl. Polystichum lonchitis (L.) Roth. Athyrium filix-femina (L. ) Roth. Woodsia oregana D.C. Eat. Cupressaceae Thuja plicata Donn. May 30/73 Pinaceae Tusga heterophylla (Raf.) Sarg. Pitt Meadows, B.C. Jn. 4/73 Picea sitchensis (Bong.) Carr. Pitt Meadows, B.C. Jn. 4/73 Pseudotsuga menziesii (Mirb.) Franco Pitt Meadows, B.C. Pinus contorta Dougl. P i t t Meadows, B.C. Jn. 4/73 Pinus monticola Dougl. Pitt Meadows, B.C. Jn. 4/73 - 2 -305 Alismataceae Alisma gramineum Gmel. Alisma plantago-aquatica L. Sagittaria suneata Sheld. Hydrocharitaceae Elodea n u t h a l l l i (Planch.) St. John Juncaginaceae Lllaea scilloides (Poir.) Hauman. Triglochin maritimum L. Najadaceae Najas f l e x i l i s (Willd.) Ross & Schmidt Potamogetonaceae -Potamogeton natans L. Potamogeton filiformis Pers. Potamogeton crispus L. Zannichelliaceae Zanichellia palustris L. Juncaceae Juncus oxymeris Engelm. Juncus buffonius L. Pitt Meadows, B.C. Jn. 4 ; / 7 3 Juncus effusus L. Pi t t Meadows, B.C. Jn. 4 / 7 3 Juncus sp. Pottinger Bog, Pi t t Meadows, B.C. May/73 Juncus balticus Willd. Juncus lesuerii Boland. Juncus supiniformis Engelm. Juncus c o v i l l e i Piper Luzula campestris (L.) D.C. Cyperaceae Carex crawfordii Fern. Carex rostrata Stokes P i t t Meadows, B.C. Jn. 4 / 7 3 , wet margins - 3 -306. Garex deweyana Schw. Carex flava L. Carex aquatalia Wahl. Carex bebbll Olney Carex onupta Bailey Carex paupercula Michx. Eleocharis palustris (L.) R. & S. Eriophorum chamissonis C.A. Mey, Pitt Meadows, B.C., sphagnum bog, Jn. 4/73 Scirpus microcarpus Presl., Pitt Meadows, B.C., sphagnum bog margin, Aug.5/73 Dulichium arundenaceum (L.) Br i t t . Scirpus cyperinus (L.) Kunth. Rhynchospora alba. (L.) Vabl. Gramineae Aira praecox L. Calamagrostis canadensis (Michx.) Beauv. Poa annua L. Pi t t Meadows, B.C.. ca. Jn. 4/73 . Lolium perenne L. Pitt Meadows, B.C. . Jn. 4/73 Poa compressa L. Jn. 4/73 Bromus sp. Jn. 4/73 Agrostis exarata Trin. Agrostis scabra Willd. S. Gilley SI. Aira praecox L. Glyceria grandis Wats. spiraea - B.C. grass Deschampsia caespilosa Anthoxanthum odoratum L. Pi t t Meadows, B.C. Jn. 4/73 Bromus carinatus H... & A. Festuca subuliflora Scribn. Cinna l a t i f o l i a (Trevir.) Griseb. Festuca myures L. Phalaris arundinacea L. P i t t Meadows, B.C. Jn. 4/73 Poa pratensis L. Pitt Meadows, B.C. Jn. 4/73 Agrostis semiverticellata (Forok.) Christ. Pottinger Bog, Pitt Meadows, B.C. Aug. 5/73. Actually more like A. longiligula H i t c h c , but not recorded for B.C. - OK for Wash. Glycera leptostachya Buckl. . P i t t Meadows, B.C. 307. " 4 -Hordeum geniculatum A l l . P i t t Meadows, B.C. Jn. 4/73 Holcus lanatus L. P i t t Meadows, B.C. Jn. 4/73 Festuca rubra L. Pitt Meadows, B.C., Sheridan H i l l Jn. 4/73 Alopecurus geniculatus L. Pitt Meadows, B.C. Jn. 4/73 Sparganiaceae Sparganium emersum Rehmann Typhaceae Typha l a t i f o l i a L. Araceae Acorus calumnus L. Lysichitum americanum Hulten & St. John, P i t t Meadows, B.C. Jn. 4/73 Lemnaceae Lemna minor L. Liliaceae Lilium columbianum Hanson Maianthemum dilatum (Wood) • Nels. & Macbr. Salicaceae Salix pedicellaris Pursh. Pitt Meadows, B.C. Jn. 4/73 Populus trichocarpa T. & G., Pi t t Meadows, B.C., dykes, Jn. 4/73 Salix lasiandra Pitt Meadows, B.C. Jn. 4/73 Betulaceae Betula occidentalis Hook. Pitt Meadows, B.C. Jn. 4/73 Almus rubra Bong. Pitt Meadows, B.C. Jn. 4/73 Almus sinuata (Regel.) Rydk. May 