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The spring and summer foods of the common mallard (Anas Platyrhynchos platyrhynchos L.) in south Central… Perret, Nolan G. 1962

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THE SIRING AND SUMMER FOODS OF THE COMMON MALLARD (ANAS PLATYRHYNCHOS PLATYRHYNGHOS L. ) IN SOUTH CENTRAL MANITOBA  Nolan G. Perret B.A., University of B r i t i s h Columbia, 1950  A THESIS SUBMITTED IN PARTIAL ItJLFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER  OF  SCIENCE  in the Department of Zoology  We accept t h i s thesis as conforming to the required standard  THE UNIVERSITY' OF BRITISH COLUMBIA APRIL, 1962  In presenting  t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements f o r  an advanced degree at the University of B r i t i s h Columbia, I agree that Library s h a l l make i t f r e e l y available f o r reference  and study.  the  I further  agree that permission for extensive copying of t h i s thesis for scholarly purposes may  be granted by the Head of my Department or by h i s  representatives.  It i s understood that copying or publication of t h i s thesis f o r f i n a n c i a l gain s h a l l not be allowed without my written permission.  Department of Zoology The University of B r i t i s h Columbia, Vancouver 8, Canada. A p r i l 9,  1962  - i -  ABSTRACT  The mallard i s the most important species of North American waterfowl; i t s breeding range has been reduced and i s i n danger of a further reduction due to a g r i c u l t u r a l and drainage p r a c t i c e s .  To maintain mallard populations  at the present l e v e l , i t w i l l be necessary to c o n t r o l and manage s u f f i c i e n t habitat to provide f o r t h e i r needs.  In such a program, the knowledge o f the  food habits of waterfowl i s an e s s e n t i a l t o o l . were:  The objectives o f t h i s study  to determine the spring and summer foods o f the mallard, and to  determine the r e l a t i o n s h i p between u t i l i z a t i o n and a v a i l a b i l i t y of the various foods. A study of the spring and summer food habits of mallards was conducted from 1957 to 1959 on a ICO square mile study area i n south c e n t r a l Manitoba. 211 adult and 135 young mallards were c o l l e c t e d f o r analyses o f stomach contents.  At the same time, ponds were randomly selected from the study area  f o r examination and analyses of faunal and vegetative c h a r a c t e r i s t i c s . In the determination of food habits, the g u l l e t contents proved superior to the gizzard contents.  The animal foods found i n the gizzard were p a r t i a l l y  digested and could not be measured accurately.  There was also the p o s s i b i l i t y  that the hard seeds of aquatic plants p e r s i s t i n the gizzard f o r a long period of time. The spring and summer foods of adult mallards consisted o f 45.7$ plant material and 54*3$ animal material.  The young mallards, on the other hand,  consumed y.Ofo plant and 91.0$ animal foods.  In both adult and young b i r d s the  Class Insecta provided the main source of animal foods, and i n both cases, the majority o f the insect foods were obtained from the orders Trichoptera and  - ii -  Diptera.  In adult mallards the important plant foods were obtained from the  G-ramineae and Chenopodiaceae f a m i l i e s . A d i f f e r e n c e . i n the feeding habits o f adult male and female mallards was found.  The male b i r d s consumed more plant foods and l e s s animal foods than  did the female b i r d s . Pond fauna.increased i n abundance u n t i l a peak was reached i n midsummer then decreased i n numbers.. On the other hand, seeds increased i n abundance i n late summer and decreased the following spring as germination took place.  The  proportion of. plant and animal foods consumed by adult mallards varied with the a v a i l a b i l i t y of these foods; the importance of plant foods i n t h e i r diet decreased during the summer, whereas, the importance of animal foods increased. Considerable variations i n water l e v e l s , from f l o o d to drought conditions, were experienced during the study.  As a.result of the change i n water l e v e l s ,  the amount of emergent vegetation decreased.  The food of young mallards  r e f l e c t e d t h i s change i n habitat; the r a t i o of plant to animal foods consumed decreased from 1957 to 1959. The animal protein intake o f the mallard i s v a r i a b l e and the v a r i a t i o n s i n the consumption of animal and plant foods depend upon their  availability.  The r e l a t i v e proportions'of the various foods eaten may not be o f primary importance; mallards appear to- be able to balance t h e i r diets with widely d i f f e r e n t kinds of food.  - iii -  TABLE OF CONTENTS  Page ABSTRACT .,  . .  i  INTRODUCTION . . . . . . . HISTORICAL REVIEW  1  . . . . .  STUDY AREA . . , General Description Location aeology . . Land Use Upland Cover Water Areas  . . . . . .  • •  METHODS Pond Studies Vegetation Fauna Food Studies . . . . . Sampling S t a t i s t i c s . . . . . , Waterfowl C o l l e c t i o n s  ....  • • • . . . . . • •  3 5 5 5 5 6 6 7  8 8 .....10 10 11 11 12  RESULTS 14 C h a r a c t e r i s t i c s o f Vegetation H Pond C l a s s i f i c a t i o n 15 Factors A f f e c t i n g Plant Communities 17 Seed Production and A v a i l a b i l i t y . 