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Foods and habitat of four anatinids wintering on the Fraser Delta tidal marshes Burgess , Thomas Edward 1970

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FOODS AND HABITAT OF FOUR ANATINIDS WINTERING ON THE FRASER DELTA TIDAL MARSHES by THOMAS EDWARD BURGESS B.Sc. U n i v e r s i t y o f V i c t o r i a , 1964 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n t he Department o f ZOOLOGY We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA November, 1970 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of Zoology  The University of British Columbia Vancouver 8, Canada Date A p r i l 29, 1971 ABSTRACT The Fraser d e l t a t i d a l marshes are important f o r migrating and w i n t e r i n g ducks, i n p a r t i c u l a r , M a l l a r d , P i n t a i l , Widgeon, and Green-winged T e a l . A g r i c u l t u r a l , r e s i d e n t i a l , and i n d u s t r i a l development threaten the t i d a l marshes with d e s t r u c t i o n and q u a l i t y l o s s . In order to preserve and protect the most v a l u a b l e a r e a s , and perhaps improve the c h a r a c t e r i s t i c s which a t t r a c t ducks, i t was considered necessary to determine areas of most v a l u e , and the environmental c h a r a c t e r i s t i c s which could be improved. A study of the occurrence and food h a b i t s of ducks on the t i d a l marshes was considered to be the best means of determining the importance of each u n i t . The r e l a t i v e importance of the t i d a l marshes for l o a f i n g and feeding h a b i t a t was i n d i c a t e d from a s y n t h e s i s of a l l a v a i l a b l e information on duck use of the e n t i r e d e l t a a r e a . A e r i a l censuses conducted throughout two winters provided data on the d i s t r i b u t i o n and abundance of M a l l a r d , P i n t a i l , Widgeon, and Green-winged Teal on the foreshore and adjacent upland. It was found that an annually v a r i a b l e population of ducks was present from September u n t i l May, w i t h the l a r g e s t numbers o c c u r r i n g during f a l l and s p r i n g m i g r a t i o n s . The t i d a l marshes a t t r a c t e d approximately one-half the ducks on the d e l t a s — w i t h the l a r g e s t proportions o c c u r r i n g in September, e a r l y October, l a t e March, A p r i l , and May.. A l l four census u n i t s of the t i d a l marsh a t t r a c t e d s i m i l a r w i n t e r t o t a l s of ducks although the r e l a t i v e number at each u n i t v a r i e d throughout the w i n t e r . I I I As a l l of the t i d a l marshes appeared important to ducks, the features of a l l of them were s t u d i e d . Area was determined from a e r i a l photographs, and topographical r e l a t i o n s h i p s were determined from known ( t i d e l e v e l s . Composition and d i s t r i b u t i o n of veg e t a t i o n was determined from l i n e t r a n s e c t s . R e l a t i v e production of seeds was determined from l i n e t r a n s e c t s and seed samples. The t i d a l marshes were found to cover ap p r o x i m a t e l y 3,733 a c r e s , s l o p i n g from the approximately t h i r t e e n foot to the seven foot t i d e l e v e l . A s i x to eighteen inch " d r o p - o f f " , which u s u a l l y occurred near the ten foot t i d e l e v e l , separated the t i d a l marsh i n t o an upper and lower zone, each with a d i f f e r e n t v e g e t a t i v e composition. Fourteen p l a n t species were found, of which f i v e Cyperaceae s p e c i e s , Sci rpus arfieri canus , Carex lyngbye? , E l e o c h a r i s macrostachya , Sci rpus  pa 1udosus , and Sci rpus validus•composed n i n e t y - t h r e e percent of a l l p l a n t s . The f i r s t two s p e c i e s , dominant on the lower and upper zones r e s p e c t i v e l y , formed seventy percent of a l l p l a n t s . D i s t r i b u t i o n appears to be determined by the degree of t i d a l f l o o d i n g , the degree of l o c a l drainage, and p o s s i b l y by undemonstrated d i f f e r e n c e s in s o i l and water s a l i n i t y . Seed production v a r i e d a n n u a l l y , and was r e l a t e d to the degree of t i d a l f l o o d ? ng. Sci rpus v a l i d u s and Carex Lyngbye? produced the most seeds, followed next by Sci rpus'amer ? canus. Ducks were c o l l e c t e d on the t i d a l marshes and adjacent a g r i c u l t u r a l areas. A n a l y s i s of t h e i r stomach contents revealed that Carex  Lyngbye?, S c i r p u s v a l i d u s a n d S c i rpus amer?canus were the most important.— t i d a l marsh food i terns.' Polygonum lapath ? foliurn and P. pers i c a r i a were the most important seed foods taken on the a g r i c u l t u r a l areas. Although M a l l a r d , i i i P i n t a i l , and Green-winged Teal consumed mostly seeds, Widgeon consumed p r i m a r i l y green v e g e t a t i o n , i n c l u d i n g w i n t e r r y e , L o l i urn sp., and several Gramineae s p e c i e s . A s y n t h e s i s of the a v a i l a b l e information i n d i c a t e s that the t i d a l marshes were most important as l o a f i n g areas from October u n t i l January, w h i l e during the remainder of the p e r i o d , from September u n t i l May, they were a l s o important f o r the p r o v i s i o n of food. The c o n t r o l of water l e v e l s , by d i k i n g and pumping, appears to be e s s e n t i a l f o r the improvement and p r o t e c t i o n of the t i d a l marshes. TABLE OF CONTENTS CHAPTER PAGE 1. INTRODUCTION TO THE STUDY 1 Basic Considerations 1 Previous Research 2 Study Objec t i v e s 5 11. THE STUDY AREA 6 U l . STUDY METHODS . 11 Duck D i s t r i b u t i o n 11 Delta foreshore and adjacent uplands . 11 T i d a l marshes only . . 1 5 Segments of the t i d a l marsh 15 T i d a l Marsh Features . . . 16 Area 16 Topography 16 Vegetation composition . . 17 Duck food production 18 Duck Food Habits 18 W. DUCK OCCURRENCE . 21 D e l t a Foreshore and Adjacent Uplands 21 T i d a l Marsh Only 29 Segments of the T i d a l Marsh 30 Conclusions 33 V. TIDAL MARSH FEATURES 34 Extent and Topography 35 C ' V Vegetation Composition and D i s t r i b u t i o n 37 R e l a t i v e Duck Food Production k8 Conclusions 55 VI . DUCK FOOD HABITS 57 M a l l a r d Food Habits 59 P i n t a i l Food Habits 62 Widgeon Food Habits 65 Green-winged Teal Food Habits 68 Conclusions 71 V l l . DISCUSSION 72 Duck Occurrence . . 72 T i d a l Marsh Features . . . . . . . . . . . . . . lb D i s t r i b u t i o n of plant species lb Annual seed production . . . 76 R e l a t i v e Importance of the T i d a l Marshes and A g r i c u l t u r a l Areas 80 Improvements on the T i d a l Marshes 88 V l l 1 . CONCLUSIONS 90 BIBLIOGRAPHY . Sb APPENDICES 97 LIST OF TABLES TABLE PAGE 1. Cumulative Percentages of Occurrence of Four Duck Species Counted at Each of Four T i d a l Marsh Census Units During the Winter of 1966 to 1967 . 32 11. The Plant Species Composition on Five Units of the Fraser River T i d a l Marshes Expressed as Percent Frequency, and the Acreage Covered by Each Plant Species 38 111. Some Habitat C h a r a c t e r i s t i c s of the T i d a l Marsh Plant s . . . 39 IV. Seed Production by Healthy Seed Heads of the Five Most Abundant Plant Species on the Fraser Delta T i d a l Marshes i n I966 . 51 V. The Percentage of Stems Producing Seeds For The Five Most Abundant Plant Species on the Fraser Delta T i d a l Marshes in 1966 53 V I . Seed Production Indices f o r the Five Most Abundant Plant Species on the Fraser Delta T i d a l Marshes i n 1966 5k V l l . The Three-year Average Percentage of Productive Stems, of the Five Most Abundant Plant Species on the Fraser Delta T i d a l Marsh From 1965, 1966, and 1967 . ' 78 V I I V I I 1 . E s t i m a t e d Long-term Seed P r o d u c t i o n I n d i c e s f o r t h e F i v e Most Abundant P l a n t . S p e c i e s on t h e F r a s e r D e l t a T i d a l Marshes 79 LIST OF FIGURES FIGURE PAGE 1 . The Study Area 7 2. The Study Area and A e r i a l Census Route . . . 12 3. M a l l a r d Population Fraser R i v e r Delta . 23 4. P i n t a i l Population Fraser River Delta 2k 5. Widgeon Population Fraser River Delta . . . . . . . . 25 6. Green-winged Teal Population Fraser R i v e r Delta 26 7. The Total Duck Population Occurring on the T i d a l Marshes in 1965 " 1966 and 1966 - 7 967 , in Numbers, and as a Percentage of the Total Delta Population 28 8. Representative T i d a l Marsh P r o f i l e s Showing the D i s t r i b u t i o n of S i x Abundant Plant Species . . . . . . . . . . . 36 9. D i s t r i b u t i o n of Predominant T i d a l Marsh S p e c i e s , Brunswick Hunting Ground - Westham Island 43 10. D i s t r i b u t i o n of Predominant T i d a l Marsh Species, Westham Island - R e i f e l Island . . 44 11. D i s t r i b u t i o n of Predominant T i d a l Marsh Species, Lulu Island - South . . . . . . . 45 12. D i s t r i b u t i o n of Predominant T i d a l Marsh Sp e c i e s , Lulu Island - North 46 13. D i s t r i b u t i o n of Predominant T i d a l Marsh Sp e c i e s , Sea Island - lona Island 47 14. The R e l a t i v e Importance of Food I terns i n the Winter Diet of M a l l a r d From the Fraser Delta T i d a l Marshes . . . . . . 61 i x 15. The R e l a t i v e Importance of Food Items in the Winter Diet of P i n t a i l From The Fraser Delta T i d a l Marshes 64 16. The R e l a t i v e Importance of Food I terns in the Winter Diet of Widgeon From The Fraser Delta T i d a l Marshes 67 17. The R e l a t i v e Importance of Food I terns i n the Winter Diet of Green-winged Teal From The Fraser Delta T i d a l Marshes 70 ACKNOWLEDGMENTS Throughout vario u s p o r t i o n s of the research period spent in prep a r a t i o n f o r t h i s t h e s i s , I received f i n a n c i a l a s s i s t a n c e from the Department of Zoology of the U n i v e r s i t y of B r i t i s h Columbia, the Canadian W i l d l i f e S e r v i c e , and Canadian Industries L i m i t e d . During much of the period spent in w r i t i n g up the t h e s i s , and in preparing maps, graphs, and f i g u r e s , I received f i n a n c i a l , c l e r i c a l , and t e c h n i c a l a s s i s t a n c e from the F i s h and W i l d l i f e D i v i s i o n , and the Technical D i v i s i o n , both of the A l b e r t a Department of Lands and F o r e s t s . The a s s i s t a n c e received from these agencies i s g r a t e f u l l y acknowledged. The a i r c r a f t used .for a e r i a l censuses were paid f o r by the Vancouver o f f i c e of the Canadian W i l d l i f e S e r v i c e . T h e i r p r o f e s s i o n a l s t a f f provided v a l u a b l e advice on census techniques, and I am p a r t i c u l a r l y g r a t e f u l in t h i s regard to Mr. Bob H a r r i s , Mr. B i l l M o r r i s , and Mr. Er n i e T a y l o r . Other i n d i v i d u a l s who a s s i s t e d me during the a e r i a l censusing were a f e l l o w s t u d e n t , Mr. Ray Ha l l a d a y , Mr. Bryon Gates, Regional W i l d l i f e B i o l o g i s t f o r the B r i t i s h Columbia F i s h and W i l d l i f e Branch, and Dr. Ron Ryder, from the U n i v e r s i t y of Colorado. A s s i s t a n c e in the i d e n t i f i c a t i o n of p l a n t s and seeds, studies of seed p r o d u c t i o n , and mapping of v e g e t a t i o n , was g r a t e f u l l y received from Dr. W. B. S c h o f i e l d , Mr. Er n i e T a y l o r , the s t a f f of the U n i v e r s i t y of B r i t i s h Columbia Herbarium, Mr. Ray Hal l a d a y , and Mr. B i l l M o r r i s . Specimens used in the a n a l y s i s of duck food h a b i t s were obtained from f e l l o w students Mr. Doug M o r r i s o n , and Mr. Ray Hal l a d a y , and from members of the Delta/Ladner Rod and Gun Club. One of these members, Mr. xi Russ Young, a l s o provided a black Labrador R e t r i e v e r f o r use in c o l l e c t i n g ducks. Mr. Robert Husband, Mr. Jim Savage, and Mr. Hugh Monahan, provided numerous ducks f o r a n a l y s i s , and were most h e l p f u l in v o l u n t e e r i n g information on duck movements and behaviour. Their e n t h u s i a s t i c co-o p e r a t i o n deserves s p e c i a l thanks. During the course of research and f i n a l w r i t i n g , I have been f o r t u n a t e in r e c e i v i n g c o n s i d e r a b l e encouragement and c o n s t r u c t i v e c r i t i c i s m from my committee chairmen, Dr. H. D. Fisher and Dr. J . F. B e n d e l l . Other committee members, Dr. W. B. S c h o f i e l d and, in p a r t i c u l a r , Dr. P. J . Bandy of the W i l d l i f e Research D i v i s i o n , B r i t i s h Columbia Fish and W i l d l i f e Branch, a l s o provided v a l u a b l e d i r e c t i o n in the p r e p a r a t i o n of the t h e s i s . Throughout the course of the research and w r i t i n g leading up to the completion of t h i s t h e s i s , 1 have received c o n s i d e r a b l e a s s i s t a n c e , p a t i e n c e , and encouragement from my w i f e , Judy. For t h i s I am p a r t i c u l a r l y g r a t e f u l . CHAPTER 1 INTRODUCTION TO THE STUDY 1. BASIC CONSIDERATIONS The Fraser River d e l t a i s the most n o r t h e r l y s i z e a b l e w i n t e r i n g area f o r waterfowl on the P a c i f i c c o a s t . A d d i t i o n a l l y , i t i s a r e s t i n g area p r o v i d i n g h a b i t a t f o r large numbers of waterfowl passing through the d e l t a during the f a l l and s p r i n g m i g r a t i o n s . A n n u a l l y , from August to May, hundreds of thousands of ducks, and somewhat l e s s e r numbers of geese and swans, are dependent on the d e l t a f o r food and l o a f i n g s i t e s . Most of these w i n t e r i n g and m i g r a t i n g waterfowl are a t t r a c t e d to areas adjacent to the s e a , a s u b s t a n t i a l p o r t i o n of which support freshwater marshes. These t i d a l marshes are believed to be of great importance i n p r o v i d i n g food and l o a f i n g s i t e s f o r a l l types of w a t e r f o w l , and f o r ducks in p a r t i c u l a r . In recent y e a r s , pressures to develop t i d a l marshlands have been b u i l d i n g . Some of these f e r t i l e t r a c t s of land have already been reclaimed f o r a g r i c u l t u r a l purposes, and i n some cases have been subsequently used f o r r e s i d e n t i a l development. Pressures from r a p i d l y growing human populations are i n c r e a s i n g t h i s t r e n d . The p r o x i m i t y of the t i d a l marshes and adjacent lands to deep sea t r a n s p o r t a t i o n routes makes them a t t r a c t i v e f o r the development of shipping f a c i l i t i e s and i n d u s t r y . This l a t t e r threat to waterfowl h a b i t a t i s p a r t i c u l a r l y s e r i o u s . It w i l l r e s u l t in a d i r e c t l o s s of h a b i t a t , and there i s a p o s s i b i l i t y that accompanying p o l l u t i o n may reduce the value of the remaining marshlands. To compensate f o r past and expected f u t u r e losses to t i d a l marsh h a b i t a t , i t i s necessary to preserve and protect the most important segments, and increase t h e i r a t t r a c t i v e n e s s to waterfowl where p o s s i b l e . To do t h i s , knowledge of the r e l a t i v e importance of each marsh u n i t , and the p a r t i c u l a r c h a r a c t e r i s t i c s a t t r a c t i v e to waterfowl i s r e q u i r e d . It i s the purpose of t h i s study to provide s u f f i c i e n t information on the importance and c h a r a c t e r i s t i c s of the t i d a l marshes to b e t t e r enable those r e s p o n s i b l e f o r waterfowl management to preserve, p r o t e c t and improve them. Ducks are the most widely o c c u r r i n g group of waterfowl on the Fraser d e l t a . The four most abundant are: Mai l a r d (Anas p i a t y r y h c h o s ) ; P i n t a i 1 (Anas a c u t a ) ; Widgeon or Baldpate (Anas americana): and Green-winged Teal (Anas c r e c c a ) . A study of d i s t r i b u t i o n and r e l a t i v e abundance and the food h a b i t s of these four duck species provides the best means of a s c e r t a i n i n g the r e l a t i v e importance of t i d a l marshes and uplands, and the value of each to wa t e r f o w l . 1 1 . PREVIOUS RESEARCH J . A. Munro's s t u d i e s ( 1 9 3 9 , 19^3, 1 9 ^ , 1 9 4 9 a , 1 9 ^ 9 b ) deal in a very general fashion with migration and w i n t e r i n g periods f o r M a l l a r d , P i n t a i l , Green-winged Teal and Widgeon i n the Fraser River d e l t a . These s t u d i e s were based p r i m a r i l y on banding r e t u r n s , contain l i t t l e census d a t a , and do not deal s p e c i f i c a l l y w i t h ducks on the t i d a l marshes. However, some information concerning food h a b i t s was provided from small samples taken from several s c a t t e r e d l o c a t i o n s throughout the e n t i r e d e l t a . C o t t l e ' s study (1949) of food h a b i t s i s a l s o based on a small sample, p a r t i c u l a r l y i n regard to P i n t a i l and Widgeon. It is of c o n s i d e r a b l e i n t e r e s t , however, because the ducks sampled were taken on or near t i d a l marshes. His sample i n d i c a t e d that ducks may have obtained a s u b s t a n t i a l p o r t i o n of t h e i r food from c u l t i v a t e d areas. Furthermore, in 1949, oats (Avena sp.) was an important item in the d i e t of M a l l a r d , P i n t a i l , and Green-winged T e a l . Since then, several changes in a g r i c u l t u r a l p r a c t i c e s have occurred on the d e l t a , i n c l u d i n g a reduction in the amount of cereal grains grown. To the extent that C o t t l e ' s work i s based on a small sample of ducks feeding on lands managed under d i f f e r e n t a g r i c u l t u r a l p r a c t i c e s than those e x i s t i n g today, h i s information must be treated as being of only general v a l u e . Two d e s c r i p t i v e references by W. A. Benson (1961, 1964) provide some information on duck numbers. Benson expressed d i f f i c u l t y in determining the actual number of ducks u t i l i z i n g the d e l t a w h i l e they were m i g r a t i n g . He a l s o presented data from several years showing great v a r i a t i o n s i n the number of ducks o c c u r r i n g during the month of January. These w i l l be discussed in a l a t e r s e c t i o n . Benson suggested that the t i d a l marshes were used p r i m a r i l y as l o a f i n g a r e a s , w i t h feeding being of secondary importance. He stressed the importance of farm lands p r o v i d i n g food f o r ducks, and mentioned regular night f l i g h t s between them and the t i d a l marshes. A d d i t i o n a l l y , Benson provided b r i e f d e s c r i p t i o n s of the t i d a l marshes, and suggested some reasons f o r the d i s t r i b u t i o n of some plant s p e c i e s . U n f o r t u n a t e l y , he provided very l i t t l e numerical data on duck numbers and food h a b i t s , and h i s suggestions regarding p l a n t d i s t r i b u t i o n are not supported by any d a t a . Only two references d e a l i n g w i t h freshwater t i d a l marshes were found. Lemieux's work (1959) on the biology of the Greater Snow Goose (Chen hyperborea at 1 a n t i c a ) includes a d e s c r i p t i o n of the t i d a l marshes on the S t . Lawrence R i v e r . These appear s i m i l a r to those of the Fraser D e l t a , but most of the l e s s abundant pla n t species are d i f f e r e n t . A study by J e f f r e y (1948) d e a l t with the t i d a l marshes in Port Susan and Skagit Bays in Washington S t a t e . J e f f r e y ' s work i n d i c a t e s a remarkable s i m i l a r i t y between the marshes of Skagit and the Fraser d e l t a . The p l a n t s p e c i e s , t h e i r growth and development, and the general appearance of the marshes were almost i d e n t i c a l . J e f f r e y ' s study included a s e c t i o n on the production of seeds by the most abundant pla n t s p e c i e s . The p h y s i c a l c h a r a c t e r i s t i c s of the t i d a l marshes are described in several r e f e r e n c e s . The c l i m a t e of the lower mainland of B r i t i s h Columbia i s described in a paper by Kendrew and Kerr ( 1955 ) . Harry and Wright (1967) deal with the c l i m a t e of Vancouver C i t y . The annual weather summary f o r the Vancouver I n t e r n a t i o n a l A i r p o r t on Sea Island (Canada Department of T r a n s p o r t , 1967) provides more recent data from an area adjacent to the t i d a l marshes. References to the s o i l s of the t i d a l marshes are found i n works by Armstrong ( 1 9 5 6 ) , and Sprout and Holland ( 1 9 5 9 ) . D e s c r i p t i v e material d e a l i n g r e s p e c t i v e l y w i t h s a l i n i t y and t i d a l movements of the water on the t i d a l marshes i s included in a report by the P a c i f i c Oceanographic Group ( 1 951 ) , and in the annual Tide and Current Tables by the Canadian Hydrographic S e r v i c e (1965, 1966, 1967 ) -5 111. STUDY OBJECTIVES In the l i g h t of the stated purpose of t h i s study, and because of the shortage of recent comprehensive i n f o r m a t i o n , the f o l l o w i n g o b j e c t i v e s were e s t a b l i s h e d : 1. To determine the numbers of M a l l a r d , P i n t a i l , Widgeon, and Green-winged Teal o c c u r r i n g annually over the e n t i r e d e l t a foreshore and adjacent upland areas from September to May. , 2. To assess the r e l a t i v e importance of the t i d a l marshes in a t t r a c t i n g ducks by comparing the numbers of ducks present on them w i t h the t o t a l numbers present on the e n t i r e d e l t a f o r e s h o r e . 3. To i n d i c a t e the r e l a t i v e importance of separate segments of the t i d a l marsh in a t t r a c t i n g ducks by comparing the numbers and species composition of the ducks present. h. To determine the v e g e t a t i v e composition, e x t e n t , and topography of the t i d a l marsh segments important to ducks. 5. To determine the r e l a t i v e production of duck food by the most abundant t i d a l marsh p l a n t s . 6. To determine the food h a b i t s of M a l l a r d , P i n t a i l , Widgeon, and Green-winged Teal using t i d a l marshes. 