30/73 Corylus cornuta Marsh. Betula papyrifera Marsh. Myricaceae Myrica gale L. P i t t Meadows, B.C. Jn. 4/73 - 5 -308. Urticaceae Urtica dioica L. P i t t Meadows, B.C. Jn. 4/73 Polygonaceae Rumex acetosella L. Polygonum hydropiperoides Michx. Pitt Meadows, B.C. Aug. 5/73 Rumex acetosella L. Pi t t Meadows, B.C. Jn.4/73 Chenopodiaceae Chenopodium album L. Pi t t Meadows, B.C. Jn. 4/73 Portulacaceae Claytonja May 30/73 Montia spathulata (Dougl.) Howell Montia perfoliata (Donn.) Howell Caryophyllaceae Stellaria c r a s s i f o l i a Ehrb. Stell aria calycantha (Lebed.) Bong. Cerastium vulgatum L. Pitt Meadows, B.C. Jn. 4/73 Sagina procumbens L. Pitt Meadows, B.C. ca. Jn. 4/73 Sagina crassicaulis Wats. Nymphaceae Brasenia schreberi gmel. Nuphar polysepalum Engelm. Ranunculaceae Ranunculus occidentalis Nutt. Pitt Meadows, B.C. Jn. 4/73 Ranunculus flammula L. Ranunculus repens L. Pitt Meadows, B.C. Jn. 4/73 Fumariaceae Dicentra formosa (Andr.) Wallp. May 30/73 Cruciferae Rorippa nasturtium - aquaticum (L.) Schintz & Thell. - 6 -309. . Brassica campestris L. Pitt Meadows, B.C. Jn. 4/73 Raphanus (sativus L.) Pi t t Meadows, B.C. Jn. 4/73 Raphanus raphanistrum L. Pi t t Meadows, B.C. Jn. 4/73 Capsella bursa pastoris (L.) Medic. P i t t Meadows, B.C. Cardamine olyosperma Nutt. P i t t Meadows, B.C. Aug. 5/73 Rorippa islandica (Oed.) Borbas. P i t t Meadows, B.C. Aug. 5/73 Droseraceae Drosera rotundifolia L. Pitt Meadows, B.C. Jn. 4/73 sphagnum bog Saxifragaceae Tiarella t r i f o l i a t a L. Heuchera macrantha Dougl. Grossulariaceae Ribes sanguineum Parsh. Rosaceae Potentilla norvegica L. Amelanchier a l n i f o l i a Nutt. Rubus leucodermis Doug. Holodiscus discolor (Pursh.) Maxim. Prunus emarginata (Dougl.) Wallp. Rubus ursimus Cham. & Schlecht. Rubus discolor Weibe & Ness Rosa sp. Crataegus sp. Sorbus sp. Rubus sp. . Fragaria sp. Geuih sp. Potentilla sp. Pyrus fusca Raf. Pitt Meadows, B.C., dykes, etc. Jn. 4/73 Geum macrophyllum Willd. Jn. 4/73 Ribes sanguineum Pursh. May 30/73 - 7 -310 Prunus emarginata (Dougl.) Welp. May 30/73 Amelanchier a l n i f o l i a Nutt. May 30/73 Rubus ursinus Cham. & Schlecht. May 30/73 Rubus chamaemorus L. May 30/73 Potentilla palustris (L.) Scop. Geum macrophyllum Willd. Pit t Meadows, B.C. Jn. 4/73 Rubus leucodermis Docyl. Pitt Meadows, B.C. Jn. 4/73 Spiraea douglasii Hook. Pitt Meadows, B.C. Aug. 5/73 Potentilla biennis Greene. P i t t Meadows, B.C., roadside, heavy s o i l , Aug. 5/73 Rubus laciniatus Willd. Pit t Meadows, B.C. Jn. 4/73 Rubus spectabilis Pursh. Pitt Meadows, B.C. Jn. 4/73 Crataegus douglasii Lindl. Pit t Meadows, B.C. Jn. 4/73 Rosa nutkana Presi. Pit t Meadows, B.C. Jn. 4/73 Leguminoseae Trifolium procumbens L. P i t t Meadows, B.C. Jn. 4/73 Trifolium repens. Pitt Meadows, B.C. -Trifolium pratense Pitt Meadows, B.C. Jn. 4/73 Trifolium hybridurn P i t t Meadows, B.C. Jn. 4/73 Aceraceae Acer introduced Jn. 4/73, Pitt Meadows, B.C., polder Acer circinatum Pursh. May 23/73 Balsaminaceae Impatiens sp. Rhamnaceae Rhamnus pursheana D.C. Hypericaceae Hypericum perforatum L. Pitt Meadows, B.C. Aug. 5/73 Elatinaceae Elatine triandra Schkuhr 311. - 8 -Violaceae Viola sp. S. Gilley Slough Onagraceae , Epilobium angustifolium L. Pi t t Meadows, B.C. Jn. 4/73 Oenothera sp. Haloragidaceae Myriophyllum bippuroides Nut t. Umbelliferae Sium suave Walt. Cornaceae Cornus canadensis L. May 23/73 