19 C h a r a c t e r i s t i c s of Fauna 20 Differences i n Center and Edge Samples- . . ... . ... 21 Annual Changes . . 23 Seasonal Changes 25 A v a i l a b i l i t y of Bottom Pauna 25 Use of Study Area by Waterfowl 26 Populat ions 26 Breeding pairs 26 Broods 28 Movement o f Waterfowl 30 Adults . . . . . 30 Broods 32 Analysis of Gullet Contents 33 Adult Mallards 33 Plant foods 34 Animal foods 36 Sexual difference i n g u l l e t contents 38 ;  - iv  -  Page 4.0 42 42 45 45 48  Juvenile Mallards Plant foods Animal foods Analysis of Gizzard Contents Adult Mallards Juvenile Mallards DISCUSSION . Feeding Behavior of Mallards Comparison of Gullet and Gizzard Contents Seasonal V a r i a t i o n of Foods Comparison of Foods of Adult and Young Mallards . . . . Food of Adult Mallards Annual Variations Sexual Differences Food of Juvenile Mallards . . . . . Age Differences, . . . . . . . . . . . . Annual Variations Relationship of Food Use to A v a i l a b i l i t y  48 48 50 53 56 57 57 59 60 60 62 64  CONCLUSIONS  65  LITERATURE CITED APPENDIX  68  . . . . . . . . '  1. Bi-weekly changes i n the number of organisms per square foot sample found i n the centers of ponds studied i n 1957, 1958 and 1959 2. Bi-weekly changes i n the number of organisms per square foot sample found i n the edges of ponds studied i n 1957, 1958 and 1959  72 . .  3 . Bi-weekly changes i n the number of organisms per square foot sample found i n the centers and edges of ponds studied i n 1957, 1958 and 1959 . . . . . .  72  73  4 . Occurrence of edge fauna i n the study ponds i n 1957, 1958 and 1959 73 5 . Volume and mean proportion of plant foods found i n the g u l l e t s of 96 adult mallards c o l l e c t e d i n 1957, 1958 and 1959  74  6 . Volume and mean proportion of animal foods found i n the g u l l e t s of 96,adult mallards c o l l e c t e d i n .1957, 1958 and 1959 ,75  -  V  -  Page 7. Volume and mean proportion of plant foods found i n the g u l l e t s of 62. juvenile mallards c o l l e c t e d i n 1957, 1958 and 1959  76  8. Volume and mean proportion of animal foods found i n the g u l l e t s of 62 juvenile mallards c o l l e c t e d i n 1957, 1958 and 1959 . . .  77  9. Plants found i n the gizzards of 211 adult (A) and 135 juvenile (J) mallards c o l l e c t e d i n 1957, 1958 and 1959 .  78  10. Animals found i n the gizzards of 211 adult (A) and 135 juvenile (J) mallards c o l l e c t e d i n 1957, 1958 and 1959  81  11. Mean proportion of plant and animal foods consumed by adult and young mallards during the summers of 1957, 1958 and 1959  82  LIST OF TABLES 1. Ponds studied i n the Minnedosa study area,' 1956 to  1959  9  2. Mallards c o l l e c t e d on Minnedosa study area, 1957 to .  1959 • •  12  3. Types o f ponds found i n the Minnedosa study area (from Evans, 1951) 4. C l a s s i f i c a t i o n of ponds i n Minnedosa study area  16 . . 17  5. Comparison of the abundance of organisms i n center • and edge samples c o l l e c t e d from ponds i n 1957, 1958 and 1959 21 6. Summary o f bottom fauna c o l l e c t i o n s from 161 ponds • i n 1957, 1958 and 1959 • .22 7. Students' " t values of bottom fauna abundance i n • ponds i n 1957-1958, 1957-1959 and 1958-1959 . . . . 23 n  8. Bottom fauna c o l l e c t e d from centers-and edges of ponds i n 1957, 1958 and 1959  24  9. Summary of a e r i a l survey data f o r pothole habitat (Stratum A) i n Manitoba- . . . . . . ;  27  - vi -  Page 10. Summary of ground survey data f o r 1§ square mile Roseneath study area 11. Summary of waterfowl brood surveys i n Manitoba . 1954 to 1959  28  . 29  12. Volume and mean proportion of.foods,found i n the . g u l l e t s of 96 adult mallards collected i n the summer , months of 1957, 1958 and 1959 . 34 13. Plant foods fo.und i n the g u l l e t s of adult mallards ., collected i n 1957 and 1959 36 14. Animal foods found i n the g u l l e t s o f adult mallards c o l l e c t e d i n 1957, 1958 and 1959 .37 15. Per cent composition of the animal foods found i n adult mallards i n 1957 and I959 16. Proportion and per cent composition of major foods found i n the gullets of 50 male and 46 female mallards c o l l e c t e d i n 1957, 1958 and 1959 17.  39  Young mallards c o l l e c t e d for, food habits studies , during the summer months o f 1957, 1958 and 1959 . . 40  18. Volume, and mean .proportion of ..foods .found i n the . g u l l e t s of 62 juvenile mallards c o l l e c t e d i n 1957, . 1958 and 1959 , 19.  . 38  Students' " t " values of plant and animal foods consumed by juvenile mallards i n I 9 5 7 - I 9 5 8 , 1957-1959 and 1958-1959  41  42  2 0 . Proportion of plant foods found i n the g u l l e t s of 62 young mallards.in 1957,. 1958 and .1959 • . ' . • • . 4 3 2 1 . Proportion o f animal foods found i n the g u l l e t s of 62 young mallards i n 1957,. 1958 and 1959 . . . . . . .  44  2 2 . Occurrence of foods found i n the gizzards of 211 adult mallards c o l l e c t e d during the summers of 1957, 1958 and 1959 .  46  2 3 . Occurrence of foods found i n the gizzards of 135 juvenile mallards c o l l e c t e d i n 1 9 5 7 , 1958 and 1959 . 