7. To s y n t h e s i z e the information determined from the above o b j e c t i v e s in order to b e t t e r i n d i c a t e the r e l a t i v e importance of the t i d a l marshes in p r o v i d i n g food and l o a f i n g s i t e s f o r ducks, and i n order to i n d i c a t e c h a r a c t e r i s t i c s of the t i d a l marshes which might be improved. CHAPTER 11 THE.STUDY AREA The study a r e a , shown in Figure 1, l i e s at the mouth of the Fraser R i v e r , d i r e c t l y south of the C i t y of Vancouver. It includes three major and a s e r i e s of minor d e l t a i c i s l a n d s , and a large f l a t area a d j o i n i n g the mainland to the south and e a s t . This encompasses almost one hundred square m i l e s . The north arm of the r i v e r marks the northern l i m i t of the f l a t l a n d . The d e l t a a d j o i n i n g the mainland continues south and east around Boundary Bay almost to the Canada - United States border. A smaller area of the d e l t a to the east of Mud Bay i s drained by the Serpentine and Nicomekl R i v e r s . A large p o r t i o n of the d e l t a has been reclaimed from t i d a l marshes at one time or another and i s now protected from t i d a l water by dikes of va r i o u s ages. F i e l d s adjacent to the dikes are separated from them by s p o i l d i t c h e s used f o r drainage. As on other d e l t a s , natural drainage i s poor, but has been improved by d i t c h i n g . Some of these d i t c h e s produce abundant a q u a t i c growth and are a t t r a c t i v e to wa t e r f o w l . Much of the d e l t a i s under a g r i c u l t u r a l development, although i n c r e a s i n g u r b a n i z a t i o n i s changing t h i s . Crops include sugar beet seeds, peas, beans, c o r n , potatoes, b a r l e y , o a t s , c l o v e r , a l f a l f a , and hay. In -a d d i t i o n , some land i s seeded to forage crops and permanent pasture used by c a t t l e . The t i d a l marshes l i e j u s t o u t s i d e the dikes on the seaward s i d e F I G U R E i THE STUDY AKEA of the d e l t a i s l a n d s and mainland. There are f i v e g e o g r a p h i c a l l y d i s t i n c t t i d a l marsh u n i t s as f o l l o w s : lona and Sea I s l a n d s , Lulu I s l a n d , R e i f e l I s l a n d , Westham I s l a n d , and Brunswick Hunting Ground. They are part of Sturgeon and Roberts Banks, but cover l e s s than o n e - f i f t h t h e i r a r e a . Vegetation occurs on an unknown acreage adjacent to the d i k e s , from lona Island on the north to Brunswick Hunting Ground on the south s i d e of Canoe Pass. A d d i t i o n a l l y , t i d a l marshes occur in the three arms of the r i v e r . The c l i m a t e of the t i d a l marshes and surrounding d e l t a i s described as modified maritime (Kendrew and K e r r , 1955). The adjacent S t r a i t of Georgia has a moderating i n f l u e n c e producing r e l a t i v e l y warm winter s and cool summers f o r t h i s l a t i t u d e . P r e c i p i t a t i o n and temperature are the c l i m a t i c f a c t o r s of greatest importance to t h i s study. Appendices 1 and 2 i l l u s t r a t e the frequency of r a i n f a l l and the mean maximum and minimum temperatures f o r the Vancouver C i t y area (Harry and Wright, 1967). The average annual p r e c i p i t a t i o n recorded at Vancouver I n t e r n a t i o n a l A i r p o r t on Sea Island i s 39.3^ inches (Canada Department of T r a n s p o r t , 1967). Almost 75% of t h i s f a l l s from October to March and t h i s heavy w i n t e r p r e c i p i t a t i o n u s u a l l y r e s u l t s in larg e areas of a g r i c u l t u r a l land being f l o o d e d . Freezing temperatures of more than a few days d u r a t i o n are very i n f r e q u e n t , but may occur in December, January, and February. As a r u l e , January is the c o l d e s t month and lengthy f r e e z i n g p e r i o d s , i f they occur at a l l , do so in January. Lengthy periods of f r e e z i n g weather, whether accompanied by snow or n o t , render the a g r i c u l t u r a l areas l a r g e l y u n s u i t a b l e f o r duck feeding purposes (Munro, 19^3). The t i d a l marshes, however, r a r e l y f r e e z e o v e r , and snow f a l l i n g on them melts q u i c k l y . 9 They a r e , t h e r e f o r e , s t i l l a v a i l a b l e as feeding and l o a f i n g s i t e s . But in e x c e p t i o n a l l y c o l d p e r i o d s , the b r a c k i s h water f r e e z e s , forming i c e sheets which r i d e up and down with the t i d e . Under such unusual circumstances, feeding i s probably d i f f i c u l t f o r the ducks remaining on the d e l t a . The s o i l s of the t i d a l marshes, as described by Sprout and Holland (1959) are s i l t loam or s i 1 t y c l a y loam w i t h textures down to f i n e sand encountered. The top two or three f e e t contain moderate amounts of organic matter, and some g l e y i n g o c c u r s . The thickness of the loam, v a r i e s c o n s i d e r a b l y , and i t i s un d e r l a i n by a lay e r of sand up to 50 f e e t in depth. There i s some i n d i c a t i o n that the thickness of the loam decreases towards the sea and away from the v e g e t a t i o n . S o i l samples, taken from a r e l a t i v e l y high marsh area on R e i f e l I s l a n d , gi ve a mean pH of 7.01 and a mean t o t a l d i s s o l v e d s a l t s of 555 parts per m i l l i o n . But these are not n e c e s s a r i l y r e p r e s e n t a t i v e of the whole t i d a l marsh. The complete data are presented in Appendix 3 . The t i d a l marsh s o i l s are always very wet, s i n c e they are f r e q u e n t l y saturated with b r a c k i s h water at high t i d e s . Even at low t i d e , f r e e surface water remains on poorly drained a r e a s . S o i l s of the t i d a l marshes are c o n s t a n t l y being b u i l t up as a r e s u l t of the d e p o s i t i o n of s i l t from the r i v e r t i d a l a c t i o n . Dr. W. K. Mathews (personal communication) s t a t e s that the mud f l a t s are advancing at an average rate of 7.5 f e e t per year along a 12,000 foot f r o n t o f f the main channels, and l e s s or not at a l l away from the main channels. If the average slope of the f l a t s (3 f e e t per mile) remains c o n s t a n t , t h i s means an increase i n e l e v a t i o n of .00k f e e t per ye a r , or one foot per 250 y e a r s . However, r e d i s t r i b u t i o n of sediments by wave a c t i o n and organisms i n v a l i d a t e t h i s c a l c u l a t i o n f o r anything l e s s than a century. A c c r e t i o n by the t i d a l -marsh i s known by l o c a l r e s i d e n t s to be much f a s t e r than t h i s . They i n d i c a t e that on Westham Island the t i d a l marsh has increased four f e e t in e l e v a t i o n i n l e s s than 35 y e a r s . F u r t h e r , the e r e c t i o n of j e t t i e s on Sea Island and near Tsawwassen i s thought to have co n s i d e r a b l y increased the rate of s o i l d e p o s i t i o n there (Benson, 1961). The permanency and q u a l i t y of the water make the d e l t a marshes unique. The water i s t i d a l , r i s i n g and f a l l i n g twice d a i l y . But due to the strong i n f l u e n c e of the Fraser R i v e r , the water f l o o d i n g the marshes i s almost e n t i r e l y f r e s h . A study of s a l t c o n c e n t r a t i o n in the water of the Fraser River Estuary ( P a c i f i c Oceanographic Group, 1951) i n d i c a t e s that the s a l t water f r o n t i s well o f f shore from the t i d a l marshes. Sampling s t a t i o n s placed in open water beyond the mud f l a t s revealed s a l t c o n c e n t r a t i o n s of l e s s than 10,000 part s per m i l l i o n f o r the top 10 f e e t of water, and l e s s than 20,000 parts per m i l l i o n f o r the. water 10 to 20 fe e t deep. The presence of non-halophytic p l a n t species in the marsh a l s o i n d i c a t e s the presence of non-saline water. The p a t t e r n of the t i d e s over the t i d a l marshes i s such that during the summer, low t i d e s occur i n d a y l i g h t hours, w h i l e high t i d e s occur during the n i g h t . In w i n t e r , t h i s p a t t ern i s reve r s e d , so that t i d e s are r e l a t i v e l y high during the shorter d a y l i g h t hours. During the sp r i n g and autumn months extremely low t i d e s occur around dawn and dusk. This p a t t e r n of d i u r n a l low t i d e s in summer aid s the growth of the marsh p l a n t s . CHAPTER 111 STUDY METHODS 1. DUCK DISTRIBUT I ON Del ta foreshore and •' adjacent uplands. A s e r i e s of a e r i a l censuses conducted over the e n t i r e d e l t a foreshore and adjacent uplands during the winters of 1965 to 1966 and 1966 to 1967 provided an assessment of duck d i s t r i b u t i o n from September to May. A Cessna 180, f i x e d - w i n g , f l o a t -equipped a i r c r a f t was used f o r each census. It was flown at an airspeed of eigh t y to one hundred miles per hour',, and at an a l t i t u d e of one hundred to two hundred f e e t . Airspeed and a l t i t u d e v a r i e d according to weather cond i t i o n s . The census r o u t e , as shown in Figure 2, was followed as o f t e n as weather would permit. Ducks on the t i d a l marshes from lona Island to the Brunswick Hunting Ground were counted f i r s t . This was followed by a count of those in Boundary and Mud Bays. The return t r i p to Sea Island afforded an o p p o r t u n i t y to census ducks on Ladner Marsh and the adjacent upland, and those on the uplands of Westham and R e i f e l I s l a n d s . In January, 1967, a f t e r a s i g n i f i c a n t p r o p o r t i o n of the d e l t a duck population was found to be feeding i n d a y l i g h t hours on the upland areas around Clov e r d a l e and Fry's Corner, the census route was changed to include these a r e a s . The i n t e r v a l between censuses v a r i e d from two weeks to two months during the winter of 1965 to 1966, w i t h ten censuses conducted from September to A p r i l . During the w i n t e r of 1966 to 1967, nineteen censuses F I G U R E 2 THE STUDY AREA AND AERIAL CENSUS ROUTE '3 were made from September to May, at shorter i n t e r v a l s of one to three weeks. Weather and s t a r t i n g time f o r each.census v a r i e d c o n s i d e r a b l y , but as o f t e n as p o s s i b l e , censuses were s t a r t e d when the t i d e on the marshes was r i s i n g from ten feet above sea l e v e l . With t h i s t i d e c o n d i t i o n , ducks were u s u a l l y concentrated along the edge of the water, near the middle l e v e l of the marsh. When the plane flew j u s t to the seaward s i d e of t h i s c o n c e n t r a t i o n , the ducks took f l i g h t , g e n e r a l l y at r i g h t angles to the l i n e of the plane's t r a v e l . This enabled an observer on each s i d e of the plane to estimate the numbers and species composition of the ducks. Most ducks were observed w i t h i n a few hundred yards of the pl a n e , but on a few o c c a s i o n s , they were seen on open water up to one mile from the t i d a l marsh. When t h i s o c c u r r e d , number and species were estimated from the regu l a r l i n e of f l i g h t , or the plane was d i r e c t e d over them f o r a b e t t e r es t i m a t e . The choice of a c t i o n depended on the number of ducks and t h e i r d i s t a n c e from the t i d a l marsh. I n d i v i d u a l ducks were counted in small f l o c k s , but as t h i s was impossible f o r very large c o n c e n t r a t i o n s , gross estimates of numbers were made. The t o t a l number of ducks was recorded at each of the f o l l o w i n g l o c a t i o n s : lona and Sea Islands; Lulu I s l a n d ; R e i f e l and Westham Islands; Brunswick Hunting Ground to Tsawwassen j e t t y ; Boundary Bay; Mud Bay; Cl o v e r d a l e ; Fry's Corner; Ladner Marsh and adjacent upland; and the upland of Westham and R e i f e l I s l a n d s . The method of recording data influenced the observer's accuracy in est i m a t i n g the number of each s p e c i e s . In the f i r s t year (1965 to 1966), numbers were recorded w i t h p e n c i l and paper f o r most of the above u n i t s . A f t e r l a n d i n g , observers j o i n t l y estimated the pro p o r t i o n of each of the 14 four duck species in the t o t a l duck popu l a t i o n over the e n t i r e census r o u t e . These prop o r t i o n s were a p p l i e d to the t o t a l number to provide estimates of the numbers of each s p e c i e s . In the f o l l o w i n g w i n t e r , tape recorders were used to record the numbers and species i d e n t i f i e d . This probably increased the accuracy of the estimates f o r 1966 to 1967. Accuracy in e s t i m a t i n g the numbers and species of ducks from a r a p i d l y moving a i r c r a f t i s dependent on v i s i b i l i t y and observer experience. Speed of the a i r c r a f t , f i e l d of view, and observation d i s t a n c e a f f e c t v i s i b i l i t y . These three f a c t o r s were standardized as much as weather, choice of a i r c r a f t , and duck d i s t r i b u t i o n would permit. L i g h t i n t e n s i t y , however, v a r i e d cons iderabl.y. A sky with a h i g h , l i g h t overcast provided the best c o n d i t i o n s . Bright,sunny weather o f t e n r e s u l t e d in g l a r e from the water's s u r f a c e , and r a i n reduced the observers' a b i l i t y t o , i d e n t i f y species by t h e i r c o l o u r s . Observer experience probably influenced some counts, because several d i f f e r e n t observers were used, and some were inexperienced in a e r i a l censusing of w a t e r f o w l . To overcome t h i s , experienced observers accompanied those l e s s experienced on i n i t i a l f l i g h t s . Thus, inexperienced observers were able to provide comparable r e s u l t s on subsequent f l i g h t s . This technique d i d not provide very accurate counts, but was useful f o r as s e s s i n g r e l a t i v e abundance of each s p e c i e s , and trends in t h e i r p o p u l a t i o n s . As i n d i c a t e d above, census dates v a r i e d c o n s i d e r a b l y between the two w i n t e r s . T h e r e f o r e , in an a l y s i n g and graphing the d a t a , each census was taken as being r e p r e s e n t a t i v e of a two week long p e r i o d . When two censuses were conducted w i t h i n a two week p e r i o d , as in September and October, 1966," 15 an average of t h e i r t o t a l s was taken. This method made i t p o s s i b l e to compare data from both y e a r s . T i d a l marshes o n l y . During waterfowl counts, ducks present on i n d i v i d u a l census u n i t s were recorded. These were l a t e r separated i n t o those present on t i d a l marsh census u n i t s , and those present elsewhere. The percentage of the t o t a l present on the t i d a l marshes was c a l c u l a t e d f o r each census, and a mean percentage was then c a l c u l a t e d f o r each of the two wi n t e r s . Because the percentage of the duck population present on the t i d a l marshes v a r i e d c o nsiderably throughout the two w i n t e r s , and because small numbers of ducks sometimes were afforded equal importance to large numbers, duck numbers were compared rather than percentages. The t o t a l numbers of ducks observed on the t i d a l marshes f o r a l l censuses over both w i n t e r s were then expressed as percentages of the t o t a l numbers of ducks observed over the e n t i r e census r o u t e , f o r a l l censuses and both w i n t e r s . The numbers of ducks recorded on the Brunswick Hunting Ground include those present on the la r g e s a l i n e mud f l a t adjacent to the Tsawwassen j e t t y , as well as those on the t i d a l marsh adjacent to Canoe Pass. During censusing, these two h a b i t a t types were included in the one census u n i t . This has r e s u l t e d in a s l i g h t l y i n f l a t e d f i g u r e f o r the o v e r a l l percentage of ducks present on t i d a l marsh areas. 'Segments of the t i d a l marsh. A e r i a l census data were used to i n d i c a t e the r e l a t i v e importance to the four duck s p e c i e s , of separate segments of the t i d a l marsh. The percentage of the t o t a l p opulation present on each t i d a l marsh u n i t was c a l c u l a t e d f o r both w i n t e r s . Data 1 16 on species occurrence at each segment of the t i d a l marsh were a v a i l a b l e only f o r 1966 to .1967. The percentage of each of the four duck species in the t o t a l , o c c u r r i n g throughout the w i n t e r , was c a l c u l a t e d f o r a l l four t i d a l marsh census u n i t s , s e p a r a t e l y , and c o l l e c t i v e l y . Percentages were determined by summing the number of each species observed over the whole w i n t e r , and expressing i t as a percentage of a l l ducks observed. 11. TIDAL MARSH FEATURES Several features of f i v e t i d a l marsh u n i t s were measured w i t h the a i d of l i n e t r a n s e c t s . Four of these u n i t s received e q u a l l y i n t e n s i v e assessment, but the Sea Island u n i t was studied more e x t e n s i v e l y . In pres e n t i n g the d a t a , R e i f e l Island i s tr e a t e d separately from Westham I s l a n d , although t h e i r t i d a l marshes are almost continuous. ' Area. The t o t a l area of a l l t i d a l marsh u n i t s was determined from a e r i a l photographs with the a i d of a dot area g r i d . The approximate s c a l e of the photographs was one inch to s i x hundred f e e t . On the g r i d , one dot was equal to one-hundredth of one square i n c h . The number of dots on the t i d a l marsh was then converted to square feet and a c r e s . Topography. Topographical r e l a t i o n s h i p s of the t i d a l marsh were revealed by mapping the p o r t i o n s of the marsh covered by t i d e s of known h e i g h t . Throughout the study, the Tide and Current Tables of the Canadian Hydrographic Service were used. These t a b l e s l i s t the times and l e v e l s of the high and low t i d e s f o r each day at Point A t k i n s o n , the nearest reference port to the t i d a l marshes. Thus, i t was p o s s i b l e to c a l c u l a t e the approximate t i d e l e v e l at any time of day and to record l e v e l s between which each p l a n t species grew. Vegetation composi t i o n . A l i n e t r a n s e c t method of sampling v e g e t a t i o n was chosen because i t provided data on several f e a t u r e s of the v e g e t a t i o n , and because i t was a simple and f a i r l y speedy method. Transects began o u t s i d e the dikes at the edge of the marsh v e g e t a t i o n , and ran at r i g h t angles to the d i k e s . Pasture or upland v e g e t a t i o n was omitted from the t r a n s e c t s . A one hundred foot nylon l i n e was p u l l e d t i g h t between two stakes and placed three inches above the ground. Vegetation was pushed a s i d e so that p l a n t s emerging from the ground d i r e c t l y under the l i n e could be i d e n t i f i e d and counted. For each p l a n t s p e c i e s , the frequency of occurrence, d i s t r i b u t i o n , and area covered were o b t a i n e d . To determine frequencies of occurrence, the t o t a l number of plants of each species was recorded f o r each one hundred fo o t sampling u n i t , and these t o t a l s summed f o r the e n t i r e t r a n s e c t . Data from the t r a n s e c t s were summed f o r each t i d a l marsh u n i t , and then f o r a l l the t i d a l marsh u n i t s c o l l e c t i v e l y . Frequency of occurrence was then determined by expressing the t o t a l number of p l a n t s of one species as a percentage of the t o t a l number of pla n t s of a l l s p e c i e s . The d i s t r i b u t i o n of each p l a n t species along each t r a n s e c t was marked on an a e r i a l photograph. A f t e r the tra n s e c t s had been completed, the d i s t r i b u t i o n of plan t species between tr a n s e c t s was determined by reconnaissance. The boundaries of the s i x most abundant species were then marked on a e r i a l photographs and l a t e r p l o t t e d on maps. An estimate of the number of acres occupied by each species was ; ' 18 made from the l i n e t r a n s e c t d a t a . The p e r c e n t a g e o f a l l one hundred f o o t sample u n i t s i n w h i c h each s p e c i e s o c c u r r e d was m u l t i p l i e d by t h e t o t a l a c r e a g e o f t h e t i d a l m a r shes. T h i s method was thought t o be s a t i s f a c t o r y f o r t h e most abundant s p e c i e s . For t h o s e o c c u r r i n g i n f r e q u e n t l y , however, t h e method p r o b a b l y r e s u l t e d i n an e r r o n e o u s l y l a r g e c o v e r a g e . But t h i s o c c u r r e d f o r s p e c i e s o f l i t t l e i m p o r t a n c e t o d u c k s , and t h e e r r o r i s i n c o n s e q u e n t i a l . Duck f o o d p r o d u c t i o n . The p r o d u c t i o n o f seeds from f i v e i m p o r t a n t t i d a l marsh s p e c i e s was d e t e r m i n e d f o r o n l y one y e a r . E i g h t l i n e t r a n s e c t s run i n August and September o f 1966 i n d i c a t e d t he p r o p o r t i o n o f S c i r p u s and E l e o c h a r ? s stems p r o d u c i n g s e e d s . A random sample o f one thousand C a r e x  L y n g b y e i • s t e m s from a l l a r e a s o f t h e marsh i n d i c a t e d t h e p r o p o r t i o n o f p r o d u c t i v e stems f o r t h a t s p e c i e s . The mean number o f seeds produced by a h e a l t h y stem o f each s p e c i e s was d e t e r m i n e d by t a k i n g a random sample o f one hundred o r two hundred p r o d u c t i v e p l a n t s . By m u l t i p l y i n g t h e f r e q u e n c y o f o c c u r r e n c e , t h e p r o p o r t i o n o f p r o d u c t i v e s t e m s , and t h e mean number o f seeds p r o d u c e d , a r e l a t i v e i ndex o f seed p r o d u c t i o n was o b t a i n e d . 