Cornus stolonifera Midex. Jn. 4/73 Ericaceae Kalmia occidehtalis Small Vaccjnium parvifolium Smith May 23/73 Gaultheria shallon Pursh. May 30/73 Vaccinium ovalifolium Smith Pitt Meadows, B.C. Vaccinium membraneeeum Dougl. Pitt Meadows, B.C. Jn. 4/73 Vaccinium oxycoccus L. Pi t t Meadows, B.C. Jn. 4/73 sphagnum bog Ledum groenlandicum Oeder P i t t Meadows, B.C., sphagnum bog Jn.4/73 : Kalmia p o l i f o l i a Wang. Pitt Meadows, B.C., sphagnum bog Jn. 4/73 Primulaceae Trientalis arctica Fisch. Pit t Meadows, B.C., Pottinger bog May/73 Gentianaceae Gentiana sceptrum Griseb. Sturgeon Slough, P i t t Meadows, B.C. Sept.21/72 Polemoniaceae Microsteris gracilis (Hook.) Greene - 9 -312. Menyanthaceae Menyanthes t r i f o l i a t e L. Pottinger bog, Pitt Meadows, B.C. May/73 Boraginaceae Myosotis laxa Lehm. Pi t t Meadows, B.C. Aug. 5/73 Labiatae Mentha arvensis L. Pitt Meadows, B.C. Aug. 5/73 Galeopsis tetrahit L. Pi t t Meadows, B.C., roadside Aug. 5/73 Stachys palustris L. Physostegia parviflora Nutt. = Dracocephalum n u t a l l i i  Lycopus americanus Muhl. Scrophulariaceae Digitalis purpurea L. May 30/73 Veronica sp. Pi t t Meadows, B.C. ca. Jn. 4/73 Veronica scutellata L. Lentibulariaceae Utricularia vulgaris L. Plantaginaceae Plantago major L. Rubiaceae Galium trifidum L. Galium sp. Sturgeon Slough, Pitt Meadows, B.C. Jn. 4/73 Caprifoliaceae Lonicera involucrata (Rich.) Banks Sheridan H i l l , P i t t Meadows, B.C. Jn. 4/73 Linnaea borealis . Sambucus racemos L. P i t t Meadows, B.C. Jn. 4/73 Symphoricarpos sp. Compositae Hypochaeris radicata L. Pi t t Meadows, B.C. Jn. 4/73 Plantago lanciolata L. Jn. 4/73 - 10 -313 Bidens sp. S. Gilley Slough Helenlum autumnale L. Spiraea - R.C. Grass ' Gnaphalium palustre Nutt. P i t t Meadows, B.C. Aug. 5/73 Senecio vulgaris L. Pi t t Meadows, B.C., roadside Aug. 5/73 Erigeron philadelphicus L. Pitt Meadows, B.C. Aug. 5/73 Matricaria matricarioides L. Pottingers bog, P i t t Meadows, B.C. Aug. 5/73 Anaphalis margaritacea (L.) B. & H. Pottingers bog, P i t t Meadows, B.C. Aug. 5/73 Taraxacum officinale Weber at a D I S T A N C E a waterfowl identification guide C A N A D I A N W I L D L I F E S E R V I C E v<7 This waterfowl identification guide originated with the Bureau of Sport Fisheries and Wildlife, Fish and Wildlife Service, United States Department of the Interior. The Cana-dian Wildlife Service has been able to make it available in Canada through the kind co-operation of those agencies and the U.S. Superintendent of Documents. Environment Canada Environnement Canada Wildlife Service Service de la Faune D U C K S at a D I S T A N C E a waterfowl identification guide by Bob Hines Issued under the authority of the Honourable Jack Davis, p .c , M . P . Minister of the Environment C A N A D I A N W I L D L I F E S E R V I C E S O U N D I D E N T I F I C A T I O N IS I M P O R T A N T Identifying waterfowl gives many hours of satisfying recreation to mi l l ions of people. A camera can catch color and action o f rare beauty. T h i s guide w i l l he you spot birds on the w i n g — i t shows their color ana plumage dur ing the fal l . K n o w i n g the species o f ducks and geese can be re-warding to both hunters and birdwatchers. A b i l i t y in-creases wi th experience but even experts make mistakes— so don't be discouraged i f progress seems slow at first. W h e n redheads or canvasbacks, or