47  - vii -  Page 24. Major plant and animal foods found i n the g u l l e t s and gizzards of 96 adult and 62 young, mallards c o l l e c t e d i n 1957, 1958 and 1959  52  25. Edge fauna c o l l e c t e d from ponds during the period May 1 to June 15 i n 1957, 1958 and 1959  57  26. Proportion o f animal foods consumed by young mallards i n 1957, 1958 and 1959 . ,. .. ... ,. . . . . . . . 61 27. Edge fauna c o l l e c t e d from ponds during the period June .16 to August 15 i n 195.7, 1958 and 1959 . . .. .. 63 Following LIST OF PLATES  , , .  Page  I . Location of Minnedosa study area  5  I I . May 1954« Three i l ponds a period of normal water l e v e cl as t. t a The upper during i s a semi-permanent pond and the lower two are permanent ponds. The pond i n the lower r i g h t i s a flooded dugout . 18 III.  July 1955. During the f i r s t year o f flood conditions the three ponds joined and the c a t t a i l association showed signs of dying out  18  IV. May 1958. After three years o f high water l e v e l s the c a t t a i l association completely disappeared leaving a whitetop-sedge association along the shore .  19  V. July 1959. By midsummer of.the f i r s t , year of. drought conditions the upper pond was dry and the two lower ponds were surrounded by large areas of bare mud .  .  VI. May i960. With the return of normal water conditions the three water areas assumed separate, i d e n t i t i e s as whitetop-sedge ponds VII.  Family Limnephilidae showing the variety of materials used i n the construction of. l a r v a l cases, (magnification X2.2)  19  19  50  LIST OF FIGURES 1. Biweekly changes i n the number of bottom organisms per square foot, center samples 1957, 1958 & 1959 . 25  - viii -  Following Page 2. Biweekly changes i n the number o f bottom organisms per square foot, edge samples 1957, 1958 & 1959 .  25  3i Biweekly changes i n the number o f bottom organisms per square foot i n the center and edge samples of  1957, 1958 & 1959  1  25  4. Occurrence of edge fauna i n study ponds i n 1957,  1958 & 1959  26  5. Proportion of plant and animal foods used by adult < and young mallards, 1957, 1958 and 1959 55 6. Comparison o f p l a i t and animal foods of adult mallards and number of edge fauna per square foot, 1957, 1958 and 1959  57  7. Comparison of plant and animal foods of young mallards and number of edge fauna per square foot, 1957, 1958 and 1959  62  INTRODUCTION  North American waterfowl are a renewable natural resource with economic and r e c r e a t i o n a l values of f a r reaching importance.  Tangible evidence of the  economic importance of the resource was provided by a survey c a r r i e d out by the U.S. Department of the I n t e r i o r (USDI, 1 9 5 6 ) .  The sport of waterfowling  alone was valued highly enough by some two m i l l i o n Americans that they spent 115 m i l l i o n d o l l a r s pursuing the sport i n 1955•  No comparable survey has been  conducted i n Canada, but i t i s safe t o assume that the r e c r e a t i o n a l habits of Canadians are s i m i l a r to those of Americans and that expenditures were also i n the order of several m i l l i o n s of d o l l a r s . The economic and aesthetic values of waterfowl i n r e l a t i o n to other recreations such as photography  and nature study are d i f f i c u l t to assess.  The  aesthetic values are recognized as having an important place i n modern l i v i n g but cannot be compared with those contributing d i r e c t l y to man's s u r v i v a l . Considering a l l i n t e r e s t s , the value of the waterfowl resource i s high and i s important not only to the nation's economy but also to the w e l l being of her people. The mallard (Anas platyrhynchos platyrhynchos L.) i s the most important species of waterfowl i n North America.  The indicated waterfowl breeding  population i n i 9 6 0 was close to 2 0 . 5 m i l l i o n b i r d s , of which the mallard made up 35% (USDI, 1960a). 1959-1960  The mallard also ranks high i n recreation.  During the  hunting season the estimated k i l l of mallards i n the United States  was 2 , 8 5 6 , 0 3 0 or  Utfo  of a l l ducks k i l l e d (USDI, 1 9 6 0 b ) .  The waterfowl population i s an important n a t u r a l resource which i s renewable only i f a s u f f i c i e n t number of b i r d s can f i n d the proper habitat f o r  - 2 -  reproduction.  Mallards have always been widely d i s t r i b u t e d i n the northern  portions of the Northern Hemisphere, however, i n North America the population s i z e and breeding range has diminished i n recent years.  H i s t o r i c a l l y the  American breeding range of the mallard covered most of the continent west of the Hudson Bay, south to Northern V i r g i n i a , Central Missouri, Southern  New  Mexico and Lower C a l i f o r n i a , west to the P a c i f i c coast of the United States and Canada and north to the A r c t i c Coast range i s now  (Bent, 1 9 2 3 ) .  The present breeding  confined mainly to Western Canada and the northern border states  of the c e n t r a l p l a i n s (Mississippi Flyway Council, 1 9 5 8 ) . Despite the loss of habitat and the reduction i n numbers of waterfowl, the popularity of the resource has continued to grow.  In the United States, a  federal l i c e n s e , or duck stamp, i s required by a l l persons engaged i n waterfowl hunting. (Day, 1 9 4 9 ) . (USDI, I 9 5 I ) . (USDI, 1959)  When the f i r s t stamps were issued i n 1934, By 1949, In 1958,  6 3 5 , 0 0 1 were sold  the number of hunters had increased to 1,675,400 1,979,266 stamps were sold to waterfowl  and i n 1959,  1,477,661 were sold (USDI, 1 9 6 0 a ) .  