111. DUCK FOOD HABITS The ducks used f o r a n a l y s i s o f t h e i r f o o d h a b i t s were c o l l e c t e d f rom August t o A p r i l , a l t h o u g h t he m a j o r i t y were o b t a i n e d d u r i n g t h e r e g u l a r h u n t i n g s e a s o n , O c t o b e r t o J a n u a r y . Ducks were c o l l e c t e d from t h e t i d a l marshes on Westham I s l a n d , Sea I s l a n d , and Ladner M a r s h , and from a d j a c e n t a g r i c u l t u r a l a r e a s on Westham I s l a n d and near C l o v e r d a l e . A d d i t i o n a l l y , a v e r y s m a l l number was t a k e n i n Boundary Bay. 19 The r e l a t i v e importance of i n d i v i d u a l food items in the d i e t was in d i c a t e d by the volume consumed, and by the frequency w i t h which i t was found in crop and g i z z a r d c o n t e n t s . Volumes of items consumed were expressed as percentages of the t o t a l sample, as in the aggregate volume method of Martin et al (19^6). . Volumes were obtained by two methods. P r i o r to a n a l y s i s , large numbers of seeds of several food species were counted, and t h e i r cumulative volumes obtained by water displacement. Average volumes f o r each seed were then a p p l i e d d i r e c t l y to the numbers of seeds counted in each sample to obt a i n t o t a l volume consumed. The average volumes obtained are presented in Appendix 5- Volumes of- animal or v e g e t a t i v e material were obtained by water displacement. Items o c c u r r i n g in volumes too small to r e g i s t e r in a graduated c y l i n d e r were accorded a volume of 0.01 m i l l i l i t r e s . Food items making up l e s s than 0.1 percent of the t o t a l d i e t were excluded from the f i n a l f i g u r e s . Martin (19^3) i n d i c a t e d that volumes of less than one percent are u s u a l l y recorded as t r a c e s . This study includes items w i t h volumes of only 0.1 percent, so that some of the t i d a l marsh species w i t h very low consumed volumes w i l l be included in d i s c u s s i o n . An Importance Value was e s t a b l i s h e d to i n d i c a t e the r e l a t i v e importance of each food item. This Importance Value was the product of the percentage volume and the percentage frequency. From i t , an Importance Index v/as d e r i v e d . The highest Importance Values were scaled down a c c o r d i n g l y to provide Importance I n d i c e s . No Importance Indices l e s s than 0.1 are presented. Importance Values were a l s o used to estimate the importance of 20 ^-each of the feeding areas f o r the four duck s p e c i e s . Feeding areas were c l a s s i f i e d as t i d a l marsh, a g r i c u l t u r a l a r e a s , and inland waters. For each feeding a r e a , the Importance Values of the a p p l i c a b l e food items were summed. The sums were in turn added to produce a grand t o t a l of a l l Importance Values f o r each duck s p e c i e s . The sum of Importance Values f o r each feeding area was then expressed as a percentage of the t o t a l , to i n d i c a t e the importance of that feeding area to the duck s p e c i e s . CHAPTER IV DUCK OCCURRENCE The importance of a p a r t i c u l a r type of duck h a b i t a t may be i n d i c a t e d by the number of ducks o c c u r r i n g on i t . The periods during which ducks are p r e s e n t , and the r e l a t i v e number present are occurrence f a c t o r s which should be known in order to assess importance. Once t h i s has been assessed, the most v a l u a b l e p o r t i o n s of the h a b i t a t may be set a s i d e f o r p r o t e c t i o n and p r e s e r v a t i o n . This s e c t i o n of the study attempts to o u t l i n e the occurrence of ducks on the d e l t a t i d a l marsh h a b i t a t . A e r i a l census of ducks on separate u n i t s of the d e l t a foreshore and adjacent uplands, conducted over two w i n t e r s , provided a measure of the d i s t r i b u t i o n and abundance of four duck s p e c i e s . The data are presented to show the annual population f l u c t u a t i o n s of M a l l a r d , P i n t a i l , Widgeon, and Green-winged T e a l . Since t i d a l marshes form a larg e part of the census a r e a , i t i s l i k e l y that population f l u c t u a t i o n s over the e n t i r e census area are r e p r e s e n t a t i v e of them. The p r o p o r t i o n of ducks o c c u r r i n g on the t i d a l marshes i s presented to i n d i c a t e r e l a t i v e importance to the t o t a l duck p o p u l a t i o n . A d d i t i o n a l l y , the species and r e l a t i v e number of each o c c u r r i n g on four separate segments of the t i d a l marsh are presented i n an attempt to i n d i c a t e which segments are of most v a l u e . 1. DELTA FORESHORE AND ADJACENT UPLANDS The wi n t e r duck population of the d e l t a may be separated i n t o three i n t e r - r e l a t e d seasonal components. The f i r s t of these occurs from l a t e 22 August to l a t e December, and i s here r e f e r r e d to as the f a l l m igrating component. Figures 3 , 4, 5 , and 6 a l l show t h i s component c l e a r l y , and are based on data presented in Appendixes 6 and 7. The second, rather i l l -d e fined component, occurs during January and i s r e f e r r e d to as the w i n t e r i n g component. It represents the low point in the w i n t e r duck populations and i t i s d i f f i c u l t to separate i t from the two other seasonal components. The l a s t of these, the s p r i n g migrating component, occurs from the end of January u n t i l e a r l y May. None of these seasonal population components are s t a t i c . A l l e x h i b i t wide f l u c t u a t i o n s in number, although the two m i g r a t i n g components f l u c t u a t e more than the w i n t e r i n g component. The f a l l m i g r ating component appears, to be the l a r g e s t , as i n d i c a t e d in Figures 3 to 6. This aspect may be more apparent than r e a l , however, and w i l l be discussed in a l a t e r s e c t i o n . Figures 3 to 6 i n d i c a t e s u b s t a n t i a l d i f f e r e n c e s in the s i z e of the populations f o r the two years censused. The a v a i l a b l e data cannot be used to e x p l a i n these d i f f e r e n c e s , but they may be due to increased breeding success, or to delays in m i g r a t i o n , or to both of these f a c t o r s . Timing of m i g r a t i o n i s not completely understood, but i s c e r t a i n l y influenced by weather system's which d i f f e r y e a r l y (Hochbaum, 1955). The general pattern of migration on the d e l t a shown by f l u c t u a t i o n s in numbers seems to be s i m i l a r in both y e a r s , although minor v a r i a t i o n s do o c c u r . A e r i a l counts were not conducted in August, but a few ground observations of ducks on the Sea I s l a n d , Lulu I s l a n d , and R e i f e l Island t i d a l marshes i n d i c a t e d that the duck population had increased from the very low summer numbers by the end of August. A e r i a l counts i n d i c a t e d that the f i r s t FIGURE 3 MALLARD POPULATION FRASER RIVER DELTA 1 9 6 5 - 6 6 1 9 6 6 - 6 7 15,000-1 i 10,000-5,000 M O N T H 25,000-i 20,000-15,000-10,000-5,000-FIGURE 4 PINTAIL POPULATION FRASER RIVER DELTA 1 9 6 5 MONTH FIGURE 5 FRASER RIVER DELTA MONTH FIGURE 6 GREEN-WINGED TEAL POPULATION FRASER RIVER DELTA I 9 6 5 - 6 6 1 9 6 6 - 6 7 I I 15,000 -1 • 10,000-E i S O N D J F M 27 large p o p u l a t i o n increases occurred near the end of September. From October to December, duck numbers remained very high as the f a l l m i g ration proceeded. At the end of December there was a rapid d e c l i n e in the numbers of a l l four s p e c i e s , but p a r t i c u l a r l y in the numbers of P i n t a i l and Green-winged Teal (See Figures h and 6 ) . Ducks remaining in January were r e f e r r e d to as the w i n t e r component and were j o i n e d by those of the s p r i n g migrating component towards the end of that month. From l a t e January to e a r l y March, the t o t a l duck population increased to a peak, followed by a l e s s e r peak in e a r l y A p r i l . A f t e r t h i s p o i n t , the duck population d e c l i n e d s t e a d i l y , dropping sharply at the middle of May. At the end of May only very small numbers of ducks were present on the t i d a l marshes. The species composition of the duck population m i g r a t i n g through and w i n t e r i n g on the d e l t a i s probably dependent on the r e l a t i v e breeding success of each s p e c i e s , and on f a c t o r s a f f e c t i n g t h e i r speed of m i g r a t i o n . These f a c t o r s f l u c t u a t e y e a r l y , so the species composition of the d e l t a ducks must a l s o f l u c t u a t e comensurately. Improved census techniques permitted a more accurate a p p r a i s a l of the composition of the duck population i n I966 to 1967 than were p r e v i o u s l y a v a i l a b l e . Although long-term d i f f e r e n c e s in species composition undoubtedly o c c u r , the more accurate counts show that the populations c o n s i s t e d of 17.8 percent M a l l a r d , 26.1 percent P i n t a i l , 33 .8 percent Widgeon, and 22 .3 percent Green-winged T e a l . These percentages are derived from the t o t a l number of each species observed throughout the w i n t e r , expressed as a percentage of the t o t a l ducks observed. Although the populations of these four duck species e x h i b i t e d comparable f l u c t u a t i o n s , there were some minor d i f f e r e n c e s between them. Population N/1 O rvj T" FIGURE 7 HE TOTAL DUCK POPULATION OCCURRING OH THE TIDAL MARSHES 29 The more accurate census data from 1966 to 1967 show that although Widgeon and Green-winged Teal f i r s t migrated onto the d e l t a in la r g e numbers in l a t e September (See Figures 5 and 6 ) , M a l l a r d and P i n t a i l d i d not appear in large numbers u n t i l October (See Figures 3 and h). Widgeon and Green-winged Teal a l s o appeared to be l a t e r s p r i n g migrants than M a l l a r d and P i n t a i l . The l a r g e s t numbers of sp r i n g migrating M a l l a r d and P i n t a i l appeared in March (See Figures 3 and k), but the Widgeon and Green-winged Teal populations increased u n t i l e a r l y May. A f t e r the middle of May, there was a very abrupt d e c l i n e in t h e i r populations (See Figures 5 and 6 ) . 11. TIDAL MARSH ONLY The pr o p o r t i o n of ducks seen on the t i d a l marsh census u n i t s was determined s e p a r a t e l y f o r each year from the cumulative t o t a l s of a l l ducks observed. In 1965 to 1966, 58.8 percent and in 1966 to 1967, 5k.2 percent of a l l ducks counted were found on the t i d a l marsh census u n i t s , compared to a combined average f o r both years at 55.4 percent. However, the pro p o r t i o n of ducks present on actual t i d a l marsh h a b i t a t was s l i g h t l y l e s s than t h i s because a large area of s a l i n e mud f l a t s used by s u b s t a n t i a l numbers of ducks was included in the Brunswick Hunting Ground u n i t . A b e t t e r estimate of the p r o p o r t i o n of ducks using t i d a l marsh h a b i t a t would be about 50 percent. The complete data f o r these proportions are shown in Appendixes 8 and 9 . The p r o p o r t i o n of ducks present on the t i d a l marshes v a r i e d c o n s i d e r a b l y throughout the two winte r s (See Figure 7 ) . Near the beginning of the f a l l m i g r a t i o n and near the end of the sp r i n g m i g r a t i o n , between 3b • e i g h t y and one hundred percent of the ducks were observed on t i d a l marshes. During i n t e n s i v e migration p e r i o d s , a l a r g e r - p r o p o r t i o n of ducks were seen on Boundary and Mud Bays, so that only t h i r t y to s i x t y percent of the ducks were observed on t i d a l marsh h a b i t a t . During the short w i n t e r i n g p e r i o d , approximately one-half of the ducks used the t i d a l marshes. Data on these proportions were f a i r l y s i m i l a r during both win t e r s (See Figure 7 and Appendixes 8 and 9 ) , and the duck population on the t i d a l marshes e x h i b i t e d s i m i l a r f l u c t u a t i o n s in number as f o r the whole d e l t a . Counts f o r 1966 to 1967 i n d i c a t e that there may be some d i f f e r e n c e s between the t i d a l marsh areas and the remaining census u n i t s , regarding the r e l a t i v e p r o p o r t i o n of the .four duck species o c c u r r i n g on them. The f o l l o w i n g percentages i l l u s t r a t e t h i s : Ma 11ard P i n t a i l Widgeon Green-winged Teal T i d a l Marshes: 16.2 13.1 41.9 - 28.8 E n t i r e Census Route: 17.8 26.1 33.8 22.3 Although the four duck species can be seen on a l l census u n i t s , the above data suggest that the t i d a l marshes may be r e l a t i v e l y more a t t r a c t i v e to Widgeon and Green-winged T e a l , and l e s s a t t r a c t i v e to P i n t a i l . M a l l a r d showed no p a r t i c u l a r preference f o r the t i d a l marshes. 111. SEGMENTS OF THE TIDAL MARSH The percentage of the t o t a l duck population present'on each of the four census u n i t s in the t i d a l marsh v a r i e d w i t h i n and between both w i n t e r s . The data presented in Appendixes 10 and 11 i n d i c a t e that v a r i a t i o n w i t h i n w i n t e r s was the greater of the two. The f o l l o w i n g percentages i n d i c a t e that 3i; . v a r i a t i o n between the two w i n t e r periods was minor: lona and Lulu R e i f e l and Brunswick Sea I si a rids I s 1 and Westham Is! aiids Hunt i ng Ground 1965- 66: 24.3 20.4 34.4 20.9 1966- 67: . 21.9 25.8 27.5 24.8 The R e i f e l and Westham Islands census u n i t seemed to a t t r a c t s l i g h t l y more ducks than each of the other three u n i t s . This may have been due to the presence of the George C. R e i f e l V/aterfowl Refuge on R e i f e l I s l a n d . The other three u n i t s a t t r a c t e d s i m i l a r numbers, although the lona and Sea Islands u n i t is s l i g h t l y smaller i n area than the other two. Notably, the Brunswick Hunting Ground u n i t , at l e a s t two-thirds of which i s covered by s a l i n e mud f l a t s , a t t r a c t e d s i m i l a r numbers of ducks as d i d the other t i d a l marsh are a s . These data i n d i c a t e that a l l four t i d a l marsh census u n i t s are of f a i r l y equal importance to ducks. Although each of the four t i d a l marsh census u n i t s a t t r a c t e d s i m i l a r t o t a l numbers of ducks, the r e l a t i v e abundance of the four duck species d i f f e r e d f o r each u n i t . Data from the 1966 to 1967 censuses l i s t e d the numbers of each of the four duck species o c c u r r i n g on each u n i t , and o c c u r r i n g on the t o t a l t i d a l marsh census a r e a . These data are presented in Appendixes 12 through 16. Cumulative percentages c a l c u l a t e d for each species and census u n i t f o r that winter appear in Table 1. They suggest that species d i s t r i b u t i o n on the t i d a l marshes during 1966 to 1967 was not random. The r e l a t i v e occurrence of each species on each t i d a l marsh census u n i t d i f f e r e d from that on the e n t i r e t i d a l marsh area. On lona and Sea I s l a n d , there were more Green-winged Teal and l e s s P i n t a i l . Lulu Island had more Widgeon and l e s s M a l l a r d . R e i f e l and Westham Islands a t t r a c t e d more Mallard and P i n t a i l , 32 TABLE 1 CUMULATIVE PERCENTAGES OF OCCURRENCE OF FOUR DUCK SPECIES COUNTED AT EACH OF FOUR TIDAL MARSH CENSUS UNITS DURING THE WINTER OF V966 TO I967 Census U n i t M a l l a r d P i n t a i l Widgeon Green-winged T e a l lona and Sea I s l a n d s : 16.2 6.0 44.7 33.1 L u l u I s l a n d : 6.1 13.5 53.9 26.5 R e i f e l and • Westham I s l a n d s : 30.1 18.3 30'.7 20.9 Br u n s w i c k H u n t i n g Ground: 9.5 12.9 41.2 36.4 T o t a l o f f o u r t i d a l marsh census u n i t s : , 16.2 13.1 41.9 28.8 33 and l e s s Widgeon and Green-winged T e a l . On Brunswick Hunting Ground there were more Green-winged Teal and l e s s M a l l a r d . The reasons f o r t h i s apparently non-random d i s t r i b u t i o n remain obscure. With data from only one y e a r , and no estimate of v a r i a t i o n in the d a t a , s i g n i f i c a n t d i f f e r e n c e s in species i d i s t r i b u t i o n cannot be demonstrated. W. CONCLUSIONS The preceding data on duck occurrence a l l o w some t e n t a t i v e c o n clusions to be drawn, as f o l l o w s : 1. The times during which maximum duck numbers are present on the t i d a l marshes are the f a l l and s p r i n g m igration p e r i o d s , from October to December, and from February to A p r i l . 2. More ducks are observed on the t i d a l marshes during the f a l l m i g r a t i o n , p a r t i c u l a r l y in November, than during the s p r i n g m i g r a t i o n . , 3. There are annual v a r i a t i o n s in the s i z e of the populations of each of the four duck species observed on the t i d a l marsh. k. A l l four census u n i t s of the t i d a l marsh a t t r a c t f a i r l y equal win t e r t o t a l s of ducks, although the r e l a t i v e number at each u n i t may vary throughout the w i n t e r . 5. The t i d a l marshes as a whole appear to a t t r a c t approximately one-half of a l l the ducks observed on the Fraser d e l t a . CHAPTER V TIDAL MARSH FEATURES The f a c t that the t i d a l marshes a t t r a c t ducks has long been recognized by l o c a l hunters and n a t u r a l i s t s . The r e s u l t s of the a e r i a l censusing f u r t h e r e s t a b l i s h t h i s f a c t . Ducks use the t i d a l marshes as l o a f i n g and feeding a r e a s , w i t h emphasis on l o a f i n g (Benson, 1 9 6 4 ) . If the t i d a l marshes are to be improved so that they a t t r a c t even more ducks, some information on t h e i r p h y s i c a l and b i o l o g i c a l f e a t u r e s must be known. The features most deserving of study are suggested from the few references a v a i l a b l e on the- Fraser d e l t a . Previous s t u d i e s of the food habits of the four duck species (Munro, 1 9 3 9 , 1943, ' 1 9 4 9 a , 1 9 4 9 b ) , ( C o t t l e , 1949) i n d i c a t e that much of t h e i r food c o n s i s t s of seeds from v a r i o u s p l a n t s . Since the ducks are known to be feeding on the t i d a l marshes, i t is d e s i r a b l e to know something about the composition, d i s t r i b u t i o n , and r e l a t i v e food production of the plant species growing t h e r e . This s e c t i o n attempts to provide such i n f o r m a t i o n . S o i l and water on the t i d a l marshes have been d e s c r i b e d , but a d d i t i o n a l information on the extent and topography of the t i d a l marshes w i l l be presented. Information on the composition and d i s t r i b u t i o n of the p l a n t species is provided from a s e r i e s of l i n e t r a n s e c t s . The r e l a t i v e food production by the most abundant species is i n d i c a t e d from l i n e t r a n s e c t s and samples of seeds from i n d i v i d u a l p l a n t s . Line t r a n s e c t s and a e r i a l photographs reveal the extent of the t i d a l marshes, and topographical r e l a t i o n s h i p s are noted from general reconnaissance. 35 1 . EXTENT AND TOPOGRAPHY The extent of the t i d a l marshes determined from a e r i a l photographs and l i n e t r a n s e c t s , was approximately 3,733 a c r e s . This area probably increases s l i g h t l y each y e a r , as a d d i t i o n a l sediments are d e p o s i t e d . The f i v e separate u n i t s are of d i f f e r e n t size's and c o n t r i b u t e the f o l l o w i n g approximate percentages to the t o t a l area: Lulu I s l a n d , k0%; R e i f e l I s l a n d , 20%; Westham I s l a n d , 20%; Brunswick Hunting Ground, 10?; lona and Sea I s l a n d s , 10%. The average width of the t o t a l t i d a l marsh, measured from the dikes to the edge of the v e g e t a t i o n , i s j u s t over one-half m i l e , but t h i s width d i f f e r s f o r each unit-. The t i d a l marsh is narrowest at lona and Sea I s l a n d s , averaging j u s t under o n e - t h i r d of a m i l e , and widest on R e i f e l Island where i t s t r e t c h e s seaward f o r more than three-quarters of a m i l e . At Lulu I s l a n d , Westham I s l a n d , and Brunswick Hunting Ground, the t i d a l marsh v a r i e s in width between one-half and three-quarters of a m i l e . The topography slopes g e n t l y from an e l e v a t i o n at the base of the dikes e q u i v a l e n t to a twelve or t h i r t e e n foot t i d e , to an e l e v a t i o n at the seaward edge of the vegetation equivalent to a seven fo o t t i d e . The steepness of t h i s slope v a r i e s c o n s i d e r a b l y . On the northernmost p o r t i o n s of Lulu and Westham I s l a n d s , the o v e r a l l slope i s of f a i r l y uniform steepness. At most other l o c a t i o n s , however, there i s a sudden "drop-off" somewhere in the marsh. Figure 8 i l l u s t r a t e s two marsh p r o f i l e s w i t h " d r o p - o f f s " . The sudden decrease in e j e v a t i o n occurs most commonly around the ten foot t i d e l e v e l , and g e n e r a l l y runs p a r a l l e l to the dikes and the edge i.ooo 2,000 Distance from Dike (feet) 3 , 0 0 0 4 , 0 0 0 Tide Level (feet) Lulu Island - North L e g e n d C.L. Carex Lyngbyei T.I. Typha l a t i f o l i a S.ac. Scirpus acutus S.p. Scirpus paludosus S.v. Scirpus validus S. a. Scirpus americanus FIGURE 8 REPRESENTATIVE TIDAL 1ARSH PROFILES SHQWBUG THE 37 of the v e g e t a t i o n . Within a h o r i z o n t a l d i s t a n c e of f i v e to ten f e e t , the e l e v a t i o n of the marsh may be reduced by s i x to eighteen inches. The ex i s t e n c e of t h i s marked change i n e l e v a t i o n permits the v i s u a l separation of the t i d a l marsh i n t o an upper and a lower zone, each d i s p l a y i n g a somewhat d i f f e r e n t v e g e t a t i v e composition. The upper zone of the t i d a l marsh l i e s between the t h i r t e e n and ten foot t i d e l e v e l s . It i s u s u a l l y g e n t l y s l o p i n g w i t h some small humps and depressional a r e a s , and i s drained by an i n t r i c a t e maze of narrow, shallow channels which e v e n t u a l l y u n i t e to form f a i r l y large d i t c h e s d r a i n i n g out to sea. The lower zone li.es between the ten and seven foot t i d e l e v e l s . L i k e the upper zone, i t has a gentle s l o p e , but there are u s u a l l y a great many humps and depressional a r e a s . The drainage pattern c o n s i s t s of wide, g e n e r a l l y shallow d i t c h e s , w i t h few of the smaller channels found on the upper zone. 11. VEGETATION COMPOSITION AND DISTRIBUTION Fourteen plant species occur on the t i d a l marshes, most of them on a l l f i v e u n i t s . Two of these s p e c i e s , a sedge, Carex Lyngbyei, and a three-square b u l l rush, Sci rpus americanus, comprise 70% of a l l the pl a n t s on the Marshes (See T a b l e l l ) . Carex Lyngbyei i s , w i t h two p o s s i b l e e x c e p t i o n s , the dominant species on the upper zone of the marsh. Scirpus americanus i s the dominant species on the lower zone. The ranges of these two species overlap along the border of the upper and lower zones (See Table 111). With the exception of a few s o l i t a r y s p e c i e s , l o c a l l y growing in dense stands, TABLE 11 THE PLANT SPECIES COMPOSITION ON FIVE UNITS OF THE FRASER RIVER TIDAL MARSHES EXPRESSED AS PERCENT FREQUENCY, AND THE ACREAGE COVERED BY EACH PLANT SPECIES Percent Frequency Confidence L i m i t s Brunswi ck Hunting Westham R e i f e l Lulu lona/Sea Total . Lower Upper Species Ground Island Island Island Island Marsh J L i m i t L i m i t Acreage Scirpus americanus 56. .8 38.5 28.7 69.7 74.4 51. ,0, 40.9 61.2 2,960 Carex Lyngbyei 22. .0 21.3 36.5 7.6 8.3 19. .0 11.1 26.9 1 ,500 El e o c h a r i s macrostachya 17. .2 19-0 19.4 * 0.7 11. ,4 6.0 16.7 1 ,860 Scirpus paludosus 1. .2 0.1 17.9 10.3 6. .5 2.3 10.8 900 Sci rpus val idus 7.9 8.1 1.7 2.4 4. .7 2.7 6.8 1,635 T r i g loch in maritima 0. .7 4.2 3.0 1.7 1.2 2. .6 1.5 3.6 1,500 Juncus b a l t i c u s 5.3 0.5 * 1 .0 1 . .8 0.4 3.2 175 Typha 1 at i f o l i a j 1.1 1.4 0.2 0.7 0. ,8 0.3 •1.3 455 Sag i t t a r ia l a t i f o l i a 1 . .3 1.1 1.3 - - 0. .7 0.2 1 .2 645 Potent i l i a Egedei 'c 0.5 0.4 0.9 0.6 0. 