any other species, are protected because of their scarcity, it is essential that a hunter identify his target before he pulls the trigger. A n d when extra birds of certain species are permitted in the bag. hunters w h o know their ducks on the w i n g come out ahead. K n o w i n g a mal lard f r o m a merganser has another side: gourmets prefer the corn-fed greenhead to the fish duck. There is an index to the ducks on the back cover. Y o u can use it as a reference and also test yourself by trying to name each duck from its size, shape, and mark-ings—for y o u ' l l have to learn to identify your species quickly on the w i n g . W H A T TO L O O K FOR Habitat , action, color, shape, and voice—all help dis-t inguish one species from another. Shallow marshes and creeks normally attract few divers; large, deep bodies o f water are not usual feeding grounds o f puddle ducks. ^ (Continued on page 23) PUDDLE DUCKS Puddle ducks are typically birds o f fresh, shallow marshes and rivers rather than of large lakes and bays. They good divers, but usually feed by dabbling or t ipping rather than submerging. The speculum, or colored w i n g patch, is generally ir-ridescent and bright , and often a telltale field mark. A n y ducks feeding in croplands w i l l l ikely be puddle ducks, for most of this group are sure-footed and can walk and run wel l on land. Their food is mostly vege-table, and grain-fed mallards or pintails or acorn-fattened wood ducks are highly regarded. They ride higher in the water than divers, and launch themselves directly upward when r is ing, whether from land or water. MALLARD Most c o m m o n duck. Extremely hardy, winter ing as far north as it can find open water. F locks often leave the water in early m o r n i n g and late afternoon to feed i n nearby harvest fields, returning to marshes and creeks to spend the night. The flight is not particularly rapid ; voice of the hen is loud quack; of the drake, a lower-pitched kwek-kwek. BLACK DUCK A bird o f the eastern States, using the At lant ic and Mississippi flyways. Shy and wary, regarded as the wariest of all ducks. O f t e n seen i n c o m p a n y o f mal lards , but a long the At lant ic coast frequents the salt marshes and the ocean much more than mallards. Fl ight is swift; usually small flocks, in V s or angular lines. Voice is duplicate of mallards. Nervous birds, quick to take alarm. A g i l e fliers, usually in compact flocks. F l ight is fast, irregular, w i t h many twists and turns. W h i t e belly and forewing very conspicuous in the air. W h e n feeding, often accompanies d i v i n g ducks and robs them of food brought up f rom depths beyond the widgeon's capability. Drakes whistle; hens utter a l o u d kaow and a lower qua-awk. N o t plentiful anywhere; greatest numbers in the Cen-tral flyway, fewest in the A t l a n t i c flyway. The only puddle duck w i t h white in the speculum. Smal l , compact flocks fly swif t ly , usually i n a direct l ine. Wingbeats are rapid. Drakes whistle and kack-kack; hens quack l ike a mal-lard hen, but softer. Early fall migrant ; usual flight is steady and direct. W h e n startled, the small flocks fly erratically, twist ing and turning like teal. Greatest numbers occur in the Central and Pacific flyways. Aquatic animal life forms a third of its diet. Drakes call woh-wok and took-took; hens have a feeble