hunters  Thus the main  problems facing waterfowl management today i s a growing demand f o r the resource and a shrinking of breeding habitat which controls the waterfowl supply. The M i s s i s s i p p i Flyway Council (op. c i t . ) states that their main objective i s to maintain a widely d i s t r i b u t e d population of waterfowl at a s u f f i c i e n t l y high l e v e l so that both hunters and non-hunters can enjoy f u l l y u t i l i z e the resource now and i n the future.  and  In order t o accomplish  this  objective i t w i l l be necessary; to b u i l d up and hold waterfowl populations at a high l e v e l ; to develop and enforce regulations which w i l l ensure a carryover of adequate breeding stock, and to control s u f f i c i e n t habitat to provide  - 3-  for  the needs of waterfowl.  The primary objectives i n the c o n t r o l of habitat  are the maintenance of existing wetland habitat and the creation of a d d i t i o n a l wetlands.  In such programs, food and cover are of primary  importance.  The s c i e n t i f i c study of food habits i s a most e s s e n t i a l t o o l of waterfowl management. eat  There i s a need f o r a better understanding of not only what ducks  during a l l months of the year but also what they eat i n r e l a t i o n to the  foods available to them.  There i s also a need f o r a better understanding o f  the n u t r i t i o n a l requirements o f ducks. Through the years of food habits studies much has been learned about the f a l l and winter foods of ducks but l i t t l e has been learned about t h e i r food habits during the c r i t i c a l breeding and brood r a i s i n g period.  This i s  e s p e c i a l l y true i n the case of the common mallard on the Canadian breeding grounds.  Therefore, the objectives of this  study were; to determine the  spring and summer food of the mallard, and t o determine the r e l a t i o n s h i p between the foods u t i l i z e d and the a v a i l a b i l i t y of them.  HISTORICAL REVIEW  The study of food habits of w i l d l i f e had i t s beginning i n North America i n the l a t t e r part of the nineteenth century.  With the founding of the United  States Bureau of B i o l o g i c a l Survey i n I885 began the intensive professional work on the food habits of b i r d s .  The early work stressed the economic  r e l a t i o n s h i p between b i r d s and man. and i t was not u n t i l a f t e r the s t a r t of the twentieth century that food studies were c a r r i e d out f o r purely b i o l o g i c a l interest. Work on the study of waterfowl food habits began after the turn of the  -u century and the names o f Mabbot, McAtee, Wetmore and Oberholser are prominent among the early workers.  The b a s i s for much of the food habits research i n  l a t e r years has been the data c o l l e c t e d by the Bureau of B i o l o g i c a l Survey. Duck stomachs c o l l e c t e d since 1901 have been analyzed and the data summarized by A. 0 . Martin and F. M. Uhler (1939), who based t h e i r study on 7,998 stomachs, and by Clarence Cottam (1939).  The data r e s u l t i n g from a great many  food studies were brought together and published by A. C. Martin, H. S. Zim and A. L. Nelson  (195D i n t h e i r book "American W i l d l i f e and Plants".  Literature on the food o f waterfowl i s extensive, and at once reveals astonishing s i m i l a r i t i e s i n the techniques used t o evaluate the food materials.  The gizzard contents as an i n d i c a t i o n o f food habits of ducks have  been used almost e x c l u s i v e l y . McAtee (1918) i n his paper on the food habits of mallards s t a t e s :  "A t o t a l of 1,725 gizzards of the mallard, many of them  accompanied by w e l l f i l l e d g u l l e t s , have been examined".  Other workers made  l i t t l e or no use of the g u l l e t contents or attempted t o compare them with the contents o f gizzards (Mabbot, 1920, Martin, and Uhler, 1939, Cottam, 1939). Pirnie  (1935) recognized the importance o f using the g u l l e t contents and  suggested that greater use should be made of the g u l l e t s and l e s s attention paid to the contents of the gizzards. In many studies of the food of ducks, the adequacy of sampling was often f a r from s a t i s f a c t o r y , too often the investigator examined such material as happened to come h i s way and a l l too r a r e l y i s there any evidence that he actually supervised the c o l l e c t i o n of material.  Most o f the duck stomachs  examined were obtained from sportsmen during the hunting season, while c o l l e c t i o n s from other seasons of the year were i n c i d e n t a l .  Summer  c o l l e c t i o n s i n p a r t i c u l a r , are very sparse due to reluctance of b i o l o g i s t s to k i l l or supervise the k i l l i n g o f b i r d s during the breeding season.  - 5 -  STUDY AREA  General Description Location This report describes the work of three summers.  A preliminary year,  I956, was spent studying ponds on a one and one h a l f square mile study block of farmland i n south c e n t r a l Manitoba. 