5 0.2 • 0.8 290 Scirpus acutus 0.4 * 0.3 0.4 0. 2 - 0.5 75 Bidens cernua 0. .7 0.2 0.2 - 0. .2 - 0.5 430 Si urn sauve 0.3 0.2 - - 0. . 1 ' - 0.2 360 Alisma t r i v i a l e < 0.4 * - - 0. 1 - 0.2 195 "Percent frequency less than 0.1% CO TABLE 111 SOME HABITAT CHARACTERISTICS OF THE TIDAL MARSH PLANTS Tide Level Species Zone Range (Ft.) S i t e Scirpus americanus Upper, Lower 11; h to 7 Wet, depress ional Carex Lyngbyei Upper, Lower '.' 13 to 9i " Well drained E l e o c h a r i s macrostachya Upper, Lower 13 to 7 Wet, depress ional Scirpus paludosus Upper, Lower 11: ir to 7 Wet, depress iona1 Sci rpus v a l i d u s Upper, Lower 12 to 7 Wet, depress ional T r i g loch in maritima Upper, Lower 13 to 8 Wei 1 drained Juncus b a l t i c u s Upper 13 to 11 Well drained Typha l a t i f o l i a Upper 13 to 10 Wet, depress ional S a g i t t a r i a l a t i f o l i a Upper, Lower 13 to 8 Wet, depress ional Potent i l i a Egedei Upper 13 to 11 Well drained Sci rpus acutus Upper 13 to 11 Wet, depress iona1 Bidens cernua Upper 13 to 11 Wei 1 dra i ned Sium sauve Upper 13 to 10 Wei 1 dra i ned A l i sma t r iv ia1e Upper, Lower 13 to 8 Wet, depress iona1 ho a l l other species are interspersed among Carex Lyngbyei and Sci rpus  amer icarius. The upper zone of the t i d a l marsh supports a l l fourteen species shown i n Tables 11 and 111. I t ' s approximate a r e a , determined from the extent of Carex Lyngbyei, Typha 1 at i f o l i a, and Sci rpus a c u t u s , shown in Table 1 1 , i s 50% of the t i d a l marsh, or about 1,860 a c r e s . Carex Lyngbyei , g e n e r a l l y o c c u r r i n g on w e l l - d r a i n e d s i t e s , i s the dominant species on the upper zone. However, the common c a t t a i l , Typha 1 a t i f o l ? a , and the hard roundstem b u l l r u s h , Scirpus acutus, both of which occur on wet, depressional s i t e s , form dense stands in which Carex Lyngbye? seldom grows. In the absence of these two densely growing s p e c i e s , Carex Lyngbyei grows in a continuous band from the base of the dikes at the twelve to t h i r t e e n f o o t t i d e l e v e l to the nine and one-half foot t i d e l e v e l j u s t below the " d r o p - o f f " . Of the two densely growing species in the upper zone, Sci rpus  acutus appears to be unable to withstand much submergence. It grows from the base of the dikes down only to the eleven foot t i d e l e v e l . . Typha l a t i f b l i a apparently i s able to withstand more submergence, and grows from the base of the d i k e as f a r down the marsh as the ten foot t i d e l e v e l . The remaining species on the upper zone occur int e r s p e r s e d among Carex Lyngbyei, some on we l l - d r a i n e d s i t e s , and others in wet depressions. F i v e species are inte r s p e r s e d among Carex Lyngbyei on w e l l - d r a i n e d s i t e s . Two species of minor importance, Juncus b a l t i c u s , or common rush, and Potent?11a Eqedei , or c i n q u e f o i l , grow from the base of the dikes only as low as the eleven foot t i d e l e v e l . Another two species of e q u a l l y minor status are Bidens cernua, or beggar's t i c k , and Si urn sauve, or water p a r s n i p . These h] two species occur from the base of the dikes down to the ten foot t i d e l e v e l . A f i f t h species growing on w e l l - d r a i n e d s i t e s i s ' T r i g l o c h i n maritima or arrowgrass. This species occurs on both upper and lower zones, from the base of the dikes down to the eight foot t i d e l e v e l . The other s i x species recorded on the upper zone grow most commonly in wet d e p r e s s i o n s , and occur a l s o on the lower zone of the t i d a l marsh. Three of these s p e c i e s , S a g i t t a r i a l a t i f o l i a or arrowhead, Alisma  t r i v i a l e or water p l a n t a i n , and Eleochar?s macrostachya or s p i k e r u s h , are of minor importance. The f i r s t two of these three species grow between the base of the dike and the eight foot t i d e l e v e l . The t h i r d spec i e s , El eochar i s  macrostachya, grows from the base of the dike out to the edge of the v e g e t a t i o n , at the seven foot t i d e l e v e l . The l a s t three more abundant species are b u l l rushes. Sci rpus v a l i d u s , the s o f t roundstem b u l l rush, grows from the twelve f o o t t i d e l e v e l down to the seven foot t i d e l e v e l . The other two b u l l rush s p e c i e s , Scirpus paludosus, or l e a f y three-square b u l l r u s h , and Scirpus americanus, or three-square b u l l r u s h , grow from the eleven and one-h a l f foot t i d e l e v e l down to the seven foot t i d e l e v e l . The lower zone of the t i d a l marsh which makes up the remaining 50% or 1,860 acres supports only e i g h t of the fourteen plant species l i s t e d in Table 11. Carex Lyngbyei and T r i g l o c h i n maritima most f r e q u e n t l y occur on r a i s e d , w e l l - d r a i n e d humps. The bul1 rush species (S. americanus, S. paludosus, and v a 1 i d u s ) , Eleochar i s macrostachya, Sagi t t a r i a ' 1 at i f o l i a , and Alisma  t r i v i a l e a l l occur on wetter depressional s i t e s . Sci rpus americanus i s the dominant species and a l l other species are interspersed among i t , at l e a s t to some degree. Sci rpus v a l i d u s and Scirpus paludosus o c c a s i o n a l l y form 42 f a i r l y dense stands which i n h i b i t the growth of Sci rpus amer i canus. The composition and d i s t r i b u t i o n of the veget a t i o n v a r i e s f o r each of the f i v e t i d a l marsh u n i t s . This i s i l l u s t r a t e d in Figures 9 to 13 and i n Table 11. On each u n i t the frequency of occurrence of a s i n g l e species i s determined by the t o t a l number of species o c c u r r i n g and the r e l a t i v e abundance of each. A d d i t i o n a l l y , i t i s determined by the environmental c o n d i t i o n s which p r e v a i l over each t i d a l marsh u n i t . Five of the species mapped in Figures 9 to 13 and some of the less abundant s p e c i e s , show marked d i f f e r e n c e s in d i s t r i b u t i o n . The frequency of occurrence and d i s t r i b u t i o n of Carex Lyngbyei and Scirpus americanus vary f o r each u n i t . Scirpus americanus i s more abundant than Carex Lyngbyei on a l l u n i t s except R e i f e l I s l a n d . However, on R e i f e l and Westham Islands and Brunswick Hunting Ground, Carex Lyngbye? i s much more abundant than i t i s on the remaining t i d a l marsh u n i t s . I t i s the dominant species on the upper zone of the marsh w h i l e Scirpus americanus i s the dominant species on the lower zone. The simplest explanation f o r the v a s t l y d i f f e r e n t frequencies encountered, i s that there i s more Carex Lyngbyei wherever there i s a l a r g e r p r o p o r t i o n of upper zone. Since Sea, lona, and Lulu Islands have a smaller p r o p o r t i o n of upper zone than the other three u n i t s , Carex Lyngbye? has a small e r frequency of occurrence. Conversely, Scirpus americanus has a l a r g e r frequency of occurrence because the pro p o r t i o n of lower zone i s l a r g e r at Sea, lona, and Lulu I s l a n d s . Two other species which e x h i b i t marked v a r i a t i o n s in frequency of occurrence are Sci rpus va1idus and Sci rpus pa 1udosus. Sci rpus va1idus i s most abundant on R e i f e l and Westham I s l a n d s , and much less abundant on the FIGURE 9 Distribution Of Predominant Tidal Marsh Species FIGURE 10 Distribution Of Predominant Tidal Marsh Species Legend Scirpus americanus • Scirpus validus mi Sci rpus paludosus Scirpus acutus Carex Lyngbyei — — i i Typha latifol ia e9 | | | | | xttr Westham Island Approx imate Sca le Lulu Island - South | 2000 Feet | Approximate Scale FIGURE I I Distribution Of Predominant Tidal Marsh Spec ies 1967 Legend Sci rpus amer icanus Sc i rpus validus Sc i rpus pa ludosus Sc i rpus acutus C a r e x Lyngbye i Typha lat i fol ia FIGURE 12 stribution Of Predominant Tidal Marsh Spec ies 1967 [ 2000 Feet j Approximate Sca le Legend Scirpus americanus Scirpus validus Scirpus paludosus Scirpus acutus y// \ m Carex Lyngbyei Typha latifolia v • * m •*•*•*« FIGURE 13 Distr ibut ion Of Predominant Tidal Ma rsh S p e c i e s ' '< • 48 other three u n i t s . Conversely, Sci rpus paludosus i s most abundant on Sea, lona, and Lulu I s l a n d s , and on Brunswick Hunting Ground. It occurs hardly at a l l on R e i f e l and Westham I s l a n d s . These two species grow between almost the same t i d e l e v e l s (See Table 111), but with the exceptions of small areas on Lulu and Sea I s l a n d s , they r a r e l y grow on the same s i t e . The l a s t of the important species shown in Figures 9 to 13, which e x h i b i t s a marked v a r i a t i o n i n d i s t r i b u t i o n , i s the c a t t a i l , Typha l a t i f o l i a . This i s most abundant on R e i f e l and Westham I s l a n d s , o c c u r r i n g much le s s abundantly on the other three u n i t s . In a d d i t i o n to the f i v e species mentioned above, there are f i v e l e s s abundant species which a l s o show d i f f e r e n c e s in d i s t r i b u t i o n . These are: E l e o c h a r i s macrostachya, S a g i t t a r i a 1 a t ? f o l i a , Bidens'cernua, S i urn sauve, and Alisma t r i v i a l e . A l l of these species occur more abundantly on R e i f e l and Westham Islands than on the other three u n i t s . From the data presented above, i t appears that R e i f e l and Westham Islands provide b e t t e r h a b i t a t f o r a l l fourteen p l a n t species than do the remaining t i d a l marsh u n i t s . 111. RELATIVE DUCK FOOD PRODUCTION Fiv e p l a n t species were chosen f o r a determination of t h e i r duck food producing c a p a b i l i t y . These species were Sc i rpus amer icanus, Carex  Lyngbyei, E l e o c h a r i s macrostachya, Sc ? rpus paludosus, and Sc? rpus va1i dus . They were chosen because of t h e i r recognized value as duck food plants and because they were the most abundant species on the t i d a l marshes, t o t a l i n g 92.S% of a l l the p l a n t s . These species were though to be adequately r e p r e s e n t a t i v e of the p r o d u c t i v i t y of the e n t i r e t i d a l marsh, p a r t i c u l a r l y in view of the low frequencies of occurrence of the remaining nine s p e c i e s . The production of seeds by these f i v e species d i f f e r e d c o n s i d e r a b l y between the two zones. The upper zone appeared to be much more productive than the lower zone, thereby i n d i c a t i n g that seed production was influenced by e l e v a t i o n and the degree of t i d a l f l o o d i n g . This apparent r e l a t i o n s h i p d i f f e r e d s l i g h t l y f o r each of the f i v e s p e c i e s . Carex Lyngbyei produced seeds f a i r l y uniformly between the t h i r t e e n and ten foot t i d e l e v e l s , but not a l l stems produced seeds. Below the ten foot t i d e l e v e l , no stems produced seeds. E l e o c h a r i s macrostachya was unproductive throughout most of i t s range. None of the t r a n s e c t s revealed productive p l a n t s , but a few areas were found between the t h i r t e e n and twelve foot t i d e l e v e l s where t h i s species produced mature seed heads with seeds. Between the twelve and ten foot t i d e l e v e l s no seeds were produced, but there was a gradient in seed head development. At the higher end of t h i s g r a d i e n t , near the twelve foot t i d e l e v e l , p l a n t s developed seed heads which progressed only to the p o l l i n a t i o n stage. Further down the g r a d i e n t , only t i n y undeveloped seed heads were formed. Around the ten foot t i d e l e v e l , p l a n ts did not develop seed heads, and t h i s c o n d i t i o n p r e v a i l e d over the e n t i r e lower zone of the t i d a l marsh. Most stems of Scirpus paludosus produced seeds between the eleven and one-half and ten foot t i d e l e v e l s . Between the ten and nine foot t i d e l e v e l s , stems e x h i b i t e d a gr a d i e n t in seed head fo r m a t i o n . Near the ten foot l e v e l they developed normal seed heads c o n t a i n i n g small numbers of seeds. P r o g r e s s i v e l y , towards the lower end of the g r a d i e n t , they formed p o l l i n a t i n g seed heads with no seeds, then only t i n y undeveloped seed heads, and f i n a l l y , below the nine foot t i d e 1 e v e l , seed.heads d i d not develop. Scirpus americanus seed production was almost i d e n t i c a l in d i s t r i b u t i o n and degree to that of Sc i rpus pa 1udosus. Seed production by Scirpus v a l i d u s d i f f e r e d from the other two Sc? rpus s p e c i e s . Between the twelve and ten foot t i d e l e v e l s n early a l l stems produced seeds normally. Between the ten and seven foot t i d e l e v e l s they e x h i b i t e d a gradient in seed head development. This gradient was much more obvious than in Scirpus paludosus or Scirpus americanus because of the greater v a r i a t i o n i n stem height shown by Sc?rpus va1idus. Just below the ten foot t i d e l e v e l the sho r t e r stems did not produce seeds, but formed p o l l i n a t i n g seed heads. T a l l e r stems were s t i l l p r o d u c t i v e . Between the ten and seven f o o t t i d e l e v e l s , p r o g r e s s i v e l y fewer stems produced seeds. At the seven foot t i d e l e v e l , only the t a l l e s t stems, those above f i v e f e e t , produced seeds. A l l other stems were unproductive and e x h i b i t e d a v e r t i c a l gradient in seed head development s i m i l a r to the other two Scirpus s p e c i e s . By l a t e August, the stems of El e o c h a r i s and Scirpus which had not produced seeds were yellowed and w i l t i n g , w h i l e productive stems appeared normal. A l l stems of Carex Lyngbyei appeared normal, whether productive or n o t . Samples of productive seed heads from these f i v e species were c o l l e c t e d on the highest l e v e l s of the marsh in 1966, in order to o b t a i n a maximum estimate of seed production from what was suspected to be a poor seed production year. The mean number of seeds produced by each appears in Table IV. Notably, the f i f t h most abundant s p e c i e s , Sc i rpus va1i dus , was 51 TABLE IV SEED PRODUCTION BY HEALTHY SEED HEADS OF THE FIVE MOST ABUNDANT PLANT SPECIES ON THE FRASER DELTA TIDAL MARSHES IN 1966 Mean Number of 95? Confidence L i m i t s Seeds ± Standard on the Mean Number of Species Deviation Seeds Sci rpus v a l i d u s 370 + 25 320 to 419 Carex Lyngbyei 218 + 8 202 to 233 Scirpus paludosus 113 + 11 91 to 134 E l e o c h a r i s macrostachya 18 + 1 16 to 20 Scirpus americanus 14 + 1 13 to 16 ' 52 the most pr o d u c t i v e species when c o n s i d e r i n g seed production from i n d i v i d u a l stems. This was followed in decreasing order of seed production by Carex  Lyngbyei, Sc? rpus paludosus , and Eleochar i s macrostachya. Sc i rpus amer icanus, the most abundant s p e c i e s , was the l e a s t p r o d u c t i v e . The percentage of Sci rpus and E l e o c h a r i s stems producing seeds was determined from l i n e t r a n s e c t d a t a . A random sample of one thousand Carex  Lyngbyei stems i n d i c a t e d the p r o p o r t i o n of productive stems f o r that s p e c i e s . The data appear in Table V. The most productive species by pr o p o r t i o n of seed-producing stems i s , a g a i n , Sci rpus v a l i d u s . Notably, t h i s i s the species which due to i t s height i s l e a s t flooded by d a i l y t i d e s . The pro p o r t i o n of productive stems f o r the other s p e c i e s , a l l of which are submerged to a greater e x t e n t , i s much l e s s . Production by Eleochar i s macrostachya, as i n d i c a t e d above, i s very low, but some productive stems were found. In order to compare the p r o d u c t i v i t y f o r these f i v e s p e c i e s , three separate p r o d u c t i v i t y f a c t o r s were m u l t i p l i e d t o g e t h e r , and t h e i r product expressed as an index. The mean number of seeds produced by one healthy p l a n t , the percentage of productive stems, and the frequency of occurrence, when combined f o r each s p e c i e s , y i e l d e d the ind i c e s presented in Table VI. Sc i rpus  va1idus was the most productive p l a n t , followed c l o s e l y i n order by Carex  Lyngbyei. The two other Scirpus species were, almost e q u a l l y , much le s s p r o d u c t i v e . E l e o c h a r i s macrostachya had a seed production index of z e r o , but a c t u a l l y produced a very small q u a n t i t y of seeds. 53 TABLE V Spec ies THE PERCENTAGE OF STEMS PRODUCING SEEDS FOR THE FIVE MOST ABUNDANT PLANT SPECIES ON THE FRASER DELTA TIDAL MARSHES IN 1966 Percentage of Productive Stems Sc? rpus v a l i d u s  Carex Lyngbyei Sci rpus paludosus Sci rpus amer icanus 16.8 5.3 4.3 3.1 E l e o c h a r i s macrostachya 0.0 TABLE VI SEED PRODUCTION INDICES FOR THE FIVE MOST ABUNDANT PLANT SPECIES ON THE FRASER DELTA TIDAL MARSHES IN 1966 Species Seed Production Index Scirpus v a l i d u s - 100 Carex Lyngbyei ,, 75 Sci rpus paludosus 11 Sci rpus amer icarius 8 Eleochar?s macrostachya 0 55 IV. CONCLUSIONS The preceding data on t i d a l marsh features a l l o w some conclusions to be drawn, as f o l l o w s : 1. T i d a l marsh vegetation covers approximately 3,733 a c r e s , of which the f i v e t i d a l marsh u n i t s c o n t r i b u t e the f o l l o w i n g approximate percentages: Lulu I s l a n d , h0%; R e i f e l I s l a n d , 20?; Westham I s l a n d , 20?; Brunswick Hunting Ground, 10?; lona and Sea I s l a n d s , 10?. 2. The width of the t i d a l marsh, from the base of the dike to the edge of the v e g e t a t i o n , averages j u s t over one-half m i l e . It is narrowest at lona and Sea I s l a n d s , where i t i s j u s t under o n e - t h i r d of a m i l e , and widest at R e i f e l I s l a n d , where i t is j u s t over three-quarters of a m i l e . 3. The topography of the t i d a l marsh slopes g e n t l y from the twelve to t h i r t e e n foot t i d e l e v e l at the base of the dikes to the seven foot t i d e l e v e l a t the edge of the v e g e t a t i o n . h. An abrupt decrease in e l e v a t i o n of s i x to eighteen inches, u s u a l l y occurs near the ten foot t i d e l e v e l in a l i n e roughly p a r a l l e l to the d i k e s . This separates the marsh i n t o an upper and lower zone, each developing d i f f e r e n t v e g e t a t i v e cover. 5. Two Cyperaceae spec ies , Sc ? rpus amer icanus and Carex Lyngbyei , representing 70? of a l l t i d a l marsh p l a n t s , are the dominant species on the lower zone and upper zone r e s p e c t i v e l y . ' 56 6. Another three Cyperaceae spec i e s , ET eochar i s macrostachya, Sci rpus paludosus, and Sci rpus v a l i d u s , when added to the two dominant s p e c i e s , represent 92.6% of a l l the t i d a l marsh p l a n t s . 7. An a d d i t i o n a l nine species from d i f f e r e n t p l a n t f a m i l i e s increase the t o t a l number of species found on the t i d a l marsh to f o u r t e e n . 8. The l o c a l d i s t r i b u t i o n of most of the t i d a l marsh p l a n t s i s probably i n f l u e n c e d , at l e a s t in p a r t , by the degree of t i d a l f l o o d i n g and by the degree of drainage from the s i t e . c 9. The 1966 seed production by the f i v e most abundant species was confined almost e n t i r e l y to the upper zone of the t i d a l marsh. 10. The success of seed production by the Eleochar i s and Sc? rpus species appeared to be determined, at l e a s t in p a r t , by the degree of t i d a l f l o o d i n g of the seed head. 11. The pr o p o r t i o n of productive stems of the f i v e most abundant ' species was very low, w i t h Scirpus v a l i d u s a c h i e v i n g 16.8% and the others approximately 5% or l e s s . 