quack. Very early migrant; the smal l , compact flocks fly swift ly, often l o w over marshes, t w i s t i n g and dodging around trees and bushes. T w i t t e r i n g calls in flight are easily heard. Pale-blue forewing patch is the best field mark. Drakes have a whis t l ing peep; hens a faint quack. GREEN-WINGED TEAL Q u i t e hardy—some birds stay as far N o r t h as open water is found. F l i g h t : sometimes in large flocks, al-ways swift, erratic, all members twist ing and circling as one unit. Nests as far north as Alaska , migrates south through all four flyways. Drakes whistle and twitter; hens have a slight quack. Rare east of the Rocky Mounta ins . F l ight characteristics l ike blue-wings, but usually there is only one family. They are trusting, often s low to take alarm. U n u s u a l l y silent species: drakes have a l o w chatter; hens a faint quack. PINTAIL Found in every flyway, most plentiful in the west. Extremely graceful, fast flier, fond of zig-zagging from great heights before leveling off for a landing. Equally agile on land; visits croplands to glean food. Drakes whistle; hens have a hoarse quack. Found in all flyways; most numerous in the Missis-sippi flyway. Frequents wooded streams and ponds; perches in trees. Flies through thick timber with speed and ease, and feeds readily on acorns, berries and grapes on the forest floor. Flight is swift and direct; flocks are usually small. Drakes call hoo-w-ett, often in flight; hens have a cr-r-ek when frightened. DIVING DUCKS D i v i n g ducks frequent the larger, deeper lakes and rivers, and coastal bays and inlets. The colored w i n g patches o f these birds lack the bril-nce of the speculums of puddle ducks, but are st i l l im-portant field marks in most species. Since most o f them have short tails, their huge, paddle feet may be used as rudders in flight, and are often v is ib le o n flying birds. W h e n launching into flight, most o f this group patter along the water before becoming airborne. They feed by d i v i n g , often to considerable depths. T o escape danger, they can travel great distances underwater, emerging only enough to show their head or b i l l t ip be-fore submerging again. T h e i r diets o f fish, shel l f i sh , m o l l u s k s , and aquatic plants make them second choice, as a group, for sports-men. Canvasbacks and redheads fattened on eel grass or w i l d celery are notable exceptions. Since their wings are small in proportion to the size and weight of their bodies, they have a rapid wingbeat in com-parison w i t h puddle ducks. DIVING DUCKS K V. D R A K E CANVASBACK Extremely powerful fliers, migrat ing in lines and ir-regular V s ; in feeding areas, compact flocks fly in in-definite formation. W i n g b e a t is rapid and noisy. N o r m a l l y late migrants. O n the water, body size and head shape distinguish them from scaups and redheads. Drakes croak, peep, and growl; hens quack, similar to a mallard hen. D R A K E REDHEAD Ranges coast to coast, often found w i t h canvasback. O n migrat ion, large flocks travel in V s ; in feeding areas, flocks fly in irregular formations. Movements in the air always seem to be hurried. Usual ly spends the day in large rafts in deep water; feeds morning and evening in shallower sections. Drakes purr and meow; hens have a loud squak. higher than hen mallard's. 12 D R A K E COMMON