1957  to 1959,  For the three years of investigations,  the study area was enlarged to 100 square miles.  The  area  started two miles south of Minnedosa, Manitoba and extended south f o r ten miles.  The east and west boundaries were f i v e miles on each side of  P r o v i n c i a l Highway No. 10.  Plate I shows the location of the study area.  The general region was chosen because the history of waterfowl use of the area was known from previous investigations.  The study block used i n 1956  was  the center of investigations f o r many years by Evans (1951) and Dzubin (1954).  Geology The region i s from L475 to 1825 fe©t above sea l e v e l with the contours running from the northeast to the southwest.  Ellis  (1938J describes the  region as o v e r l a i n with a t h i c k layer of g l a c i a l t i l l derived from the granites of the Laurentian s h i e l d and limestone from the Lake Manitoba district.  The land surface i s r o l l i n g , the uplands are usually w e l l drained  with the main drainage to the southeast.  Most of the depressions are f i l l e d  with water from melting snows and runoff from the heavy spring r a i n s .  Thus,  water areas are formed which vary i n size from temporary puddles to ponds of ten  or more acres.  The s o i l s are the northern b l a c k earths, predominately  heavy clay loams, formed under the t a l l grass p r a i r i e and aspen groves.  P L A T E I. LOCATION OF MINNEDOSA ONTARIO  SASKATCHEWAN  STUDY  AREA  - 6 -  Land Use  ^  The land use i n the study area was mainly f o r the production of cereal grains of which wheat, barley and oats were the important crops. most farmers r a i s e d small herds of dairy or beef c a t t l e . h a l f square mile study area Evans (op. c i t . ) found i n 1949  In addition,  On the one and one that 57% was under  c u l t i v a t i o n , 11$ used as permanent pasture, 17% was not c u l t i v a t e d and consisted of fence rows, road allowances, aspen groves and f i e l d borders, and the remaining 12% consisted of water or wet areas.  This breakdown probably  holds true f o r the whole study area, although no attempt was made to determine the actual acreages involved.  Upland Cover The vegetation of the study block varied considerably due to the e f f e c t s of land use and to the influence of the slope on temperature and s o i l moisture. The following description i s based to a large extent on information from B i r d (1930) and Evans (op. c i t . ) with some modifications. Woody growth consisted mainly of aspen (Populus tremuloides Miehx.), while burr oak (Onerous mac roc ar pa Michx.) was found on the d r i e r s i t e s with a southerly exposure.  The aspen groves were generally surrounded by a shrub  zone made up of one o r more of the following shrubs; snowberry  (Symphoricarpos  albus (L.) Blake), choke-cherry (Prunus v i r g i n i a n a L . ) , saskatoon (.Amelanchier sp.), and cranberry (Viburnum trilobum Marsh.).  On the ungrazed,  wet s i t e s , between the aspens and the emergent vegetation, there was either a border of grasses, rushes (Junous b a l t i c u s Willd.) and sedges (Carex sp.) or a zone of willows (Salix sp.). B i r d (op. c i t . ) states that the willow zone i s present where there i s no concentration of alkaline s a l t s , but where such  - 7-  s a l t s are present the succession i s d i r e c t l y from marsh to p r a i r i e . Drought conditions during the summers of 1958 formation of large areas of dried mud areas.  and 1959  resulted i n the  f l a t s around most of the exposed water  F i r s t to colonize the open f l a t s was the marsh ragwort (Senecio  congestus  (R. Br.)  DC var. p a l u s t r i s (L.) Fern.).  on the study area i n 1958  and by 1959  The ragwort was f i r s t  found  i t had become the dominant plant along  the borders of drying ponds.  Water Areas The r o l l i n g t e r r a i n of the Minnedosa region i s i d e a l l y suited f o r the natural creation of small ponds.  From a e r i a l photographs taken of the region  by the United States F i s h and W i l d l i f e Service i n the spring of 1959 estimated that there were some block.  i t was  10,000 water areas i n the 100 square mile study  Because of the amount of equipment used i n the study of the ponds,  only the roadside water areas, accessible by car, were used.  Out of a t o t a l  of 220 miles of road allowances i n the study area, 161 miles were passable by car;  an estimated  2200 ponds were located along these.  I t was from t h i s  population of water areas that the samples were chosen. The size and shape of the ponds was the contours o f the land.  extremely v a r i a b l e and depended upon  Water depth was also v a r i a b l e and was not only  dependent upon the contours but also upon the gain or loss o f water during the season.  In natural areas the maximum depth encountered was eight feet whereas  i n a r t i f i c i a l areas maximum depths o f eighteen feet were common. depth of a l l ponds studied was 1.3  The mean  feet.  Extreme v a r i a t i o n i n water levels from abnormally high waters i n 1955 drought conditions i n 1959,  had a profound e f f e c t on the pond vegetation.  