12. Of the f i v e most abundant t i d a l marsh p l a n t s studied in the summer of 1966, Scirpus v a l i d u s produced the l a r g e s t q u a n t i t y of seeds, followed c l o s e l y , in o r d e r , by Carex Lyngbyei and less c l o s e l y by Sci rpus pa 1udosus and Sci rpus americanus, w h i l e the f i f t h spec i es , Eleocha r i s macrostachya , produced very few seeds. CHAPTER VI DUCK FOOD HABITS • Previous chapters have shown the r e l a t i v e importance of the Fraser d e l t a t i d a l marshes to w i n t e r i n g ducks and have d e a l t with some of the f e a t u r e s of t h i s h a b i t a t . This information suggests that a l l segments of the t i d a l marsh are of f a i r l y equal value and that they might a l l be preserved and protected i n order to maintain waterfowl populations on the d e l t a . However, those f e a t u r e s which could most l i k e l y be improved upon remain undetermined. Ducks use the t i d a l marshes as l o a f i n g and feeding s i t e s . It seems l i k e l y , then, that the value of these marshes might be enhanced by managing them to favour the growth of those p l a n t species of greatest importance as food and cover. Local hunters and n a t u r a l i s t s have noted that the ducks spend a great deal of t h e i r time l o a f i n g and feeding over flooded v e g e t a t i o n . I t i s probably safe to conclude, t h e r e f o r e that the t i d a l marsh p l a n t s are more important in p r o v i d i n g the ducks with food than they are in p r o v i d i n g c o v e r . With the above c o n s i d e r a t i o n s i n mind, t h i s p o r t i o n of the study w i l l attempt to reveal the r e l a t i v e importance of some of the t i d a l marsh pl a n t species i n p r o v i d i n g food f o r ducks. A study of the winter d i e t of each of the four duck species on the d e l t a i s one means of accomplishing t h i s t a s k . The a n a l y s i s of the combined contents of crops and g i z z a r d s from ducks c o l l e c t e d on the t i d a l marshes, or on the adjacent a g r i c u l t u r a l a r e a s , 58 provided data on the r e l a t i v e importance of i n d i v i d u a l food items. Since hunting success on the t i d a l marshes was rather low, approximately one-half the sample was c o l l e c t e d on c l o s e l y adjacent a g r i c u l t u r a l areas where hunting success was g r e a t e r . Food items from both areas were commonly found in i n d i v i d u a l ducks. The importance values of food items taken on each feeding area were summed to provide an estimate of the importance of each one. With only two e x c e p t i o n s , there was no d i f f i c u l t y in determining from which feeding area a food item had been taken. Some of the u n i d e n t i f i e d m a t e r i a l , and the seeds of common rush, Juncus sp., were a v a i l a b l e on both a g r i c u l t u r a l and t i d a l marsh a r e a s . It was decided a r b i t r a r i l y that 70% of the u n i d e n t i f i e d v e g e t a t i v e m a t e rial was taken on a g r i c u l t u r a l areas and 30% taken on the t i d a l marshes. For Juncus sp. seeds, i t was decided that equal amounts were taken from the two feeding areas. While these a r b i t r a r y d e c i s i o n s may have r e s u l t e d in some degree of e r r o r , i t is f e l t that t h i s i s minimal. This chapter provides data on several aspects of the winte r d i e t of M a l l a r d , P i n t a i l , Widgeon, and Green-winged T e a l . The q u a n t i t i e s of food consumed on both important feeding a r e a s , and the pr o p o r t i o n of ducks c o l l e c t e d on them i s di s c u s s e d . The r e l a t i v e importance of the most commonly eaten t i d a l marsh food items, which is the primary o b j e c t i v e of t h i s p o r t i o n of the study, i s i n d i c a t e d . A d d i t i o n a l l y , the importance of the most commonly eaten a g r i c u l t u r a l area food items i s noted. Unless otherwise noted, a l l food items r e f e r r e d to are seeds. An estimate of the importance of each feeding area to each duck species i s pr o v i d e d , based on the sum of importance values f o r each feeding area. 59 During the course of i d e n t i f y i n g and-sorting food m a t e r i a l s , the number of ducks which had ingested lead shot was noted. This information is presented in Appendix 17. Data from other b i o l o g i s t s studying lead poisoning of Fraser d e l t a ducks i s presented in Appendix 18, in a d d i t i o n to the data from t h i s study. 1. MALLARD FOOD HABITS The general l o c a t i o n s from which the 189 M a l l a r d used f o r food h a b i t s a n a l y s i s were c o l l e c t e d are given in Appendix k. Most of the ducks were l a b e l l e d w ith the exact c o l l e c t i o n a r e a , but some from Westham Island were not, so the probable area of c o l l e c t i o n was obtained by examining the types of food material consumed. It i s estimated that f i f t y - f o u r percent of the sample was c o l l e c t e d on the t i d a l marshes and that the remaining f o r t y - s i x percent was c o l l e c t e d on a g r i c u l t u r a l areas. The t o t a l volume of food material analysed from the g i z z a r d s and crops of the 189 M a l l a r d amounted to 3^1.53 m i l l i 1 i t r e s , an average volume of 1.81 m i l l i1 i t res per duck. Approximately one-half the M a l l a r d g i z z a r d s sampled contained l e s s than one m i l l i l i t r e of food. The maximum volume contained by one g i z z a r d was 7.20 m i l l M i t r e s , w h i l e the maximum volume contained by one crop was 51.60 m i l l M i t r e s . ' The temporal and s p a t i a l d i s t r i b u t i o n of M a l l a r d which were found to c o n t a i n more than one m i l l i l i t r e of food in both g i z z a r d and crop is n o t a b l e . In September, e a r l y October, Late January, February, and March, Ma l l a r d c o l l e c t e d on the t i d a l marsh were f r e q u e n t l y found to have moderately large q u a n t i t i e s of food in both crop and g i z z a r d . Those 60 c o l l e c t e d on the t i d a l marsh from l a t e October to e a r l y January very o f t e n contained no food in the crop and very small volumes in the g i z z a r d . M a l l a r d s -c o l l e c t e d on a g r i c u l t u r a l areas from l a t e October to e a r l y January g e n e r a l l y contained l a r g e r volumes of food material in both crop and g i z z a r d than those c o l l e c t e d on the t i d a l marsh during the same p e r i o d . It may be that the t i d a l marshes do not provide equal feeding opportunity to M a l l a r d as do the a g r i c u l t u r a l areas during the l a t e October to e a r l y January p e r i o d . . This a n a l y s i s of M a l l a r d w i n t e r food habits revealed seventeen food items of importance. Eleven of these were a v a i l a b l e on the t i d a l marshes, four were a v a i l a b l e on a g r i c u l t u r a l a r e a s , and one item was a v a i l a b l e from both areas.. The remaining item, seeds of sago pondweed, Potamogeton p e c t i n a t u s , was a v a i l a b l e in freshwater sloughs and d i t c h e s , although t h i s species grows on the t i d a l marshes as w e l l . The r e l a t i v e importance of a l l these items i s i n d i c a t e d in Appendix 19. The t i d a l marsh food items in order of t h e i r importance to Mallard were: Carex Lyngbye? ; Sci rpus v a l i d u s ; and Scirpus americanus (see Figure 14). Other less important t i d a l marsh items in order of t h e i r importance value i n c l u d e d : u n i d e n t i f i e d v e g e t a t i v e m a t e r i a l ; Alisma  t r i v i a l e ; E l e o c h a r i s macrostachya; buckbean, Menyanthes t r i f o l i a t a , a wetland species from Ladner Marsh; Si urn sauve; T r i g l o c h i n maritima; horned pondweed, Z a n n i c h e l l i a p a l u s t r i s , an aquatic found on some t i d a l marsh un i t s ; Potent i l l a Egedei; and r i c e c u t g r a s s , L e e r s i a o r y z o i d e s , a grass species thought to have been obtained from the Ladner Marsh a r e a . Although f i v e items in the winte r d i e t of M a l l a r d were obtained from a g r i c u l t u r a l a r e a s , only one of these, Polygonum spp.(P. l a p a t h i f o l i u m Corex Lyngbyei Scirpus validus j Scirpus americanus Other Agricultural Area Food Items Unidentified Vegetative Material Other Tidal Marsh Food Items Alisma triviale T I D A L M A R S H F O O D I T E M S A G R I C U L T U R A L A R E A F O O D I T E M S FIGURE 14 THE RELATIVE IMPORTANCE* OF FOOD ITEMS IN THE WINTER DIET OF MALLARD FROM THE FRASER DELTA TIDAL M A R S H E S * * ^Relative importance is indicated by an importance value, which is the product of the percent volume and the percent frequency for each food item. * *Ba sed on a pooled sample of 341.53 ml. obtained from the crops and gizzards of 189 Mallard collected on or adjacent to the tidal marshes from August to April, 1965-1966 and 1966-1967. 62 and P. pers i c a r ia) was of any importance. As the seeds of these two species were d i f f i c u l t to d i s t i n g u i s h , they were considered as one item. The l e s s important items from a g r i c u l t u r a l areas i n c l u d e : u n i d e n t i f i e d v e g e t a t i v e m a t e r i a l ; mi 11et, Ech inochloa crusgal1? ; ragweed, Ambros i a a rtemi s i ? f o l i a ; and s a l t b u s h , Atr i p i ex patu1 a. As i l l u s t r a t e d in Figure 14, t h i s sample of 189 M a l l a r d i n d i c a t e s that the t i d a l marshes are of greater importance than the a g r i c u l t u r a l areas in p r o v i d i n g w i n t e r food (see a l s o Appendix 20). However, t h i s i s a very small sample i n terms of the M a l l a r d p o p u l a t i o n , and the volumes of food m a t e r i a l analysed from each specimen were g e n e r a l l y rather s m a l l . It is probably unwise, t h e r e f o r e , to t r e a t these data as c o n c l u s i v e evidence that the t i d a l marshes are most important as a provider of winter food f o r M a l l a r d . 11. PINTAIL FOOD HABITS The c o l l e c t i o n areas of the n i n e t y - e i g h t P i n t a i l used f o r food habits a n a l y s i s are recorded in Appendix h. Some P i n t a i l from Westham Island were not l a b e l l e d and the exact area of c o l l e c t i o n was determined from the food material they had consumed. It i s estimated that f i f t y - t w o percent of the sample was c o l l e c t e d on the t i d a l marshes, w h i l e the remaining f o r t y - e i g h t percent was c o l l e c t e d on a g r i c u l t u r a l areas. The t o t a l volume of food material analysed from the n i n e t y - e i g h t P i n t a i l amounted to 185.69 m i l l i l i t r e s , an average of 1.90 ml 1 1 1 1 i t r e s . Approximately one-half the g i z z a r d s contained less than one m i l l i 1 11re of food. Maximum volumes of food material found in g i z z a r d and crop were 4.55 63 mi 1 1 i 1 i t r e s and hi.25 m i l l i l i t r e s , r e s p e c t i v e l y . Those P i n t a i l found to c o n t a i n moderate to large q u a n t i t i e s of food material were c o l l e c t e d at s i m i l a r times and from the same l o c a t i o n s as the Ma l l a r d c o n t a i n i n g l a r g e r q u a n t i t i e s of food. For P i n t a i l a l s o , i t appears that the t i d a l marshes may not provide equal feeding o p p o r t u n i t i e s as do the a g r i c u l t u r a l a r e a s , f o r the l a t e October to e a r l y January p e r i o d . At other times, however, the t i d a l marshes appear to o f f e r greater feeding opportunity than do the a g r i c u l t u r a l areas. The a n a l y s i s of food material from the n i n e t y - e i g h t P i n t a i l i n d i c a t e d nineteen food items of some importance. Nine of these items were a v a i l a b l e on the t i d a l marshes, eig h t were a v a i l a b l e on a g r i c u l t u r a l a r e a s , and the remaining two items were a v a i l a b l e on both areas. The r e l a t i v e importance of each item i s i n d i c a t e d in Appendix 21. T i d a l marsh food items in order of importance to P i n t a i l were: Carex Lyngbyei; Scirpus v a l i d u s ; and Sci rpus americanus (see Figure 15). Other l e s s important t i d a l marsh items in order of t h e i r importance value included: u n i d e n t i f i e d v e g e t a t i v e m a t e r i a l ; Scirpus paludosus; T r i g l o c h i n  mar i tima; Eleochar ?s macrostachya; Menyanthes t r i f o l i a t a ; Potent?11 a  Egedei; Si urn sauve; and Juncus spp. , probably J . b a l t i c u s . Of the ten items consumed on the a g r i c u l t u r a l a r e a s , only two appeared to be of any importance to P i n t a i l (see Figure 15). These items were Polygonum spp. , i n c l u d i n g P_. 1 apath i f ol ium and P. pers i c a r i a , and u n i d e n t i f i e d v e g e t a t i v e m a t e r i a l . Other l e s s important food items from a g r i c u l t u r a l areas i n c l u d e d , in order of t h e i r importance value: Echinochloa c r u s g a l l i ; spurry Spergula arvens i s; water f o x t a i l , Alopecurus T I D A L M A R S H F O O D I T E M S A G R I C U L T U R A L A R E A F O O D I T E M S FIGURE 15 T H E R E L A T I V E I M P O R T A N C E * O F FOOD I T E M S IN T H E W I N T E R D IET O F P INTA IL F R O M T H E F R A S E R D E L T A T IDAL M A R S H E S * * ^Relative importance is indicated by an importance value, which is the product of the percent volume and the percent frequency for each food item. **Based on a pooled sample of 185.69 ml. obtained from the crops and gizzards of 98 Pintail collected on or adjacent to the tidal marshes from September to March, 1965 - 1966 and 1966- 1967. 65 • gen i c u l atus ; A t r ip 1 ex patu 1 a; two other Polygonum species , P_. convolvul us and P_. a v i c u l a r e ; c l o v e r , T r i f o l i u m pratense; and Juhcus spp. , probably J_. e f f u s u s . Figure 15 i n d i c a t e s that the t i d a l marshes are of greater importance to P i n t a i l as a feeding area than are the a g r i c u l t u r a l areas (see a l s o Appendix 2 2 ) . However, as wi t h M a l l a r d , the sample s i z e and the volumes of food material analysed f o r P i n t a i l are rather s m a l l . The data are not of s u f f i c i e n t q u a n t i t y on which to base such a c o n c l u s i o n . 111. WIDGEON FOOD HABITS The 115 Widgeon used f o r a n a l y s i s of food h a b i t s are l i s t e d in Appendix k, in a d d i t i o n to the general area from which they were c o l l e c t e d . A number c o l l e c t e d on Westham Island were improperly l a b e l l e d , so the exact c o l l e c t i o n area of these ducks was determined from the food material they contained. On t h i s b a s i s i t i s estimated that t h i r t y - s e v e n percent of the Widgeon were c o l l e c t e d on the t i d a l marsh and s i x t y - t h r e e percent were c o l l e c t e d on a g r i c u l t u r a l areas. This sample of 115 Widgeon provided 35^- 55 m i l l i l i t r e s of food f o r a n a l y s i s , an average of 3 . 0 8 m i l l i l i t r e s f o r each b i r d . Approximately one-half contained l e s s than one m i l l i l i t r e in the g i z z a r d . However, a large p r o p o r t i o n of those c o n t a i n i n g over one m i l l i l i t r e in the g i z z a r d were found to co n t a i n food in the crop as w e l l . Maximum volumes f o r a Widgeon g i z z a r d and crop were k.GO m i l l i l i t r e s and 15-20 m i l l i l i t r e s , r e s p e c t i v e l y . Widgeon c o n t a i n i n g the l a r g e r volumes of food were most f r e q u e n t l y c o l l e c t e d on the t i d a l marsh from l a t e January to A p r i l , or on 66 the a g r i c u l t u r a l areas from October to e a r l y January. U n f o r t u n a t e l y , no Widgeon were c o l l e c t e d in September. The a s s o c i a t i o n of Widgeon c o l l e c t e d on a g r i c u l t u r a l areas and Widgeon c o n t a i n i n g l a r g e r volumes of food was marked. Only a few Widgeon c o l l e c t e d on the t i d a l marsh contained lar g e volumes of food. It appears that the a g r i c u l t u r a l areas provide a greater feeding opportunity f o r Widgeon during the October to January p e r i o d , than do the t i d a l marshes. The food material obtained from the 115 Widgeon revealed only eleven separate items. S i x of these were a v a i l a b l e on a g r i c u l t u r a l a r e a s , four were a v a i l a b l e on the t i d a l marshes, and one was a v a i l a b l e on both areas. The r e l a t i v e importance of these food items i s provided in Appendix 2 3 . T i d a l marsh food items, as i n d i c a t e d i n Figure 16, d i d not appear to be important in the d i e t of the Widgeon sampled. Only two items, u n i d e n t i f i e d v e g e t a t i v e material and Carex Lyngbye? were of great enough importance to appear i n Figure 16. The other even l e s s important items were: Sc? rpus amer?canus; Sci rpus val idus; and Eleochar i s macrostachya. Three of the items consumed on a g r i c u l t u r a l areas were of g r e a t e s t importance (see Figure 1 6 ) . A l l three c o n s i s t e d of green veg e t a t i o n as f o l l o w s : winter r y e , Lolium sp.; u n i d e n t i f i e d Gramineae s p e c i e s ; and other u n i d e n t i f i e d v e g e t a t i v e m a t e r i a l . The l e s s important a g r i c u l t u r a l area food items not appearing in Figure 16 i n c l u d e : leaves and stems of c l o v e r , Tr ? f o l ium sp. ; and seeds from Polygonum spp. (P. lapath i f o l ? urn and P_. pers i car i a ) ; bentgrass, A g r o s t i s s t o l o n i f e r a ; and A t r ? p i ex pa t u l a . The a n a l y s i s i n d i c a t e s that the a g r i c u l t u r a l areas are of greater Lolium sp. Vegetation Other Tidal Marsh Food Items -Carex Lyngbyei Unidentified Vegetative Material Other Agricultural Area Food Items Unidentified Vegetative Material T I D A L M A R S H A G R I C U L T U R A L A R E A F O O D I T E M S F O O D I T E M S FIGURE 16 THE RELATIVE IMPORTANCE* OF FOOD ITEMS IN THE WINTER DJET OF WIDGEON FROM T H E FRASER DELTA TIDAL MARSHES** *Relotive importance is indicated by an importance value, which is the product of the percent volume and the percent frequency for each food item. * *Based on a pooled sample of 354.55 ml. obtained from the crops and gizzards of 115 Widgeons collected on or adjacent to the tidal marshes from October to April, 1965-1966 and 1966-1967. 68 importance f o r feeding than are the t i d a l marshes (see a l s o Appendix 2k). This may well be the case, because Widgeon p r e f e r green v e g e t a t i o n over seeds, and the t i d a l marshes provide very l i t t l e green vegetation during the w i n t e r . However, the sample s i z e f o r Widgeon i s f a i r l y s m a l l , and t h i s c o n c l u s i o n requires other supporting evidence before i t can be considered v a l i d . IV. GREEN-WINGED TEAL FOOD HABITS The c o l l e c t i o n areas of the 75 Green-winged Teal used f o r a n a l y s i s are recorded in Appendix k. A number of b i r d s c o l l e c t e d on Westham Island were improperly l a b e l l e d , however, so t h e i r exact c o l l e c t i o n area was determined from the food material they had consumed. Approximately f i f t y percent of the sample was taken on the t i d a l marshes, and the remainder taken on the a g r i c u l t u r a l areas. The 75 Green-winged Teal provided a t o t a l volume of 15.10 m i l l f l i t res of food material f o r a n a l y s i s , an average volume of 0.20. m i l l i i i t r e s per b i r d . Maximum volumes f o r a Green-winged Teal g i z z a r d and crop were 0.58 m i l l i 1 f t res and 7.80 mi 1 1 i l I t r e s , ' r e s p e c t i v e l y . Nearly one-h a l f the sample contained l e s s than 0.20 m i l l M i tr e s in the g i z z a r d . It i s d i f f i c u l t to determine from the volumes of food consumed, which of the two feeding areas provided the greater feeding opportunity f o r Green-winged T e a l . Only o n e - f i f t h of the Teal sampled contained more than one m i l l i 1 T t r e of food m a t e r i a l . Those c o n t a i n i n g more were c o l l e c t e d p r i m a r i l y on a g r i c u l t u r a l areas from October to February. However, as the sample s i z e f o r Green-winged Teal i s very s m a l l , i t does not seem 69 a p p r o p r i a t e to attempt drawing any conclusions in t h i s r egard. The a n a l y s i s of Green-winged Teal food habits revealed that nineteen food items were of some importance to t h i s s p e c i e s . Seven of these items were a v a i l a b l e from t i d a l marshes, ten were a v a i l a b l e on a g r i c u l t u r a l a r e a s , and the remaining two items were a v a i l a b l e on both areas. The r e l a t i v e importance of these food items i s i n d i c a t e d in Appendix 25. F i v e of the eight t i d a l marsh items appeared to be f a i r l y important in the d i e t of the green-winged t e a l . These i n c l u d e d , in order of importance: Sci rpus americanus; Sc? rpus v a l i d u s , Carex Lyngbyei; u n i d e n t i f i e d v e g e t a t i v e m a t e r i a l ; and E l e o c h a r i s macrostachya (see Figure 1 7 ) . Other t i d a l marsh items of l e s s e r importance in the d i e t included: Juncus spp. , (probably J_. bal t i c u s ) ; Menyanthes t r i f o l i a t a ; T r i g l o c h ? n  mar ? t ima; and Potent i l i a Egede ?. Of the twelve food items from a g r i c u l t u r a l a r e a s , only two appeared to be of any importance (see Figure 1 7 ) . These were Polygonum spp. (P_. l a p a t h i f o l ium and P_. p e r s i c a r i a ) , and u n i d e n t i f i e d v e g e t a t i v e m a t e r i a l . Other l e s s important items included: Spergula arvens i s; p l a n t a i n , PIantago  major; Juncus spp. , (probably J_. effusus) ; Polygonum av icu 1 are; b u t t e r c u p , Ranunculus repens; T r i f o l i u m repens; Echinochloa c r u s g a 1 1 i ; T r i f o l i u m sp.; Ambrosia a r t e m i s i i f o l i a ; and b l a c k b e r r y , Rubus spp. (R. l a c i n i a t u s and R_. p r o c e r u s ) . The data presented in Figure 17, and in Appendix 26, seem to i n d i c a t e that the t i d a l marshes and a g r i c u l t u r a l areas are of equal importance as feeding areas f o r Green-winged T e a l . This may a c t u a l l y be the c a s e , but s i n c e the sample s i z e and food volumes analysed are so s m a l l , T I D A L M A R S H F O O D I T E M S A G R I C U L T U R A L A R E A F O O D I T E M S FIGURE 17 THE R E L A T I V E IMPORTANCE* OF FOOD ITEMS IN THE WINTER DIET OF GREEN-WINGED T E A L FROM THE F R A S E R DELTA TIDAL M A R S H E S * * *Relat ive importance is indicated by an importance value, which is the product of the percent volume and the percent frequency for each food item. * * B a s e d on a pooled sample of 15.10 ml. obtained from crops and gizzards of 75 Green-winged Teal col lected on or adjacent to the tidal marshes from September to March, 1965-1966 and 1966-1967. no c o n c l u s i o n can s a f e l y be drawn from these d a t a . V. CONCLUSIONS 71 The preceding data on Fraser d e l t a duck food habits a l l o w some t e n t a t i v e conclusions to be drawn as f o l l o w s : 1. M a l l a r d , P i n t a i l , and Green-winged Teal appear to have s i m i l a r food h a b i t s , consuming seeds from the most abundant t i d a l marsh p l a n t s , and from weed species found on a g r i c u l t u r a l areas. 