GOLDENEYE Distinctive wing-whistling sound in flight has earned the name of Whistlers. Active, strong-winged fliers, moving in small flocks, often high in the air. Frequently rise in rapid spirals. Exceedingly wary. Large numbers winter on Great Lakes and both seacoasts. Barrow's goldeneye, predominantly a westerner, differs mainly in the white crescent in front of the eye. Drakes have a piercing speer-speer; hens a low quack. Both are usually quiet. \ D R A K E H E N ®gj0 BUFFLEHEAD Drakes are conspicuous for their black and white design and small size. Flushes straight up or patters along on water. Flocks are small, usually mostly hens and young drakes. Flight is normally low; wingbeat is rapid. A late migrant, and will remain as far north as open water permits. Usually silent. Drakes squeak, and have a gutteral note; hens quack weakly. Lively and restless on the water and in the air. Late migrants, often moving south just ahead of freeze up. On local flights, closely bunched flocks move erratically, twist-ing and turning often. Easily confused with greater scaup. Best field mark is the light strip in the wings: short, half a wing length in the lesser scaup; longer, two-thirds the wing length, in the greater scaup. RING-NECKED DUCK Faint brown ring on neck never shows in the field; light bands at tip and base of bill are conspicuous. Up to a dozen in a flock fly in open formation; usually come directly into landing without circling. Hens are easily confused with female redheads; absence of dark edge on speculum helps distinguish from hen scaup. Drakes purr; hens are usually silent. 1 4 H E N D R A K E RUDDY DUCK ^ H E N & oREATER SCAUP ^ Flock movement is rapid, in fairly compact formation; over feeding areas they normally fly under hundred-foot altitude. The wings produce a loud rustling sound. j J B ^ Longer light strip showing through the wing is the ^^^j|^< best way to distinguish from the lesser scaup in the air. . V j Frequents the laigest bodies of water, where it rafts up during the day. Drakes utter a discordant scaup, scaup; hens are usually silent. This duck often swims away or dives rather than flushing. Rising from the water is awkward, seemingly with great effort. Once under way. the flight is sometimes jerky, noisy, and of uneven pace. Winter flocks are found in coastal areas, both salt and fresh water, from the Chesapeake Bay south, along the Rio Grande, and on the west coast. These birds are silent in the fall. 3!^ •it-Is COMMON MERGANSER Strong fliers; the flight is swift and direct, low over the water, often in "follow the leader" line. A very large duck; drakes show more white than any other species. Winters from ice-free water in the north to the coastal waters of the Southern States. The only call seems to be a startled croak. RED-BREASTED MERGANSER Flight is very similar to common mergansers, but drakes show far less conspicuous white. Juveniles and many adult drakes resemble hens during migration, for adult males grow out of eclipse plumage late. Winters principally along both coasts, as well as Gulf of Mexico. Voice; croaks, seldom heard. D R A K E HOODED MERGANSER Often seen in pairs, or very small flocks. The birds are graceful fliers, give an impression of great speed. Flushes straight up or patters along on water. Wingstrokes are short, rapid; the wings appear to blur. Seldom goes to salt water; wintering