to  - 8 -  Areas with t h i c k stands of emergent plants were denuded by flood conditions. The plant communities were unable to recolonize the ponds when the waters receded, with the r e s u l t that the ponds i n 1959 were mostly free of emergent plants and were surrounded by large mud  flats.  The emergent vegetation of the  ponds was varied and i n some ponds, whole communities changed during the study. However, i n general, the dominant species were whitetop (Scolochloa festucacea (Willd.) Link) sedges (Carex sp.), c a t t a i l (Typha l a t i f o l i a L . ) , bulrush (Scirpus acutus Muhl., S. paludosus Nels., S. Validus Vahl.) and reedgrass (Phragmites communis T r i n . ) . The ponds supported a variety of f l o a t i n g and submerged plants of which the following were the most common; duck weeds (Lemna t r i s u l c a L., L. minor L . ) ; m i l f o i l ,  (Myriophyllum exalbescens Pern.); White water-crowfoot,  (Ranunculus subrigidus W. B. Drew); hornwort, Ceratophylium demersum L . ) ; mare's t a i l ,  (Hippuris v u l g a r i s L . J ; pond-weeds, (Potamogeton sp.J;  bladderwort, ( U t r i c u l a r i a v u l g a r i s L . ) . The large green algae, Chara sp. and a smaller, filamentous green algae were also important members of the pond communities.  METHODS  Pond Studies A study o f the faunal c h a r a c t e r i s t i c s o f small p r a i r i e ponds was i n i t i a t e d i n 1956 months. 1957  to determine the changes that occur during the summer  Two ponds were chosen f o r weekly and four f o r bi-weekly studies.  a one hundred square mile study area was established.  sampled i n 1956 were again sampled weekly i n both 1957  In  Four of the ponds  and 1958,  and i n  - 9 -  addition, ponds randomly selected from the study area, were examined once.  In  1959 a l l of the ponds examined were randomly selected from the study area. Table 1 summarizes the ponds studied during the four years of the i n v e s t i g a t i o n .  Table 1.  Ponds studied i n the Minnedosa study area, 195° to 1959 Number o f d i f f e r e n t ponds studied  Year  Weekly  Bi-weekly  T o t a l pond samples  By random selection  1956  2  4  0  44  1957  U  0  7  53  1958  u  0  19  76  1959  0  0  43  43  TOTAL  u  4  69  216  The random s e l e c t i o n of study ponds was f a c i l i t a t e d by the use of four figure random number groups.  The study area was on an established one mile  g r i d and the perimeter o f each block was divided into e i g h t , one h a l f mile sections.  A four number group, taken from a table of random numbers, referred  to a preeise l o c a t i o n along the perimeter o f a section of l a i d .  The f i r s t two  numbers of the group indicated the square mile block; the t h i r d number, the section of the perimeter; and the l a s t number, the distance to the nearest corner.  Water areas accessible by car, i n the locations indicated by random  numbers, were used as the study ponds. Methods used i n the study of ponds f e l l into two categories;  - 10 -  determination o f the composition of vegetation i n and around the water area and determination of the composition of the fauna.  Vegetation Several techniques for surveying tiie emergent and shoreline vegetation were t r i e d i n 195°  and 1957.  The method that appeared most suitable and used  during the balance of the study was e s s e n t i a l l y the l i n e - p o i n t method described by Dasmann (1951).  Transects were run at r i g h t angles to the shore  and extended from the edge of the open water to a point ten feet above the spring high water mark.  The frequency of transects depended to a large extent  upon the length of the shoreline and the v a r i a b i l i t y of the plant community. Normally the transects were run at no l e s s than f i f t y foot and no more than two hundred foot i n t e r v a l s around the edge of the water area.  This technique  varied i n ponds with vegetation throughout, i n which cases, the transects were continued through the areas.  Points were located one foot apart and the  dominant plant, or c l a s s of cover d i r e c t l y under the foot mark, was  recorded.  Submerged vegetation was not surveyed because of the lack of an adequate technique, however, the species of submerged plants were recorded f o r each pond.  Fauna The macroscopic  animals which l i v e on the bottom and those which l i v e i n  association with plants were sampled with the aid of a six inch Ekman dredge. Dredgings were taken i n multiples of four from the shallow waters along the shore aid from the deeper waters near the centers of ponds.  Each group of  four dredgings was combined to form a sample equivalent to one square foot of  - 11 -  bottom.  The samples were washed through a 30 i 28 mesh screen and the  organisms were sorted, i d e n t i f i e d , counted and preserved f o r further study i n the laboratory. To f a c i l i t a t e the sorting of the animals from the debris, the washed samples were immersed i n a sugar solution with a s p e c i f i c gravity of 1.110, the organisms f l o a t e d to the surface and were screened o f f for identification.  With t h i s method i t was possible to recover as many as 95% of  the organisms, whereas, i n hand picking only 79$ were recovered (Dobie, 1958).  Food Studies Sampling  Statistics  To e s t a b l i s h the food habits of mallards, the number of stomachs needed for analysis i s a problem which must be overcome before the sampling i s completed.  