2. Widgeon appear to consume p r i m a r i l y v e g e t a t i v e p o r t i o n s of various Gramineae species found on the a g r i c u l t u r a l a r e a s , t a k i n g only very small q u a n t i t i e s of v e g e t a t i v e p o r t i o n s and seeds from the most abundant t i d a l marsh p l a n t s . 3. The t i d a l marsh food items which appear to be of importance to a l l four s p e c i e s , are the seeds from Carex-Lyngbyei, Sc? rpus va1idus , and Sc? rpus americanus. k. The food items from a g r i c u l t u r a l areas which appear to be of importance to a l l four species are the seeds from Polygonum l a p a t h ! f o l i urn and Polygonum pers i c a r i a. 5- Winter r y e , (Lolium sp.) , and several u n i d e n t i f i e d grass species appear to be of gr e a t e s t importance to Widgeon. 6. A g r i c u l t u r a l areas may provide greater feeding o p p o r t u n i t i e s f o r a l l four duck s p e c i e s , f o r the l a t e October to e a r l y January p e r i o d , than do the t i d a l marshes. CHAPTER V l l DISCUSSION The data presented suggest that t i d a l marshes probably play an important r o l e i n maintaining duck populations on the Fraser d e l t a . However, i t remains to be determined whether or not the t i d a l marshes are of c r i t i c a l importance in maintaining duck p o p u l a t i o n s . That i s , would t h e i r d e s t r u c t i o n r e s u l t i n the duck population by-passing the de l t a ? And f u r t h e r , i f they are of c r i t i c a l importance, or are l i k e l y to become of c r i t i c a l importance, which features could most r e a d i l y be improved to make the t i d a l marshes even more a t t r a c t i v e to ducks? It i s the purpose of t h i s p o r t i o n of the study to sy n t h e s i z e the p r e v i o u s l y presented d a t a , in a d d i t i o n to general observations made during the course of the study, and those data provided by other r e s e a r c h e r s , in order to provide some answers to the above q u e s t i o n s . P r i o r to answering these q u e s t i o n s , however, there are some aspects of the data which merit d i s c u s s i o n in order to c l a r i f y them, or i n d i c a t e t h e i r v a l i d i t y . 1. DUCK OCCURRENCE The census data provided reasonable estimates of the t o t a l numbers and the pro p o r t i o n of each species in the p o p u l a t i o n . One of the l i m i t a t i o n s to these types of d a t a , however, i s that they are s t a t i c . They i n d i c a t e population s i z e and s t r u c t u r e f o r one day o n l y . Even the graphs showing seasonal populations only roughly i n d i c a t e the changes in that p o p u l a t i o n . For example, a net decrease of ten thousand mallard from one census to the next, may be the r e s u l t of several major or minor population f l u c t u a t i o n s , and not the simple decrease i n d i c a t e d . There i s no simple method of i l l u s t r a t i n g the population turnover which probably o c c u r s . The actual number of ducks passing through the Fraser d e l t a on f a l l and s p r i n g migrations i s not known, but can be estimated from a v a i l a b l e d a t a . The t h i r t e e n year averages (1954 to 1966) f o r the P a c i f i c Flyway States (United States Department of the I n t e r i o r , 19&7) i n d i c a t e d January populations f o r each of the four duck species were.as f o l l o w s : M a l l a r d , 2,024,000; P i n t a i l , 2 ,063,000; Widgeon, 1,012,000; and Green-winged T e a l , 277,000. This provides a t o t a l of 5,376,000 ducks. Many of these pass through the Fraser d e l t a on t h e i r way to northern n e s t i n g grounds i n B r i t i s h Columbia, A l b e r t a , Yukon T e r r i t o r y , and Alaska (Munro, 1 9 4 3 , 1 9 4 4 , 1949a, 1949b). It would probably be safe to estimate that at l e a s t one m i l l i o n of these pass through the Fraser d e l t a a r e a . From t h i s information i t i s apparent that a e r i a l counts from t h i s study underestimated the magnitude of the migrating p o p u l a t i o n s . In a s i m i l a r manner, they probably do not a c c u r a t e l y i n d i c a t e the r e l a t i v e s i z e of f a l l and s p r i n g migrating p o p u l a t i o n s . The a e r i a l census data show annual f l u c t u a t i o n s in the s i z e and species composition of the duck p o p u l a t i o n . This f e a t u r e was noted by Munro ( 1 9 4 3 , 1 9 4 4 , 1 9 4 9 a , 1949b) and Benson ( 1 9 6 4 ) . A e r i a l counts of January populations in past years are presented in Appendix 27 to i l l u s t r a t e the f l u c t u a t i o n s in population s i z e . The mean population was 39,670 with a high of 105,080 in I96I and a low of 5,860 in 1959-74 Populations of 11,920 in 1966 and 9,735 in 1967 were below average. Periods of deep snow, o c c u r r i n g i r r e g u l a r l y from year to year in January, may be r e s p o n s i b l e f o r some of the annual v a r i a t i o n o c c u r r i n g during t h i s month. Annual v a r i a t i o n s in other months may not have been as g r e a t , but undoubtedly o c c u r r e d . Causes of the annual f l u c t u a t i o n s i n p o p u l a t i o n and species composition would probably i n c l u d e : v a r i a t i o n s 'in species p r o d u c t i v i t y ; v a r i a t i o n s i n weather patterns before and during m i g r a t i o n ; and v a r i a t i o n s in a t t r a c t i v e n e s s of h a b i t a t along the m i g r a t i o n r o u t e . 11. TIDAL MARSH FEATURES Those features of the t i d a l marsh which deserve f u r t h e r d i s c u s s i o n i n c l u d e the d i s t r i b u t i o n of the plant s p e c i e s , and the apparently v a r i a b l e annual seed p r o d u c t i o n . D i s t r i b u t i o n of plant s p e c i e s . It was suggested p r e v i o u s l y that the d i s t r i b u t i o n of marsh p l a n t s was a f f e c t e d by the degree of t i d a l f l o o d i n g and drainage. However, chemicals in s o i l and water are known to have a strong i n f l u e n c e on the development of c e r t a i n species and may have played a r o l e in the d i s t r i b u t i o n of p l ants on the t i d a l marsh. The data on water s a l i n i t y presented by the P a c i f i c Oceanography Group (1951) suggests there are d i f f e r e n c e s in the s a l i n i t y of water f l o o d i n g d i f f e r e n t t i d a l marsh u n i t s . At h i g h : t i d e s , the s a l t water f r o n t i s much c l o s e r to Sea, l o n a , and Lulu I s l a n d s , and to the Brunswick Hunting Ground, than i t i s to Westham and R e i f e l I s l a n d s . These d i f f e r e n c e s in water s a l i n i t y probably r e s u l t in comparable v a r i a t i o n s in s o i l s a l i n i t y . 75 There are several aspects of the d i s t r i b u t i o n of plant species which i n d i c a t e a response to d i f f e r e n c e s in water and s o i l s a l i n i t y . R e i f e l and Westham I s l a n d s , w i t h p o s s i b l y the lowest s a l i n i t y , support more s p e c i e s , produce the most extensive growth of Typha l a t i f o l i a and Sc ? rpus  va1idus, and grow very l i t t l e Scirpus paludosus compared to the other marsh u n i t s . Benson (1967) a l s o noted that R e i f e l and Westham Islands and Ladner Marsh supported more species than the other t i d a l marsh u n i t s . He suggested that the other u n i t s were more s a l i n e , and could not support some of the species found on the f r e s h e r t i d a l marsh areas. Typha 1 at i f o l i a and Sci rpus v a l i d u s are p r i m a r i l y freshwater species ( F e r n a l d , 1950). J e f f r e y (19^9) reported that on the Skagit d e l t a Typha l a t i f o l i a grows only in freshwater areas. Benson (1961) found that t h i s species died out on lona Island when the new d i k e cut o f f the supply of f r e s h water, a l l o w i n g more s a l i n e water to f l o o d the a r e a . The d i s t r i b u t i o n °f Sci rpus v a l i d u s on the Fraser d e l t a t i d a l marshes a l s o appears to be a s s o c i a t e d w i t h l e s s s a l i n e water c o n d i t i o n s . It i s very scarce on the Brunswick Hunting Ground, and occurs on only the extreme south and north ends of Lulu I s l a n d , and on the south end of Sea Island adjacent to the arms of the Fraser River (see Figures 8 to 12)- The remainder of these three u n i t s may be flooded by more s a l i n e water, thereby preventing t h i s species from growing. Sc? rpus paludosus is well known as a plant of s a l i n e or a l k a l i n e areas (Unger, 1966), and J e f f r e y (19^9) noted that on the Skagit d e l t a i t grew best on lower, more s a l i n e areas. It seems probable that a s i m i l a r 76 growth p a t t e r n p r e v a i l s on the Fraser d e l t a , r e s t r i c t i n g , f o r the most p a r t , the growth of Sci rpus paludosus to the Brunswick Hunting Ground, L u l u , Sea, and lona I s l a n d s . Annual seed p r o d u c t i o n . The production of seeds during 1966 was confined almost e n t i r e l y to the upper zone of the marsh above the ten foot t i d e l e v e l . With the except ion of Carex Lyngbyei, which produced seeds only on the upper zone, the species studied e x h i b i t e d a gradient in f l o r a l development and seed pr o d u c t i o n . There was p r o g r e s s i v e l y les s production and development toward the lower l e v e l s of the marsh. This i n d i c a t e d a r e l a t i o n s h i p between seed production and degree of t i d a l f l o o d i n g of the f l o r a l p a r t s . The only comparable data on seed production on t i d a l marshes comes from J e f f r e y ' s (1349) work on the Skagit d e l t a . He noted that seed production was gre a t e s t on the middle l e v e l s of the marsh, where the great e s t i n t e r s p e r s i o n of plant species o c c u r r e d . The c o n d i t i o n s described are comparable to the areas between the nine to eleven foot t i d e l e v e l s on the Fraser d e l t a . J e f f r e y i n d i c a t e d that Scirpus americanus, o c c u r r i n g on the lowest l e v e l s , never produced seeds. Observations made during three summers i n d i c a t e that t h i s i s a l s o the case on the Fraser d e l t a . On the basis of observed d i f f e r e n c e s in the d i s t r i b u t i o n and pr o p o r t i o n of productive p l a n t s during 1965, 1966, and 1967, i t seems l i k e l y that the seed production i n d i c e s c a l c u l a t e d f o r I966 (see Table V l ) do not adequately represent long term seed p r o d u c t i o n . With t h i s in mind, i t is a p p r o p r i a t e to e s t a b l i s h more accurate long term seed production i n d i c e s f o r each pl a n t s p e c i e s . 77 An accurate a p p r a i s a l of the percentage of productive stems was obtained for the f i v e most important species in 1966, by means of l i n e t r a n s e c t s . The data are presented in Table V. In 1967, w h i l e mapping the d i s t r i b u t i o n of p l a n t s , an estimate of the percentage of productive stems was made. It was estimated at that time that production in 1965 was l e s s than that of 1967 by approximately twenty per cent. These data are combined in Table VI1 to o b t a i n a three-year average of the percentage of productive stems f o r the f i v e s p e c i e s . On a long term b a s i s , Sc? rpus  va1idus i s s t i l l the most productive s p e c i e s , w h i l e a l l f i v e species appear much more productive than i n I966. An approximation of a long term seed production index f o r each of these species i s obtained by m u l t i p l y i n g together the f o l l o w i n g : the three-year average percentage of productive stems presented in Table V l l ; the I966 estimate of mean number of seeds produced by a s i n g l e p l a n t (see Table I V ) ; and the frequency of occurrence of each species determined f o r 1965 and I966 (see Table 1 1 ) . Their product i s expressed as an index, with the highest number r e c e i v i n g an index of 100. The long term seed production i n d i c e s derived are presented in Table V l l l . They i n d i c a t e that Sci rpus v a l i d u s and Carex Lyngbyei are almost e q u a l l y important as seed producers, with Scirpus americanus running a d i s t a n t t h i r d . The two remaining species are much le s s p r o d u c t i v e . These i n d i c e s are based on s u b j e c t i v e estimates of seed p r o d u c t i o n , which are subject to an indeterminable degree of e r r o r . However, in s p i t e of t h i s e r r o r , they are l i k e l y to be more r e p r e s e n t a t i v e of long term seed production than are the data for 1966 a l o n e . 78 TABLE V l l THE THREE-YEAR AVERAGE PERCENTAGE OF PRODUCTIVE STEMS, OF THE FIVE MOST ABUNDANT PLANT SPECIES ON THE FRASER DELTA TIDAL MARSH FROM I965, 1966, AND 1967 Sc i rpus Sc i rpus Carex Eleochar i s Sc i rpus Year va1idus americanus Lyngbye? macrostachya paludosus 1965 68.0 36.0 28.0 20.0 8 .0 1966 16 .8 3.1 5-3 0 . 0 4 .3 1967 85.0 45.0 35.0 25.0 10.0 Three-year Average 56.6 28.0 22.8 15.0 7-4 79 TABLE V l l I ESTIMATED LONG-TERM SEED PRODUCTION INDICES FOR THE FIVE MOST ABUNDANT PLANT SPECIES ON THE FRASER DELTA TIDAL MARSHES Spec i es Long-Term Seed Production Index Sci rpus va1idus Carex Lyngbye ? Sc? rpus amer icanus Sci rpus pa 1udosus E l e o c h a r i s macrostachya 100.0 96.0 20.3 5.5 3.1 111. RELATIVE IMPORTANCE OF THE TIDAL MARSHES AND AGRICULTURAL AREAS The purpose of t h i s study has been to provide information on the importance and c h a r a c t e r i s t i c s of the t i d a l marshes as they r e l a t e to ducks. In the course of compiling t h i s i n f o r m a t i o n , however, i t has become c l e a r that the t i d a l marshes are only one of two important h a b i t a t types on the Fraser d e l t a . The a g r i c u l t u r a l areas are a l s o extremely important in p r o v i d i n g feeding and l o a f i n g areas. The r e l a t i v e importance of these two h a b i t a t types can best be i n d i c a t e d by c o n s i d e r i n g the f o l l o w i n g p o i n t s : 1. The occurrence of ducks on foreshore areas other than the t i d a l marshes. 2. The behaviour of the ducks on the t i d a l marshes. 3. The e x i s t e n c e of night f l i g h t s between the t i d a l marshes and a g r i c u l t u r a l a r e a s . 4. The occurrence of ducks on a g r i c u l t u r a l a r e a s . 5. The r e l a t i v e q u a n t i t i e s of food consumed on the two ar e a s . The data on the occurrence and food habits of ducks were assembled in an organized manner to meet d e f i n i t e o b j e c t i v e s . As such, they are considered to be v a l i d . Observations of duck behaviour on the t i d a l marshes, f l i g h t s between the t i d a l marshes and a g r i c u l t u r a l a r e a s , and duck occurrence on the a g r i c u l t u r a l a r e a s , were made on an i r r e g u l a r b a s i s . However, s i m i l a r o bservations have a l s o been made by other b i o l o g i s t s working on the Fraser d e l t a . Although they are not su b s t a n t i a t e d by any complete and organized body of d a t a , they are nevertheless considered to be sound. The w i n t e r - l o n g occurrence of approximately f i f t y percent of the ducks on foreshore areas other than the t i d a l marshes i s s i g n i f i c a n t . From November to March, the period during which maximum numbers of ducks occurred on the d e l t a , the p r o p o r t i o n of ducks found on n o n - t i d a l marsh foreshore areas ranged from f o r t y to seventy percent. These percentages do not inc l u d e ducks l o a f i n g on open water o f f - s h o r e from the t i d a l marsh v e g e t a t i o n . The mud f l a t s o f f - s h o r e from the t i d a l marshes, and those mud f l a t s flooded by s a l t water on Brunswick Hunting Ground, Boundary Bay, and Mud Bay, do not support any s i g n i f i c a n t growth of v e g e t a t i o n of known value to puddle ducks. Even the narrow band of s a l t marsh i n Boundary and Mud Bays produces l i t t l e duck food. Marine crustaceans and pelecypods are probably a v a i l a b l e on the mud f l a t s , but these are of more value to d i v i n g ducks. Since the four puddle duck species studied were u s u a l l y found r e s t i n g on open water too deep f o r f e e d i n g , i t i s reasonable to assume that these foreshore areas l a c k i n g t i d a l marsh vege t a t i o n are more important for l o a f i n g than f o r f e e d i n g . Since a larg e p r o p o r t i o n of the duck population was present on foreshore areas where there was very l i t t l e duck food, and s i n c e the t i d a l marshes are known to produce s u i t a b l e duck food, i t seems reasonable to assume that e i t h e r they are not an important feeding a r e a , perhaps because they do not provide adequate feeding c o n d i t i o n s , or e l s e there i s another important feeding area elsewhere. Observations of duck behaviour i n d i c a t e the p r o b a b i l i t y that both these assumptions are c o r r e c t . 82 The behaviour of ducks on the t i d a l marsh appeared to be most s t r o n g l y influenced by t i d a l a c t i o n . Ducks u s u a l l y concentrated in a l i n e c l o s e to the edge of the water, and moved inwards and outwards with the r i s i n g and f a l l i n g t i d e s . They were most f r e q u e n t l y observed l o a f i n g or feeding over shallow water, but those few deposited on unflooded p o r t i o n s of the t i d a l marsh by f a l l i n g t i d e s , i n v a r i a b l y flew out to open water wi t h the approach of darkness. Ducks feeding on the t i d a l marshes were most f r e q u e n t l y observed in September, February, March, and A p r i l , when very low t i d e s occurred during d a y l i g h t hours. Under these circumstances, ducks fed on the unflooded port i o n s of the t i d a l marsh. From October to January, high t i d e s during d a y l i g h t hours r e s t r i c t e d feeding to only a few hours each day. However, even when t i d e l e v e l s were optimum, i t was f r e q u e n t l y observed that l e s s than f i v e percent of the population was f e e d i n g . These observations suggest that during that p o r t i o n of the winter when ducks are most numerous, the t i d a l marshes are used p r i m a r i l y as l o a f i n g areas during the d a y l i g h t hours. The observation that ducks form concentration 1 ines which move in and out wi t h the t i d e was p r e v i o u s l y made by Benson ( 1 964 ) . Notably, he concluded that the t i d a l marshes were used p r i m a r i l y as l o a f i n g a r e a s , w i t h feeding being of secondary importance. He s t r e s s e d the importance of the a g r i c u l t u r a l areas in p r o v i d i n g food f o r w i n t e r i n g ducks. The habit of Fraser d e l t a ducks of making n i g h t l y f l i g h t s to a g r i c u l t u r a l areas f o r feeding purposes, has long been recognized. Munro (1943, 1949a) mentioned t h i s behaviour and noted that night f l i g h t s to 83 the f i e l d s began two or three days a f t e r the onset of the hunting season i n e a r l y October. Ducks on L u l u , Sea, and lona Islands f l y i n t o adjacent f i e l d s a f t e r dark (Benson, 1961). Delta n a t u r a l i s t s report s i m i l a r behaviour by a l l four duck species in f l y i n g i n t o the f i e l d s around Ladner and C l o v e r d a l e , from the t i d a l marshes and from Boundary and Mud Bays. From October, 1966 to February, 1967, i t was observed that only a small percentage of the ducks on the t i d a l marshes flew inland in the f i r s t r e c o gnizable f l i g h t a f t e r dark. S i m i l a r l y , only a small p o r t i o n of the ducks observed during the day on the t i d a l marsh were seen in the e a r l y morning f l i g h t . On the assumption that a large p r o p o r t i o n of the t i d a l marsh ducks are feeding in the f i e l d s during the n i g h t , and s i n c e only a small percentage are seen in the f l i g h t s , i t seems p o s s i b l e that there might be a s e r i e s of inward and outward f l i g h t s o c c u r r i n g throughout the n i g h t . Although the commencement of the night f l i g h t s was mentioned by Munro ( 1 9 ^ 3 ) , who suggested that they were a d i r e c t response to hunting pressure at the beginning of the hunting season, there are no references to the approximate date by which time the night f l i g h t s cease. Observations made on the t i d a l marsh during the period above suggest that well defined night and morning f l i g h t s cease e n t i r e l y about one week a f t e r the c l o s e of the hunting season in e a r l y January. This i s probably f u r t h e r evidence to suggest that hunting pressure i s the cause of these f l i g h t s . In a d d i t i o n to the evidence f o r f i e l d feeding suggested by the night and morning f l i g h t s during the duck hunting season, a number of. d i r e c t observations of daytime f i e l d feeding v/ere made at i r r e g u l a r i n t e r v a l s . The e a r l i e s t observations were of several hundred ducks of a l l 8k four species feeding in dry barley and pea f i e l d s in l a t e September and e a r l y October. With the onset of the hunting season, however, daytime f i e l d feeding ceased. However, by the beginning of November, small f l o c k s , and e v e n t u a l l y f a i r l y l a r g e f l o c k s of Widgeon were seen in flooded pastures and in flooded f i e l d s of w i n t e r rye (Lolium s p ) . It was apparent that some f l o c k s of Widgeon a r r i v e d on the f i e l d s during the n i g h t , and stayed f o r p a r t s of the day. By e a r l y December, the other three species began to appear in the f i e l d s . The number of ducks s l o w l y increased u n t i l the end of the hunting season in e a r l y January, a f t e r which i t seemed to increase s i g n i f i c a n t l y . Ducks then continued to feed in the f i e l d s during d a y l i g h t hours u n t i l the end of March. The l a s t point worthy of c o n s i d e r a t i o n , in attempting to determine the r e l a t i v e importance to ducks of the two types of h a b i t a t , i s the q u a n t i t i e s of food analysed from ducks c o l l e c t e d on each h a b i t a t type. It was noted p r e v i o u s l y that the small sample s i z e and small volumes analysed d i d not permit v a l i d conclusions to be drawn regarding t h i s q u e s t i o n . However, the data do suggest the p o s s i b i l i t y of a seasonal change in the r e l a t i v e importance of the two feeding areas. The l a r g e s t volumes of food recovered from i n d i v i d u a l ducks were obtained from t i d a l marshes in September and e a r l y October, from a g r i c u l t u r a l areas from l a t e October to January, and from t i d a l marshes from February to A p r i l . In s y n t h e s i z i n g the information a v a i l a b l e on Fraser d e l t a ducks, It seems probable that the t i d a l marshes and a g r i c u l t u r a l areas have a d i f f e r e n t r e l a t i v e importance to the ducks at d i f f e r e n t times of the year. The probable sequence of events is as f o l l o w s : 1. In September, the duck population i s f a i r l y s m a l l , and most ducks are on the t i d a l marsh area; food a v a i l a b i l i t y on the t i d a l marshes i s at i t s peak because plants are j u s t r e l e a s i n g t h e i r seeds, and the vegetation i s unflooded during much of the day; duck feeding on the t i d a l marsh is e x t e n s i v e ; a g r i c u l t u r a l areas are r e l a t i v e l y dry; f i e l d feeding during day or night i s not e x t e n s i v e . 