grounds are the inland waters in all coastal States. Only call is a series of coarse grunts. Mm TYPICAL FLOCK FORMATIONS M O S T P U D D L E D U C K S -L O O S E F O R M A T I O N *- ^ vr C A N V A S B A C K S — ^ ~V L I N E S O R L O O S E ^ G O L D E N E Y E S — S M A L L , L O O S E F L O C K S W I N G S " W H I S T L E " S I N G L E F I L E , L O W O V E R W A T E R J0L B U F F L E H E A D S — % S M A L L D U C K , S M A L L G R O U P S T E A L S — \ \ V I L O W , T W I S T I N G ^ N / t f F L I G H T M ml... D R A K E SPECIES WITH LIMITED RANGES These birds, except the tree ducks, are primarily of the sea. Scoter hunting is heaviest in New England, where all three species are locally known as "coots." Some flocks migrate along the coast as far as the Carolinas on the Atlantic and lower California on the Pacific. Harlequins go little further south than Long Island and Puget Sound and north to Alaska. Oldsquaws have essentially the same range, plus the Great Lakes. Fulvous tree ducks are beginning to spread into the east from Louisi-ana west to California, while the black-bellied is still restricted to Texas. Common eiders are only in the North Atlantic, but related forms occur in the northwest and Alaska. HEN F U L V O U S T R E E D U C K B L A C K - B E L L I E D T R E E D U C K C O M M O N E I D E R 1 9 C O M M O N M E R G A N S E R ECLIPSE PLUMAGE D R A K E S | E M E R G I N G F R O M I E C L I P S E Drakes of nearly all species lose their color-ful attire after mating, and for about a month look like adult females. Their return to breed-ing plumage is slow. Depending on the time of mating, it can be well into the fall, or even winter, before drakes can be told from hens in flight. Teals and shovelers are late in regaining their bright breeding plumage, and many mi-grate in the duller eclipse plumage. The body feathers of all ducks are shed twice each year to account for this change; the wing feathers are molted but once. Thus the wings are the same pattern and color the year around. * D R A K E F A L L P L U M A G E WHAT TO LOOK FOR — (Continued from page 4) The maneuvers of a flock in the air can help indicate the species. Mallards, pintails, and widgeons form loose groups; teals and shovelers flash by in small bunches; mergansers often appear in single file; canvasbacks shift from waving lines to temporary V s ; redheads "boil up" in short flights from one end of a lake to the other. Closer up, individual silhouettes can show large heads or small, broad bills or narrow, fat bodies or slender, long tails or short. Trained observers also identify ducks from the wingbeats: they may be fast or slow, short rapid flut-ters or long strokes. At close range, color areas can be positive. Depend-ing on light conditions they may or may not appear in their true color, but their size and location are a key to identity. The sound of wings can be as important as that of voice. The pinions of goldeneyes whistle in flight; the swish of wood ducks is different from the steady rush of canvasbacks. Not all ducks quack: many whistle, squeal, or grunt. Experience can teach you the difference. © Information Canada Ottawa, 1 9 7 4 Price 25 cents Catalogue No. CW66-3665 Montreal Lithographing L t d . TT- F L O C K A C T I O N S I L H O U E T T E S C O L O R A R E A S S O U N D 


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