Where the ducks are eating several foods, a d i f f e r e n t size sample  i s required f o r each item of food.  In t h i s study, therefore, the emphasis was  placed on the use of two major foods, animal and plant. Cochran (1956) suggests the following formula f o r estimating the size of sample required: n  Where n i s the sample s i z e , s i s the standard deviation of the amount of one food consumed by the population and L the allowable error.  From the sample of  41 adult mallards c o l l e c t e d i n 1957, the standard deviation f o r both plant and animal foods u t i l i z e d was 43.2$; the allowable error of the estimate a r b i t r a r i l y set at 10%.  Based on these data the sample size required was  estimated at 74 ducks with food i n t h e i r g u l l e t s .  The allowable error would  have to be increased i f a smaller sample i s used or i f the sample i s subdivided.  was  - 12 -  Waterfowl C o l l e c t i o n s The information on food habits of mallards i s based on 346 b i r d s c o l l e c t e d during the spring and summer months over a three year period, 1957 to 1959•  Most of the b i r d s were shot, some were caught by hand and others  were obtained from banding operations i n the study area.  During the f i r s t  year, b i r d s were taken whenever possible, however, i t was evident that the number o f b i r d s with food i n their g u l l e t diminished during the midday. Therefore i n the following years, c o l l e c t i o n s were made mainly i n early morning and evening.  The roads i n the study area were driven and an attempt  was made t o shoot the mallards encountered. found an attempt was made to obtain both.  In a l l cases, where p a i r s were S i m i l a r i l y , when groups were found  an attempt was made t o obtain two from.the group.  Table 2 summarizes the  c o l l e c t i o n s of mallards during the three year period.  Table 2.  Mallards c o l l e c t e d on Minnedosa study area, 1957 to 1959 Ducks c o l l e c t e d with food i n g u l l e t s  Year  :  T o t a l ducks c o l l e c t e d —  ; :  Adults  Young  1957  41  14  1958  4  1959 TOTAL  Total  Adults  Young  Total  55  89  31  120  31  35  17  70  87  51  17  68  105  34  139  96  62  158  211  135  346  In 1957 and 1958 the stomachs were not removed from the b i r d s u n t i l after the hunting was f i n i s h e d , usually anywhere up to three hours l a t e r .  In  - 13 -  examining the stomachs i t was found that i n some, deterioration of the g u l l e t contents, e s p e c i a l l y the soft bodied animals, had taken place.  During the  l a s t year o f c o l l e c t i n g , the stomachs were removed and f i x e d i n 35% isopropyl alcohol as soon as the b i r d s were k i l l e d . In t h i s study, foods found i n the two anterior regions of the alimentary canal were used t o determine feeding habits. the  The muscular grinding chamber of  canal i s termed the gizzard and the region anterior to the gizzard, i s  termed the g u l l e t .  The g u l l e t includes the mouth c a v i t y , oesophagus and  proventriculus (Henderson, 1939). In the laboratory examination o f stomachs, the foods found i n the g u l l e t were kept separate from the foods found i n the gizzard.  The g u l l e t foods were  sorted, i d e n t i f i e d , enumerated and the volumes measured by displacement of water.  The proportions of the food items were then determined f o r each  individual.  The g u l l e t was considered empty only when there was l e s s than  m i l l i l i t e r s of food present.  0.2  The gizzard contents, on the other hand, were  sorted and i d e n t i f i e d only. An e f f o r t was made to i d e n t i f y each item of the organic contents regardless o f the amount found. i d e n t i f i e d to species.  Where possible, the items of plant foods were  Most of the seeds were i d e n t i f i e d by the Plant  Products D i v i s i o n of the Canada Department of A g r i c u l t u r e . were taken from Gray's Manual of Botany  (Fernald, 1950).  The technical names Animal foods were  i d e n t i f i e d by myself t o class and order, or i n the case of some insects, to family.  The technical names used were taken from "Fresh-water Invertebrates  of the United States" (Pennak, 1953)  and "An Introduction to Entomology"  (Comstock, 1950). A McBee Keysort card was made out f o r each b i r d c o l l e c t e d .  On the card  -Li-  the relevant c o l l e c t i o n data and stomach contents were recorded and coded.  In  cases where food was found i n both the g u l l e t and gizzard, duplicate cards were made out, one with the g u l l e t contents coded and the other with the gizzard contents coded.  RESULTS  C h a r a c t e r i s t i c s of Vegetation The ponds encountered constructed by man melting snows.  i n the study area were of two general types; those  and those formed i n the shallow depressions by rains and  The a r t i f i c i a l ponds or dugouts, were constructed mainly  during the drought years of the 1930's to serve f o r stock watering  purposes.  