2. By e a r l y October, the duck population is i n c r e a s i n g , and a p r o g r e s s i v e l y l a r g e r proportion are l o a f i n g on non-tidal marsh po r t i o n s of the foreshore; daytime t i d e s are changing so that the t i d a l marshes are flooded f o r i n c r e a s i n g l y longer periods during the day; food a v a i l a b i l i t y on the t i d a l marshes during d a y l i g h t hours is g r e a t l y reduced because of the t i d a l f l o o d i n g ; t i d a l marsh feeding i s g r e a t l y reduced, even at optimum t i d e l e v e l s ; the duck hunting season is underway, with hunters often f o r c i n g ducks out of f i e l d s and out onto open water; the rainy season has begun and the a g r i c u l t u r a l areas are becoming flooded and more a t t r a c t i v e to ducks; daytime f i e l d feeding ceases; morning and night f l i g h t s between the foreshore and a g r i c u l t u r a l areas b e g i n , in c onjunction with extensive night-time feeding in the f i e l d s . 3. - From l a t e October to e a r l y January, the migrating duck population increases g r e a t l y , and then drops to the w i n t e r i n g population l e v e l ; the m a j o r i t y of these ducks loaf 86 on open water over s a l i n e mud and sand f l a t s , or o f f - s h o r e from the t i d a l marshes; food a v a ? l a b i 1 i t y on the t i d a l marsh remains low as daytime t i d e s become higher f o r longer p e r i o d s ; l i m i t e d feeding behaviour on the t i d a l marsh remains r e s t r i c t e d to periods of optimum t i d e l e v e l s ; duck hunting pressure decreases s t e a d i l y with a minor increase j u s t before the c l o s e of the season in e a r l y January; the a g r i c u l t u r a l areas become i n c r e a s i n g l y f l o o d e d ; daytime f i e l d f e e d i n g , f i r s t by Widgeon and then by the other three s p e c i e s , slowly increases from e a r l y November; morning and night f l i g h t s between the foreshore and a g r i c u l t u r a l areas continue. 4. From mid January to March, the migrating duck population f l u c t u a t e s , f i r s t becoming i n c r e a s e d , and then becoming g r a d u a l l y s m a l l e r ; an i n c r e a s i n g proportion of these ducks begin to appear on the t i d a l marshes; food a v a i l a b i l i t y on the t i d a l marsh i s s l o w l y increased as the daytime t i d e l e v e l s decrease; feeding a c t i v i t y on the t i d a l marsh slow l y i n c r e a s e s ; the duck hunting season is c l o s e d ; a g r i c u l t u r a l areas s l o w l y become dry as the r a i n s decrease; f i e l d feeding and l o a f i n g s l o w l y decrease, w e l l - d e f i n e d morning and night f l i g h t s and probably the night-time f i e l d feeding cease s h o r t l y a f t e r the hunting season c l o s e s . 5. By A p r i l , the l a s t stages of the s p r i n g migration are underway and most ducks are present on the t i d a l marsh areas; a v a i l a b i l i t y of food is probably high with low t i d e s o c c u r r i n g 87 during the day; feeding on the t i d a l marsh i s common; the a g r i c u l t u r a l areas are nearly dry; very few ducks are seen in the f i e l d s ; there i s no evidence of morning and night f l i g h t s , or night-time f i e l d f e e d i n g . From the f o r e g o i n g , i t appears that both the t i d a l marshes and the a g r i c u l t u r a l areas are of c o n s i d e r a b l e importance to ducks. But i t i s impossible to say which area i s of greater importance, because the two areas are used more or less i n t e n s i v e l y at d i f f e r e n t times of y e a r , and f o r p a r t i a l l y d i f f e r e n t reasons. The t i d a l marshes appear to provide l o a f i n g h a b i t a t from September u n t i l May, and food p r i m a r i l y in September, e a r l y October, and from February u n t i l May. The a g r i c u l t u r a l areas appear to provide food from e a r l y October to March, and l o a f i n g h a b i t a t from e a r l y January u n t i l February or March. On the basis of the information presented, i t i s d i f f i c u l t to say how c r i t i c a l the t i d a l marshes are in maintaining duck popu-lations on the Fraser d e l t a . Their f u n c t i o n of p r o v i d i n g l o a f i n g areas and duck food during the e a r l y f a l l and l a t e s p r i n g migration periods i s recognized. However, during the peak of the f a l l m i g r a t i o n , from October to January, t h e i r most important f u n c t i o n seems to be the p r o v i s i o n of l o a f i n g a r e a s . If a g r i c u l t u r a l areas continue to provide food, and a l t e r n a t i v e foreshore l o a f i n g areas continue to e x i s t , i t i s p o s s i b l e that a reduction in the area of the present t i d a l marshes might not have a s e r i o u s e f f e c t on the duck population present from October to January. But i t is l i k e l y that any loss of t i d a l marsh h a b i t a t would d e t r i m e n t a l l y a f f e c t the e a r l y f a l l and l a t e s p r i n g migrants. 88 IV. IMPROVEMENTS ON THE TIDAL MARSHES It has been demonstrated that ducks use the t i d a l marshes as l o a f i n g areas and as sources of food. It i s reasonable, t h e r e f o r e , to consider these two uses when planning improvements of the t i d a l marshes. Ducks can be observed l o a f i n g on a l l areas of the t i d a l marshes, although they do appear most commonly over flooded v e g e t a t i o n or out on the open water beyond. They do not normally go i n t o standing vegetation 1i ke Sc? rpus val idus or Typha 1 at i f o l i a , unl ess i t i s unusua11 y wi ndy. And even under windy c o n d i t i o n s , they may o f t e n stay out on open water. They appear to pr e f e r f l a t open areas w i t h good v i s i b i l i t y f o r l o a f i n g , whether these be on dry or submerged marsh. This type of topography i s c h a r a c t e r i s t i c of the t i d a l marshes and adjacent mud f l a t s , so there seems l i t t l e reason to attempt to improve on them by in c r e a s i n g the area of l o a f i n g h a b i t a t . The information on food a v a i l a b i l i t y and duck food habits on the t i d a l marshes suggests two p o s s i b l e improvements. F i r s t , s i n c e the most abundant plant species produce seeds on only the higher l e v e l s of the marsh, water le v e l c o n t r o l by d i k i n g and p o s s i b l y pumping, could be used to increase seed production on the lower l e v e l s of the marsh. Water l e v e l c o n t r o l would a l s o increase the a v a i l a b i l i t y of seeds a f t e r they had been produced, s i n c e there would be constant water l e v e l s to permit feeding on a twenty-four hour b a s i s . Poor feeding c o n d i t i o n s due to winte r daytime f l o o d i n g would be e l i m i n a t e d . Second, i f the water l e v e l s on the t i d a l marshes were brought under c o n t r o l , arid the growth of the pl a n t s could be improved, other s p e c i e s , p o s s i b l y more p a l a t a b l e or productive than the n a t i v e s p e c i e s , could be introduced. Improvements on the a v a i l a b i l i t y of f o o d , as suggested here, could have some very important secondary b e n e f i t s . It was stated in the i n t r o d u c t i o n that some of the a g r i c u l t u r a l areas are being l o s t to r e s i d e n t i a l and i n d u s t r i a l development. There i s every reason to b e l i e v e that t h i s trend w i l l continue and that t h i s w i l l r e s u l t in a d i r e c t l o s s of present duck food producing areas. As t h i s loss o c c u r s , the importance of the t i d a l marshes in p r o v i d i n g duck food w i l l i n c r e a s e . If the production and a v a i l a b i l i t y of food on the t i d a l marshes i s not, then, improved, i t i s probable that reductions w i l l occur in the s i z e of the duck population w i n t e r i n g on the Fraser d e l t a . With the development of industry and a d d i t i o n a l shipping f a c i l i t i e s , the threat of water p o l l u t i o n w i l l i n c r e a s e . The same dikes used to c o n t r o l water l e v e l s w i l l provide some p r o t e c t i o n from v a r i o u s water p o l l u t a n t s , i n c l u d i n g o i l . 1 CHAPTER V l l 1 CONCLUSIONS 1. Ducks are present on the Fraser d e l t a in large numbers from September u n t i l May, w i t h maximum numbers o c c u r r i n g during the peaks of f a l l and s p r i n g m i g r a t i o n s , from October u n t i l December, and from February u n t i l A p r i l . 2. More ducks are seen on the Fraser d e l t a during the f a l l m i g r a t i o n , p a r t i c u l a r l y during November, than during the spring m i g r a t i o n . 3. The s i z e and species composition of the duck population observed on the Fraser d e l t a v a r i e s a n n u a l l y . k. The t i d a l marshes a t t r a c t approximately one-half of the t o t a l of ducks observed on the d e l t a i n w i n t e r , with the l a r g e s t proportions o c c u r r i n g on the t i d a l marshes in September, e a r l y October, l a t e March, A p r i l , and May. 5. The four census u n i t s of the t i d a l marsh a t t r a c t s i m i l a r w i n t e r t o t a l s of ducks, although the r e l a t i v e numbers at each u n i t may vary throughout the w i n t e r . 6. The t i d a l marshes cover approximately 3,733 a c r e s , of which the f i v e g e o g r a p h i c a l l y d i s t i n c t u n i t s c o n t r i b u t e the f o l l o w i n g percentages: Lulu I s l a n d , kO percent; R e i f e l I s l a n d , 20 percent; Westham I s l a n d , 20 percent; Brunswick Hunting Ground, 10 percent; and lona and Sea I s l a n d s , 10 percent. 7. The average width of the t i d a l marshes i s j u s t over one-half m i l e , s l o p i n g from the t h i r t e e n to twelve f o o t t i d e l e v e l at the base of the d i k e s , to the seven foot t i d e l e v e l at the edge of the v e g e t a t i o n . 8. An abrupt decrease in e l e v a t i o n of s i x to eighteen inches u s u a l l y occurs near the ten foot t i d e l e v e l , d i v i d i n g the marsh i n t o an upper and lower zone, each w i t h a d i f f e r e n t v e g e t a t i v e composition. 9. Five Cyperaceae s p e c i e s , Scirpus americanus, Carex Lyngbyei, Eleochar 1s macrostachya , Sci rpus pa 1udosus , and Sci rpus v a l i d u s , t o t a l approximately 93 percent of the t i d a l marsh p l a n t s , with the f i r s t two s p e c i e s , dominant on the lower and upper zone, r e s p e c t i v e l y , t o t a l l i n g 70 percent of the p l a n t s . 10. An a d d i t i o n a l nine species from v a r i o u s p l a n t f a m i l i e s increase the t o t a l to fourteen species growing on the t i d a l marshes. 11. Local d i s t r i b u t i o n of the plant species appears to be determined, at l e a s t i n p a r t , by the degree of t i d a l f l o o d i n g and the degree of drainage from the s i t e . 12. P l a n t d i s t r i b u t i o n over the e n t i r e t i d a l marsh may be influenced by d i f f e r e n c e s in s o i l and water s a l i n i t y . 13. Seed production by the most abundant t i d a l marsh pla n t species appears to be influenced by the degree of t i d a l f l o o d i n g of the f l o r a l p a r t s . 14. The upper zone of the t i d a l marsh i s the most productive a r e a , and seed production on the lower zone v a r i e s widely from year to year, with p l a n t s on the lowest l e v e l s very seldom producing seeds. 15. Estimated long term seed production i n d i c e s suggest that Sci rpus  v a l i d u s and Carex Lyngbyei are almost e q u a l l y the most productive t i d a l marsh s p e c i e s , with Scirpus americanus producing o n e - f i f t h - ' 92 t h e i r q u a n t i t y and Scirpus paludosus and E l e o c h a r i s macrostachya producing approximately one-twentieth t h e i r q u a n t i t y . 16. The t i d a l marsh food items of g r e a t e s t importance to the four duck species are seeds from Carex Lyngbyei , Sc i rpus va1i dus , and Sc i rpus  americanus. 17. The most important food items obtained from a g r i c u l t u r a l areas by a l l four duck species are the seeds from Polygonum 1 apathi f o l j urn and Polygonum p e r s i c a r i a . 18. M a l l a r d , P i n t a i l , and Green-winged Teal consume mostly seeds, w h i l e Widgeon consume mostly green v e g e t a t i o n , of which winter rye (Lolium sp.) and several u n i d e n t i f i e d grass species are important. 19. From l a t e October u n t i l e a r l y January, the t i d a l marshes appear to be most important as l o a f i n g a r e a s , w h i l e - d u r i n g the remaining two p o r t i o n s of the September u n t i l May period they are important f o r both l o a f i n g and f e e d i n g . 20. From l a t e October u n t i l e a r l y January, the r e l a t i v e importance of the t i d a l marshes in p r o v i d i n g duck food appears to be minor, and i t appears that during t h i s p e r i o d , the adjacent a g r i c u l t u r a l areas provide the major proportion of the duck food. 21. P r o v i d i n g that a l t e r n a t e foreshore l o a f i n g areas remain a v a i l a b l e , and that a g r i c u l t u r a l areas continue to provide food, i t i s u n l i k e l y that minor losses to the t i d a l marsh h a b i t a t w i l l r e s u l t in great reductions in the migrating and w i n t e r i n g duck p o p u l a t i o n s . 22. The c o n t r o l of water l e v e l s , by d i k i n g and pumping, in order to increase food production and a v a i l a b i l i t y , and a l s o to protect the area from the *. 93 e f f e c t s of water p o l l u t i o n , would l i k e l y improve the a b i l i t y of t i d a l marshes to support migrating and w i n t e r i n g duck p o p u l a t i o n s . BlBLIOGRAPHY 95 Armstrong, J . E. 1956. S u r f i c i a l Geology of Vancouver Area, B r i t i s h Columbia. Canada Department of Mines and Technical Surveys, Geological Survey of Canada, Paper 55 - 40. Benson, W. A. 1961. An Inventory of Recreation of the P a c i f i c Coast With Special Emphasis. on Waterfowl. Unpublished Report, Canadian W i l d l i f e S e r v i c e , Vancouver, B.C. . 1964. A Waterfowl Management Proposal and a Multi-Purpose Recreational Proposal f o r the Lower Fraser V a l l e y in B r i t i s h Columbia. Unpublished Report, Canadian W i l d l i f e S e r v i c e , Vancouver, B.C. Canada Department of Tran s p o r t , Mete o r o l o g i c a l Branch. 1965 Annual Meteorological Summary With Comparative Data, Vancouver A i r p o r t , 1937 -1965, Vancouver C i t y , 1900 - I965. . I966 Annual Meteorological Summary With Comparative Data, Vancouver A i r p o r t , 1937 - 1966, Vancouver City,.19 0 0 - 1966. . . 1967 Annual Meteorological Summary V/ith Comparative Data, Vancouver A i r p o r t , 1937 - 1967, Vancouver C i t y , 1900 - 1967. Canadian Hydrographic S e r v i c e , Marine Sciences Branch, Department of Mines and Technical Surveys, Ottawa. 1965 Tide and Current T a b l e s , S t r a i t of Georgia to Queen C h a r l o t t e S t r a i t , B r i t i s h Columbia. " . 1966 Tide and Current T a b l e s , S t r a i t of Georgia to Queen C h a r l o t t e S t r a i t , B r i t i s h Columbia. . 1967 Canadian Tide and Current T a b l e s , Juan de Fuca and Georgia S t r a i t s . C o t t l e , W. H. 1949. A Study Of The Feeding Behaviour of the Anatidae Wintering In the Lower Fraser V a l l e y of B r i t i s h Columbia. B. A. T h e s i s . The U n i v e r s i t y of B r i t i s h Columbia. F e r n a l d , M e r r i t t L. 1950. Gray's Manual of Botany, 8th Ed., American Book Company. Harry, Kenneth F. and John B. Wright. 1967. The Climate of Vancouver. Department of Tran s p o r t , Meteorological Branch. Reprint of C i r c u l a r 2985, TEC-258. Hochbaum, H. A. 1955. The Travels and T r a d i t i o n s of Waterfowl. U n i v e r s i t y of Minnesota P r e s s , M i n n e a p o l i s . J e f f r e y , Robert G. 1948. Waterfowl Food Resources of Skagit and Port Susan Bays. In Annual Report, Washington State Department of Game, Olympia, Washington. Kendrew, W. G. and D. Kerr. 1955. The Climate of B r i t i s h Columbia And The Yukon T e r r i t o r y . Queen's P r i n t e r , Ottawa. 96 Lemieux, L o u i s . 1959. Natural H i s t o r y and Management of the Greater Snow Goose, Chen hyperborea a t l a n t i c a . Ph.D. T h e s i s , Laval U n i v e r s i t y , Quebec. Ma l y s h e f f , Andrew. 1951 . Lead Poisoning of Ducks in The Lower Fraser V a l l e y of B r i t i s h Columbia: a Chemical Study. MSc. T h e s i s . The U n i v e r s i t y of B r i t i s h Columbia. M a r t i n , A. C. I960. Food-Habits Procedures, Revised by Leroy J . Korschgen, I963. In W?Id!?fe I nves t i g a t ional Techniques second e d i t i o n , edited by Henry S. Mosby. __ , R. H. Gensch and C. P. Brown. 1946. A l t e r n a t i v e Methods in Upland Game B i r d Food A n a l y s i s . J . W i l d l . Mgmt. 10 ( l ) : 8 - 12. Mathews, W. H. Head, Department of Geology, The U n i v e r s i t y of B r i t i s h Columbia, Vancouver, B. C. Munro, J . A. 1936. Food of the Common Mal l a r d in the Lower Fraser V a l l e y , B r i t i s h Columbia. Condor 38 ( 3 ) : 109 -. 111. •.. 1943. Studies of Waterfowl in B r i t i s h Columbia - M a l l a r d . Can. J . Res. D21: 223 - 260. -_. 1944. Studies of Waterfowl in B r i t i s h Columbia - P i n t a i l . Can. J . Res. D22: 60 - 86. .. 1949a . Studies of Waterfowl in B r i t i s h Columbia - Green-winged T e a l . Can. J . Res. D27 ( 3 ) : 149 - 178. . 1949b. Studies of Waterfowl in B r i t i s h Columbia - Baldpate. Can. J . Res. D27 (5): 289 - 307. P a c i f i c Oceanography Group, J o i n t Committee on Oceanography, Nanaimo, B. C. 1951. Data Record, Fraser River Estuary P r o j e c t , 1950. Sprout, P. N., and W. D. H o l l a n d . 1959- S o i l Survey of Delta M u n i c i p a l i t y , P r e l i m i n a r y Report No. 2 of the Lower Fraser V a l l e y S o i l Survey. B r i t i s h Columbia Department of A g r i c u l t u r e , Kelowna, B. C. Tener, John S. 1948. An I n v e s t i g a t i o n of Some of the Members of the Sub-Family Anatinae i n the Lower Fraser V a l l e y of B r i t i s h Columbia. B. A. T h e s i s , The U n i v e r s i t y of B r i t i s h Columbia. Unger, Irwin A. I 9 6 6 . S a l t Tolerance of Plants Growing in S a l i n e Areas of Kansas and Oklahoma. Ecology 47 0 ) : 154 - 155. United States Department of the I n t e r i o r , Fish and W i l d l i f e S e r v i c e , Bureau of Sports F i s h e r i e s and W i l d l i f e , P o r t l a n d , Oregon. 1967- P a c i f i c Flyway Winter Waterfowl Survey. APPENDIX T A K E N F R O M H A R R V A N D W R I G H T (196V) T A K E N F R O M H A R R V A N D W R I G H T ( 1 9 6 7 ) TOO APPENDIX 3 THE ALKALINITY, CONDUCTIVITY, AND SALINITY OF THE UPPER AND LOWER SOIL HORIZONS OF THE GEORGE C. REIFEL WATERFOWL REFUGE C o n d u c t i v i t y Parts per Sample pH (Millimhos per M i l l i o n Total Number Centimeter) Dissolved S a l t s Upper Lower Upper Lower Upper Lower Horizon Horizon Horizon Horizon Horizon Horizon 1 7.05 7.20 0.4 0 .9 225 500 2 7.00 7.30 . 0 .4 . 0 . 5 225 300 3 7.05 7.10 0.6 0 .9 350 500 4 6.65 6.85 1.1 2.0 625 1,150 5 7.05 6.80 1.2 2.0 650 1,150 6 6.75 6.90 1.0 0.7 550 375 7 7.10 6.80 1.2 1.7 650 925 8 6.95 7.00 0.6 1.7 350 925 9 7.20 7.10 0.6 1.0 350 550 10 7.20 7.10 0.7 0.7 375 375 Mean f o r S o i l Horizon: 7 .00 7.02 0.78 1.21. 435 675 Mean f o r a l l Samples: 7.01 1.0 555 APPENDIX 4 101 COLLECTION DATES, AREAS, AND NUMBERS OF EACH SPECIES SAMPLED FOR FOOD HABITS ANALYSIS Col 1ect ion Area Mai l a r d 1965/ 1966/ 1966 1967 P i n t a i l 1965/ 1966/ 1966 1967 Widgeon 1965/ 1966/ 1966 1967 Green-winged Teal • 1965/ 1966/ 1966 1967 Total Westham I s1 and 39 71 24 23 29 53 29 272 Ladner Marsh 29 12 69 Sea I si and 41 37 25 26 129 Boundary Bay 5 5 Cloverdale 2 2 Yearly T o t a l : 68 121 36 62 37 78 10 65 Grande Total : 189 98 115 75 477 APPENDIX 5 STANDARD VOLUMES OF SEEDS OF THE FOOD SPECIES MOST FREQUENTLY CONSUMED ON THE FRASER DELTA Number Volume Volume of One Spec i es of Seeds = (Ml.) Seed (Ml.) Carex Lyngbyei 21,754 57.50 0.00265 Sci rpus va1idus 36,981 67.90 0.00184 Scirpus americanus 2,855 9.50 0.00333 Scirpus paludosus 11,246 . 43.00 0.00382 Eleocharus macrostachya 2,908 3 .00 0.00103 Si urn sauve 1,000 2.90 0.00290 T r i g l o c h i n maritima 500 0.95 0.00190 Potenti 1 1 a Egedei 904 1.40 0.00155 A l l sma t r iv i a l e - 1,000 2.30 0.00230 Menyanthes t r i f o l i a t a • 316 1.70 0.00538 Ambrosia a r t e m i s i i f o l i a 375 1.20 0.00320 Polygonum p e r s i c a r i a and 1,242 . 2.80 0.00223 Polygonum l a p a t h i f o l i u m Polygonum convolvulus 50 0.20 0.00400 Polygonum a v i c u l a r e 1,640 6.00 0.00366 Echinochloa c r u s g a l l i 2,895 9-50 0.00328 T r i f o l i u r n repens 170 0.10 0.00059 A t r i p l e x patula 400 0.95 0.00238 Plantago major 77 0.13 0.00169 Spergula arvens i s 7,200 10.25 0.00143 Ranunculus repens 73 0.30 0.00411 Rubus procerus and 70 0.20 0.00286 Rubus 1 ac i n i atus L e e r s i a oryzbides 57 0.20 0.00351 Potamogeton pectinatus 151 1 .30 0.00861 Zann i c h e l 1 i a pa 1 l i s t r i s 727 ' 0 .60 0.00083 103 APPENDIX 6 THE NUMBER OF DUCKS OBSERVED DURING AERIAL CENSUSES OF THE FRASER DELTA FORESHORE AND ADJACENT UPLAND AREAS FROM SEPTEMBER, 1965 TO APRIL, 1966 Date Ma l l a r d P i n t a i l Wi dgeon Green-wi nged Teal September 3/65 1,195 795 1,980 3,580 September 17/65 1 ,020 685 2,040 3,070 October 8/65 11 ,550 4,435 8,680 4,435 November 9/65 6,400 1,600 4,800 3,200 November 23/65 10,100 5,780 10,100 2,890 December 9/65 6,350 1,780 16,500 770 February 8/66 3,000 2,160 6,000 840 February 22/66 2,770 1 ,380 5,540 2,490 March 17/66 1 ,600 2,180 6,560 2,330 A p r i l 5/66 4,860 1 ,945 6,800 3,895 Total Number: 48,845 22,650 69,000 27,410 Percent: 29.1 13.5 41.1 16.3 104 APPENDIX 7 THE NUMBER OF DUCKS OBSERVED DURING AERIAL CENSUSES OF THE FRASER DELTA FORESHORE AND ADJACENT UPLAND AREAS FROM SEPTEMBER, 1966 TO MAY, 1967 Date M a l l a r d P i n t a i l Widgeon Green-winged Teal September 22/66 3,260 5,050 11,670 6,685 September 29/66 2,785 2,348 13,220 6,142 October 7/66 3,345 7,232 14,592 7,929 October 13/66 2,618 3,815 5,471 16,890 October 27/66 5,702 9,532 11,623 7,019 November 10/66 13,631 21,555 17,900 10,504 November 24/66 14,134 22,573 10,331 9,646 December 8/66 6,967 11,655 13,251 5,773 December 22/66 13,273 17,791 12,843 10,002 January 15/67 4,434 1,197 3,023 - 1 ,081 January 30/67 6,507 5,632 2,332 1,508 February 9/67 4,063 6,315 7,635 3,291 February 23/67 3,642 7,901 8,242 r ' 2,243 March 9/67 5,499 9,389 12,296 3,288 March 28/67 1,925 1,220 12,083 5,244 A p r i l 11/67 2,867 5,276 11 ,015 6,055 A p r i l 20/67 1,034 2,623 11,597 7,995 May 4/67 324 430 3,708 9,280 May 18/67 151 19 130 77 Total Number: 96,161 141,553 182,962 120,652 Percent: 17.8 26.1 33.8 22.3 APPENDIX 8 105 THE NUMBER OF DUCKS OBSERVED ON THE TIDAL MARSH AND NON-TIDAL MARSH CENSUS UNITS IN TOTAL AND AS A PERCENTAGE OF THE TOTAL DELTA POPULATION FROM SEPTEMBER, 1965 TO APRIL, 1966 Date T i d a l Marsh Census Units Number Percentage Non-Tidal Marsh Census Units Number Percentage September 3/65 7,395 September 17/65 6,595 October 8/65 23,560 November 9/65 6,330 November 23/65 11,390 December 9/65 14 ,015 February 8/66 6,460 February 22/66 8,036 March 17/66 6,009 A p r i l 5/66 12,460 93.0 96.7 81.3 39.8 39.5 55.1 54.0 58.1 41.3 64.1 565 230 5,410 9 ,605 17,480 11,405 5,510 5,809 8,547 6,980 7.0 3.3 18.7 60.2 60.5 44.9 46.0 41.9 58.7 35-9 Total Number: Cumulative Percentage: 102,250 58.8 71,541 41.2 106 APPENDIX 9 THE NUMBER OF DUCKS OBSERVED ON THE TIDAL MARSH AND NON-TIDAL MARSH CENSUS UNITS IN TOTAL AND AS A PERCENTAGE OF THE TOTAL DELTA POPULATION FROM SEPTEMBER, I966 TO MAY, 1967 T i d a l Marsh Non-Tidal Marsh Census Units Census Units Date Number Percentage Number Percentage September 22/66 25,631 96.4 1,040 3.6 September 29/66 22,995 9 3 . 8 1,500 6.2 October 7/66 28,126 85.O 4,972 15.0 October 13/66 26,690 92.8 2,104 7.2 October 27/66 11,692 . 34 .5 22,184 65-5 November 10/66 25,817 40 .6 37,772 . 59.4 November 24/66 23,422 41 .2 33,262 58.8 December 8/66 16,358 43.4 21,288 56.6 December 22/66 21,067 37.9 34,584 62.1 January 15/67 5,335 54.8 4,400 45.2 January 30/67 4,027 25.0 12,031 75.0 February 9/67 5,150 24 .2 16,154 75.8 February 23/67 , 7 , 3 2 6 32.2 15,339 67.8 March 9/67 8,682 28.4 21,921 71 .6 March 22/67 13,289 63.7 7,559 36.3 A p r i l 11/67 20,650 8 0 . 3 5,010 19.7 A p r i l 20/67 17,890 76.1 5,652 23.9 May 4/67 11,271 81.4 2,588 18.6 May 18/67 363 91.5 34 8.5 Total Number: 295,688 249,397 Cumulat ive Percentage: 45.8 APPENDIX 10 THE NUMBER AND PERCENTAGE OF THE TOTAL NUMBER OF DUCKS OBSERVED ON EACH OF THE TIDAL MARSH CENSUS UNITS FROM SEPTEMBER, 1965 TO APRIL, 1966 lona & Sea Islands Lulu Island R e i f e l & Westham Brunswick Hunting Islands Ground Date No. Percentage No. Percentage No. Percentage No. Percentage • Sept. 3 685 9-3 1,945 26.3 385 5.2 4,380 59.2 Sept. 17 805 12.2 3,250 49.2 110 1.7 2,430 36.9 Oct. 8 5,900 25.0 1,950 8.3 9,460 40.2 6,250 26.5 Nov. 9 305 4.8 700 11.0 4,125 65.2 1,200 19.0 Nov. 23 2,600 22.8 3,910 34.3 4,330 38.0 550 4.9 Dec. 9 3,210 22.9 1,825 13-1 5,430 38.7 3,550 25.3 Feb. 8 880 •13-6 1,310 20.3 4,000 61.9 270 4.2 Feb. 22 2,406 29.9 1,870 . 23.3 2,430 30.2 1,330 16.6 Mar. 17 2,049 34.1 730 12.2 2,125 35.3 1,105 . 18.4 Apr. 5 5,990 48.0 3,360 27.0 2,750 22.1 360 2.9 Total Number: 24,830 20,850 35,145 21,425 Cumulat ive Percentage: 24.3 20.4 34.4 20.9 o -^1 APPENDIX 11 THE NUMBER AND PERCENTAGE OF THE TOTAL NUMBER OF DUCKS OBSERVED ON EACH OF THE TIDAL MARSH CENSUS UNITS FROM SEPTEMBER, 1966 TO MAY, 1967 lona S Sea Islands Lulu Island R e i f e l & Westham Brunswick Hunting Islands Ground Date No. Percentage No. Percentage No. Percentage No. Percentage Sept. 22 5,546 21.6 7,980 31.1 3,200 12.6 8,905 34.7 Sept. 29 3,310 14.3 8,000 34.4 1,615 7.0 10,270 44.3 Oct. 7 2,489 8.9 5,550 19.7 4,985 17.7 15,102 53.7 Oct. 13 4,321 17.3 5,742 23.0 1,072 4.3 13,851 55.4 Oct. 22 2,735 23.4 3,869 33.1 3,919 33.5 1,171 10.0 Nov. 10 5,438 21.1 7,228 28.0 5,742 22.2 7,409 28.7 Nov. 24 2,573 10.4 5,087 20.6 8,143 33.0 8,890 36.0 Dec. 8 1,253 1.1 1,227 7.5 11,931 73.0 1,942 11.8 Dec. 22 5,119 24.3 3,682 17.5 9,314 4 4 . 2 2,953 14.0 J a n . 15 2,472 46.4 923 . • 17.3 1,671 31.4 262 4.9 Jan. 30 1,035 25.8 826 20.6 2,075 51.7 . 77 1.9 Feb. 9 2,887 56.1 1,133 22.0 1,083 ' 21.0 46 0.9 Feb. 23 3,384 46.1 1,047 14.3 2,632 35.9 270 3.7 Mar. 9 3,088 31.6 2,052 21 .0 4,497 46.1 128 1.3 Mar. 22 4,648 35.0 3,123 23.5 5,424 40.8 93 0.7 Apr. 11 3,508 17.0 10,042 48.9 6,545 31". 9 454 2,2 Apr. 20 6,714 37.5 5,781 32.3 4,567 25.6 829 4 . 6 May k 4,444 39.5 3,042 27.0 3,159 2 8 . 0 622 5.5 May 18 183 50.4 60 16.5 108 29.8 12 3.3 Tota 1 Number: 64,947 76,394 81,682 73,286 Cumulative Percentage: 21.9 25.8 27.5 .... 24.8 o CO APPENDIX 12 THE NUMBER OF EACH DUCK SPECIES OBSERVED ON THE IONA AND SEA ISLAND TIDAL MARSH FROM SEPTEMBER, 1966 TO MAY, I967 Date M a l l a r d P i n t a i l Widgeon Green-winged Teal Sept. 22/66 946 400 2,100 2,100 Sept. 29/66 700 50 200 2,160 Oct. 7/66 707 130 1,352 300 Oct. 13/66 1 ,360 202 1,517 1 ,242 Oct. 27/66 1,017 1,033 0 685 Nov. 10/66 714 61 3,140 1,523 Nov. 24/66 545 235 1,521 272 Dec. 8/66 290 147 810 6 Dec. 22/66 1,359 250 3,360 150 J a n . 15/67 538 48 1,339 547 J a n . 30/67 557 109 106 209 Feb. 9/67 351 145 1,870 521 Feb. 23/67 417 233 2,001 733 Mar. 9/67 184 282 2,405 - 217 Mar. 22/67 147 291 2,595 1,615 Apr. 11767 493 219 1,862 934 Apr. 20/67 83 57 1,989 4,585 May 4/67 74 24 728 3,618 May 18/67 53 0 . 85 45 Total Number: 10,535 3,916 29,034 21,462 Cumulat ive Percentage: 16.2 6.0 44.7 33.1 n o APPENDIX 13 ; THE NUMBER OF EACH DUCK SPECIES OBSERVED ON THE LULU ISLAND TIDAL MARSH FROM SEPTEMBER, 1966, TO MAY, 1967 Date M a l l a r d P i n t a i l Widgeon Green=winged T e a l S e p t . 22/66 500 500 5,980 1 ,000 S e p t . 29/66 500 200 -7,100 200 O c t . 7/66 100 250 5,000 200 O c t . 13/66 397 599 86 4,660 O c t . 27/66 268 386 2,904 311 Nov. 19/66 411 1,376 4,779 662 Nov. 24/66 349 1,033 720 2,985 Dec. 8/66 130 . 298 94 705 Dec. 22/66 626 1,149 374 1,533 J a n . J 5 / 6 7 387 104 425 7 J a n . 30/67 207 230 157 232 Feb. 9767 226 123 387 397 Feb. 23/67 132 153 725 37 Mar. 9/67 1 301 1,515 235 Mar. 28/67 121 227 1,964 -811 A p r . 11/67 210 3 ,010 3,612 3,210 A p r . 20/67 68 296 4,444 973 May 4/67 68 32 907. . 2,035 May 18/67 21. 10 6 23 T o t a l Number: 4,722 . 10,277 41 ,179 20,216 Cumulat i v e P e r c e n t a g e : 6.1 13.5 53.9 26.5 I l l APPENDIX 14 THE NUMBER OF EACH DUCK SPECIES OBSERVED ON THE REIFEL AND WESTHAM ISLANDS TlDAL MARSH FROM SEPTEMBER, 1966 TO MAY, 1967 Date M a l l a r d P i n t a i l Widgeon Green-winged Teal Sept. 22/66 800 1,500 250 650 Sept. 29/66 400 1,115 50 50 Oct. 7/66 1 ,137 3,564 158 126 Oct. 13/66 279 688 87 18 Oct. 27/66 1 ,068 317 1 ,210 1,324 Nov. 10/66 3,184 1,027 830 701 Nov. 24/66 4,713 647 2,040 743 Dec. 8/66 2,543 1,694 4,899 2,795 Dec. 22/66 3,314 1,498 1,436 3,066 J a n . 15/67 1,014 170 215 272 Jan. 30/67 1,218 46 277 534 Feb. 9/67 739 2 . 209 133 Feb. 23/67 934 57 1,117 524 Mar. 9/67 917 869 1,575 1,136 Mar. 28/67 898 115 2,751 1,660 Apr. 11/67 1,038 1,257 3,698 552 Apr. 20/67 310 375 2,691 1,191 May 4/67 42 24 1,506 1,587 May 18/67 64 8 32 4 Total Number: 24,612 14,973 25,031 17,066 Cumulat ive Percentage: 30.1 18.3 30.7 20.9 APPENDIX 15 112 THE NUMBER OF EACH DUCK SPECIES OBSERVED ON THE BRUNSWICK HUNTING GROUND TIDAL MARSH FROM SEPTEMBER, 1966 to MAY, I967 Date M a l l a r d P i n t a i l Widgeon Green=winged Teal Sept. 22/66 910 2,150 3,300 2,545 Sept. 29/66 1 ,000 0 5,770 3,500 Oct.7/66 758 57 8,030 6,257 Oct. 13/66 300 901 3,000 9,650 Oct. 27/66 293 456 422 0 Nov. 10/66 1,571 1,614 1,638 2,586 Nov. 24/66 990 2,493 4,120 1,287 Dec. 8/66 732 460 750 0 Dec. 22/66 157 526 1 ,765 505 J a n . 15/67 123 89 50 0 Jan. 30/67 Ik 0 3 0 Feb. 9/67 14 2 30 0 Feb. 23/67 10 77 131 52 Mar. 9/67 7 3 97 21 Mar. 28/67 7 11 61 14 Apr. 11/67 31 55 368 0 Apr. 20/67 8 480 341 0 May 4/67 6 49 299 268 May 18/67 12 0 . 0 0 Total Number: 7,003 9,423 30,175 26,685 Cumulative Percentage: 9.5 12.9 41 . 2 36.4 APPENDIX 16 113 THE TOTAL NUMBER OF EACH DUCK SPECIES OBSERVED ON ALL FOUR TIDAL MARSH CENSUS UN ITS COMB I NED, FROM SEPTEMBER, 1966 TO MAY, 1967 Date M a l l a r d P i n t a i l Widgeon Green-winged Teal Sept. 22/66 3J56 4,550 11,630 6,295 Sept. 29/66 2,600 1,365 13,120 5,910 Oct. 7/66 3,702 4,100 14,450 6,883 Oct. 13/66 2,332 2,390 4,690 15,578 Oct. 27/66 2,646 2,192 . 4,536 2,320 Nov. 10/66 5,880 4,078 10,387 5,472 Nov. 24/66 6,597 4,408 7,130 5,287 Dec. 8/66 3,695 2,599 6,557 3,506 Dec. 22/66 5,456 3,423 6,935 5,254 Jan. 15/67 2,069 411 2,029 826 Jan. 30/67 2,056 385 597 975 Feb. 9/67 1,330 272 2,496 1,051 Feb. 23/67 1,483 520 . • 3,974 1,346 Mar. 9/67 1,109 1,455 5,592 1,609 Mar. 28/67 1,173 644 7,371 4,100 Apr. 11/67 1,772 4,688 9,540 4,696 Apr. 20/67 469 1,208 9,465 6,749 May 4/67 190 129 3,440 7,508 May 18/67 150 18 123 72 Total Number: 47,865 38,835 124,152 85,437 Cumulative Percentage: 16.2 13.1 41.9 28.8 114 APPENDIX 17 THE INCIDENCE OF LEAD SHOT INGESTION BY ANATINIDS WINTERING ON THE FRASER DELTA DURING 1965 - 1966 AND 1966 - 1967 Species Area Sampled Number Sampled Number Contai n i ng Lead Shot Percent Conta i n i ng Lead Shot Ma 11ard P i n t a i 1 Widgeon Green-wi nged Teal Ladner Marsh Sea Island Westham Island Total : Ladner Marsh Sea Island Westham Island T o t a l : Ladner Marsh Sea Island Westham Island Total : Ladner Marsh Sea Island Westham Island Boundary Bay Clover d a l e Total : 38 41 117 196 14 37 49 100 12 25 86 123 9 26 37 5 2 . 79 8 4 10 22 1 4 5 21.0 9 .8 8.6 11.2% 7.2 8.2 5.0% 4 . 0 1.2 1.6% .0% 115 APPENDIX 18 COMPARATIVE DATA BY SEVERAL AUTHORS' ON THE INGESTION OF LEAD SHOT BY FRASER DELTA ANAT INIDS Author and Date Present Study Munro Tener C o t t l e Maiysheff 1965/66 Spec!es (1936) (1948) (1949) (1951) 1966/67 Mallard 12.2? (90)* 16.1? 10.0? 16 .5? 11.2? (59) (61) (79) (196) P i n t a i l Not 5 . 0 ? 0 . 0 ? 22 .9? 5 .0? Studied (20) (16) (35) (100) Widgeon Not 0? 0 . 0 ? 0 . 0 ? 1.6? Stud i ed (22) (21) (15) (123) Green- Not 0 . 0 ? 3 . 6 ? 0 . 0 ? 0 . 0 ? wi nged Stud i ed (27) (56) (2) < (79) Teal " The number in parentheses i s the sample s i z e . APPENDIX 19 THE COMPOSITION OF FOOD CONSUMED BY MALLARD* Volume Percent Frequency of Percent Importance Importance Species (ml.) Volume Occurrence Frequency Value** Index Carex Lyngbyei .115.94 33.9 108 57.1 1935.69 100.00 Sci rpus v a l i d u s 51.98 15 .2 102 54.0 820.80 42 . 4 Polygonum spp. 61.84 18.1 58 30.7 555.67 28.7 Scirpus americanus 15.59 4.6 96 50.8 233.68 12.1 A l i sma t r i v i a l e 43.07 12.6 14 7.4 93.24 4 . 8 E l e o c h a r i s macrostachya 3.25 1.0 61 32.3 32.30 1.6 Echinochloa c r u s g a l l i 10.17 3.0 13 6.9 20.70 1.1 Ambrosia a r t e m i s i i f o l i a 2.87 0.8 24 12.7 10.16 0.5 Menyanthes t r i f o l i a t a 3.61 1.1 18 9.5 .10.45 0.5 At r i pi ex patu1 a 4.59 1.3 8 4 .2 5.46 0.3 Potamogeton pectinatus 4.27 1.3 8 4 .2 5.46 0.3 Sium sauve 1.50 0.4 15 7.9 3.16 0.2 T r i g loch i n maritima 1.82 0.5 11 5.8 2.90 0 . 2 Z a n n i c h e l l i a p a l u s t r i s 0.90 0.3 7 3 .9 1.11 0. 1 Potent i11 a Egede i 0.43 0.1 15 7.9 0.79 0 L e e r s i a o r yzoides 0.23 0.1 9 4 . 8 0.48 0 U n i d e n t i f i e d v e g e t a t i v e m a terial 19.47 5.7 41 21.7 123.69 6 . 4 -* Based on a pooled sample of 341 .53 ml. obtained from the crops and gi z z a r d s of 189 mallards col 1ected from August to A p r i l , 1965 - 1966 and 1966 - 1967. **lmportance Value = Percent Frequency x Percent Volume. C7\ APPENDIX 20 THE RELATIVE IMPORTANCE OF THE FEEDING AREAS TO THE MALLARD POPULATION, AS SHOWN BY PLANT SPECIES IMPORTANCE VALUES T i d a l Marshes A g r i c u l t u r a l Areas Inland Waters Spec i es Importance Value Species Importance Value Spec i es Importance Value Carex Lyngbyei 1935.69 Polygonum spp. 555.67 Sc i rpus va1idus 820.80 Echinochloa Scirpus americanus 233.68 c r u s g a l 1 i 20.70 A l i sma t r i v i a l e 93.24 Ambrosia Eleochar i s ar t e m i s i i f o l i a 10.16 macrostachya 32.30 A t r i p l e x patula 5.46 Menyanthes Le e r s i a oryzoides 0.48 t r i f o l i ata 10.45 U n i d e n t i f i e d Si urn sauve 3.16 Vegetat ive T r i g l o c h i n maritima 2.90 M a t e r i a l . . . .86.56 P o t e n t i l l a Egedei 0.79 Z a n n i c h e l l i a p a l u s t r i s 1.11 679.03 U n i d e n t i f i e d v e g e t a t i v e m a terial 37.13 3,171.25 Grande T o t a l : 3,855.74 T i d a l Marshes: 8 2 . 3 ? A g r i c u l t u r a l Areas: 17.6? Inland Waters:! 0.1? Potamogeton  pect i natus 5.46 5.46 APPENDIX 21 THE COMPOSITION OF FOOD CONSUMED BY PINTAIL* Volume Percent Frequency of Percent Importance Importance Species (ml.) Volume Occurrence Frequency Value-'* Index Polygonum spp. 49.00 26.4 39 39.8 1050.72 100.0 Carex Lyngbyei 30.95 16.6 49 50.0 830.00 79.0 Sci rpus val idus 35.26 19.0 42 4 2 . 9 815.10 77.6 Scirpus americanus 9.69 5.2 53 54.1 281.32 26.8 Echinochloa c r u s g a l l i 12.07 6.4 8 8.2 52.48 5.0 Scirpus paludosus 8.81 4.7 5 5.1 23.97 2.3 Spergula a r v e n s i s 12.18 6.6 3 3.1 20.46 2.0 Alopecurus g e n i c u l a t u s 6.66 3.6 . 5 5.1 18.36 1.7 A t r i p l e x pa t u l a 2.51 1.4 12 12.2 17.08 1.6 T r i g l o c h i n maritima 2.51 1.4 11 11.2 15.68 1.5 E l e o c h a r i s macrostachya 0.51 0.3 24 24.5 7.35 0.7 Polygonum convolvulus 1.07 0.6 6 6.1 3.66 0.3 Menyanthes t r i f o l i a t a 0.88 0.5 7 - 7.1 3.55 0.3 Polygonum a v i c u l a r e 0.76 0.4 8 8.2 3.28 0.3 Potent i l i a Egedei 0.28 0.2 14 14.3 2.86 0.3 T r i f o l i u m pratense 0.80 0.4 4 4.1 1.64 0.2 Juncus spp. 0.14 0. 1 9 - 9.2 0.92 0.1 Sium sauve 0.24 0. 1 7 7-1 0.71 0.1 U n i d e n t i f i e d v e g e t a t i v e mater i a 1 11.37 6.1 23 23.5 143.35 13.6 -'Based on a pooled sample of 185.69 ml. , obtained from crops and g i z z a r d s of 98 p i n t a i l s c o l l e c t e d from September to March, 1965 -1966 and 1966 - I967. **Importance Value = Percent Frequency x Percent Volume. APPENDIX 22 THE RELATIVE IMPORTANCE OF THE FEEDING AREAS TO THE PINTAIL POPULATION, AS SHOWN BY PLANT SPECIES IMPORTANCE VALUES Ti d a l Marshes A g r i c u l t u r a l Areas Spec ies Importance Val ue Spec i es Importance Value Carex Lyngbyei 830.00 Polygonum spp. 1050.72 Sci rpus v a l i d u s 815.10 Echinochloa c r u s g a l l i 52.48 Scirpus americanus 281.32 Spergula arvensis 29.46 Sci rpus paludosus 23.97 Alopecurus g e n i c u l a t u s 18.36 T r i g l o c h i n maritima 15 .68 A t r i p i ex patula 17.08 E l e o c h a r i s macrostachya 7.35 Polygonum convolvulus 3.66 Menyanthes t r i f o l i a t a 3.55 Polygonum a v i c u l a r e 3 .28 Potent i11a Egedei 2.86 T r i f o l i u m pratense 1.64 Juncus spp. 0.46 Juncus spp. 0.46 Sium sauve 0.71 U n i d e n t i f i e d v e g e t a t i v e m a t e r i a l 100.25-U n i d e n t i f i e d v e g e t a t i v e material . 43.10 1,268.39 2,024.10 Grande Tota1: 3 ,292.49 T i d a l Marshes : .. 61 .5% Agr i c u l t u r a l Areas: 38.5% APPENDIX 2 3 THE COMPOSITION OF FOOD CONSUMED BY WIDGEON* Volume Percent Frequency of Precent Importance Importance Species (ml.) Volume Occurrence Frequency Value5-" Index Lolium sp. v e g e t a t i o n 2 0 5 - 3 7 5 7 . 9 2 7 2 3 . 5 1 3 6 0 . 6 5 1 0 0 . 0 U n i d e n t i f i e d Gramineae vegetat ion 1 0 1 . 2 7 2 8 . 5 34 • 3 0 . 0 8 5 5 . 0 0 6 3 . 0 Carex Lyngbyei 6 . 2 1 1 . 8 2 7 . 2 3 . 5 4 2 . 3 0 3 . 1 T r i f o l i u m v e g e t a t i o n 11 .29 3 . 2 7 6 . 1 1 9 . 5 2 1 . 4 Scirpus americanus 2 . 3 5 0 . 7 23 2 0 . 0 1 4 . 0 0 1 . 0 Sci rpus v a l i d u s 0 . 5 7 0 . 2 31 2 7 . 0 5.40 0 . 4 Polygonum spp. O .83 0 . 2 18 15 . 7 3.14 0 . 2 A g r o s t i s s t o l o n i f e r a 1 . 0 7 0 . 3 7 6 . 1 1 . 8 3 0 . 1 E l e o c h a r i s macrostachya 0 . 2 7 0 . 1 12 1 0 . 4 1.04 0 . 1 A t r i p l e x p a t u l a 0 . 3 9 0 . 1 4 . • 3 . 5 0 . 3 5 0 U n i d e n t i f i e d v e g e t a t i v e m a t e r i a l 2 4 . 9 3 7 . 0 2 8 2 4 . 4 1 7 0 . 8 0 1 2 . 6 Based on a pooled sample of 3 5 4 . 4 4 ml. obtained from the crops and gi z z a r d s of 115 widgeon c o l l e c t e d from October to A p r i l , 1 9 6 5 - 1 9 6 6 and I 9 6 6 - 1 9 6 7 . ** Importance Value = Percent Frequency x Percent Volume. APPENDIX 24 THE RELATIVE IMPORTANCE OF THE FEEDING AREAS TO THE WIDGEON POPULATION, AS SHOWN BY PLANT SPECIES IMPORTANCE VALUES Ti d a l Marshes A g r i c u l t u r a l Areas Species Importance Value Spec ies Importance .Value Carex Lyngbyei 42.30 . Lolium sp. v e g e t a t i o n 1360.65 Scirpus americanus 14.00 U n i d e n t i f i e d v e g e t a t i v e Gramineae 855.00 Scirpus v a l i d u s 5.40 T r i f o l i u m v e g e t a t i o n 19.52 E l e o c h a r i s macrostachya 1.04 Polygonum spp. 3.14 U n i d e n t i f i e d v e g e t a t i v e material 51.24 A g r o s t i s s t o l o n i f e r a 1.83 113.98 A t r i p l e x patula 0.35 U n i d e n t i f i e d v e g e t a t i v e material 119.56 2,360.05 Grande T o t a l : 2,474.03 T i d a l Marshes: 4.6% A g r i c u l t u r a l Areas: 95.4% APPENDIX 25 THE COMPOSITION OF FOOD CONSUMED BY GREEN-WINGED TEAL* Volume Percent Frequency of Percent Importance 1mportance Species (ml.) Volume Occurrence Frequency Value** 1 ndex Polygonum spp. 3.12 20.6 37 49.3 1015.58 100, ,0 Scirpus americanus 1.68 11.1 32 42.7 473.97 46. 7 Sci rpus v a l i d u s 1 .20 8.0 36 . 48.0 384.00 37. ,8 Carex Lyngbyei 1 .28 8.5 27 36 .0 306.00 30. ,1 E l e o c h a r i s macrostachya 0.64 4.2 21 2 8 . 0 117.60 11. ,6 Spergula a r v e n s i s 1.16 7.7 6 8 . 0 61.60 6. , 1 Plantago major 0.79 5.2 5 6.7 34.84 3. .4 Juncus spp. 0.56 3.7 6 8 . 0 29.60 2. .9 Menyanthes t r i f o l i a t a 0.38 2.5 3 4 . 0 10.00 1 , .0 Rubus spp. 0.10 0.7 5 6.7 4.69 0, .5 Ranunculus repens 0.10 0.7 4 5 .3 3.71 0. .4 Polygonum av i c u l a re 0.06 0.4 6 8 . 0 3 .20 0. .3 Tr i f o l i urn repens 0.05 0.3 7 9 .3 2.79 0, .3 Echinochloa c r u s g a l l i 0.07 0.5 4 5.3 2.65 0. .3 T r i g l o c h i n maritima 0.07 0.5 4 5 .3 2.65 0. ,3 T r i f o l i u m sp. 0.06 0.4 3 4 . 0 1.60 0. ,2 Potenti 1 1 a Egedei 0.02 0.1 5 6 .7 0.67 0. , 1 Ambrosia a r t e m i s i i f o l i a 0.01 0.1 4 5 .3 0.53 0. . 1 U n i d e n t i f i e d v e g e t a t i v e materi al 3.75 24.8 14 18.7 463.76 45. .7 * Based on a pooled sample of 15.10 ml. . obtained from the crops and g i z z a r d s of 75 Green-winged Teal c o l l e c t e d from September to March, 1965 - 1966 and 1966 - 1967. ** Importance Value = Percent Frequency x Percent Vo1ume. to to APPENDIX 26 THE RELATIVE IMPORTANCE OF THE FEEDING AREAS TO THE GREEN-WINGED TEAL POPULATION, AS SHOWN BY PLANT SPECIES IMPORTANCE VALUES T i d a l Marshes A g r i c u l t u r a l Areas Importance Importance Species Value Species Value Scirpus americanus 473.97 Polygonum spp. 1015-58 Sci rpus v a l i d u s 384 .00 Spergula a r v e n s i s 61 .60 Carex Lyngbyei 306.00 Plantago major 34.84 E l e o c h a r i s macrostachya 117.60 Juncus spp. 14.80 Juncus spp. 14 .80 Polygonum a v i c u l a r e 3.20 Menyanthes t r i f o l i a t a 10.00 Ranunculus repens 3.71 Tr i g l o c h in mar i t ima 2.65 Tr i f 6 1 i urn repens 2.79 Potenti11 a Egedei 0.67 Echinochloa c r u s g a l l i 2.65 U n i d e n t i f i e d v e g e t a t i v e material _139 -13 Tr i f o l i urn sp. ' 1.60 Ambrosia a r t e m i s i i f o l i a 0.53 1,448.82 Rubus spp. 4.69 U n i d e n t i f i e d v e g e t a t i v e m a t e r i a l 324.63 1,470.62 Grande T o t a l : 2,919-44 T i d a l Marshes: . 49.6? A g r i c u l t u r a l Areas: 50.4? APPENDIX 27 THE TOTAL NUMBER OF DUCKS OBSERVED DURING AERIAL CENSUSES OF THE FRASER DELTA FORESHORE AND ADJACENT UPLAND AREAS CONDUCTED IN EARLY JANUARY* Year Number 1953 27,000 1954 20,000 1955 56,310 1956 50,070 1957 27,150 1958 60,100 1959 5,860 I960 39,800 1961 105,080 1962 74,280 1963 45,345 1965 4,840 1966 11,920 1967 9,735 1968** 57,553 Mean Number: 39,670 * Data f o r 1953 to 1963 from Benson (1964); data f o r 1965 from Canadian W i l d l i f e S e r v i c e . Census conducted December 31, 1967. 

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