Since then, many of the dugouts have overflowed at the ends so that at least two of t h e i r sides are no longer steep and support a dense growth of vegetation. The n a t u r a l ponds were i n the various stages of succession, progressing from an open water habitat to a grassland or a wooded habitat. The change i n vegetation i s the normal hydrarch succession described by Weaver and Clements (1938) i n which the submerged plants are replaced by f l o a t i n g plants and emergent vegetation i n the shallow waters, these i n turn give way  to the sedge  meadow types along the moist shoreline. Any stage, and usually a l l , can be found i n a single natural pond.  The stages appear to be arranged i n more or  less p a r a l l e l zones radiating from the margins.  The a r t i f i c i a l ponds or  dugouts were also undergoing successional changes, although i t was more evident i n some dugouts, which were older or f i l l i n g more rapidly due to erosion, than i n others.  - 15 -  The successional stages and even the d i r e c t i o n i n which they are proceeding may be affected by land use and water l e v e l s .  During the long  drought period i n the 1930's most of the ponds i n the Minnedosa area were used as a source of hay far c a t t l e , while some of them were c u l t i v a t e d and planted. Even during years of normal water l e v e l s , c u l t i v a t i o n almost to the water's edge and shoreline grazing by c a t t l e has a marked affect on the plant communities.  Water l e v e l s i n the ponds can vary considerably over a short  period of time and may be an important factor i n determining the successional stage or the d i r e c t i o n of the succession. The successional changes a f f e c t the animal communities as w e l l .  Indeed,  the whole b i o t i c community undergoes a gradual change which arises from an i n t e r a c t i o n within the b i o t i c community, from physical changes outside the community, or from a combination of the two.  A l l e e , et a l . (1949) .state that  the r e s u l t of the community succession i s a gradual a l t e r a t i o n o f the community through time, and the appearance of species populations better adjusted to the changed conditions.  Pond C l a s s i f i c a t i o n From work i n the Minnedosa area, Evans (op. c i t . ) suggested a method f o r c l a s s i f y i n g water areas by the permanence of the water and by the plant community.  The ponds were divided into ten classes consisting of four major  groups as shown i n Table 3«  The two groups which contained emergent  vegetation were further divided according to t h e i r plant community.  This  c l a s s i f i c a t i o n , which was based on normal water l e v e l s , i s used for comparative purposes.  Areas which were c l a s s i f i e d as semi-permanent during  - 16 -  normal years became indistinguishable from permanent areas during the wet cycle (Plates I I to V I ) .  S i m i l a r i l y , some permanent areas were dry i n 1959  whereas, some of the semi-permanent ponds contained an abundance of water.  Table 3.  Types of ponds found i n the Minnedosa study area (from Evans, 1951) A.  Permanent ponds 1. Whitetop-sedge 2. Gattail 3. Bulrush 4. Mixed emergents or denuded  B.  Semi-permanent ponds 1. Whitetop-sedge 2. Gattail 3. Bulrush 4. . Mixed emergents or denuded  C. . Temporary ponds D.  Dugouts without flooded ends  On a one and one half square mile block i n the middle of the Minnedosa study area, Evans (op. c i t . ) recorded 127 ponds.  Of these, 33% were  c l a s s i f i e d permanent, 41% semi -permanent, 24% temporary and 2% dugouts.  He  did not record the number of ponds that went dry but presumably 65%, the temporary and semi-permanent ponds, would have been dry by the end o f summer. Ponds i n the study area were counted i n August 1957  and none were dry.  An  early August count i n 1958 showed 66% of the ponds dry and i n 1959 the number had reached 80%.  The number of ponds d i d not vary appreciably from spring to  spring because there was enough runoff each year to at l e a s t p a r t i a l l y r e f i l l the water areas.  - 17  When i t became apparent i n 1957  that a vast change i n vegetation  taking place, a sample of ponds was  was  chosen and c l a s s i f i e d according to the  Table 4 summarizes the yearly samples as compared to the  vegetation type.  findings of Evans i n  Table 4«  -  1949.  C l a s s i f i c a t i o n of ponds i n Minnedosa study area Percentage of ponds i n each c l a s s i f i c a t i o n  Year  ;  Whitetopsedge  1949 1957 1958 1959  I t was not u n t i l 1959  67 44 47 19  .  Cattail  Bulrush  Mixed or denuded  13 15 16 4  8 15 11 7  12 26 26 70  that the whitetop-sedge associations were  noticeably affected and reduced i n number.  What the sample does not show are  the densities of the plants within the associations, this was not measured i n a large enough sample to be of any value.  The stands of emergent vegetation,  p a r t i c u l a r l y whitetop and sedge, were considerably thinner during the period of unstable water conditions than they were during the period of normal or r e l a t i v e l y stable water l e v e l s .  Factors A f f e c t i n g Plant Communities During the study the most important  factor a f f e c t i n g the plant  communities was the f l u c t u a t i o n i n water l e v e l s .  Under normal conditions,  with water levels receding as much as twelve inches during the summer, dense  - 18 -  stands of vegetation form i n the water and along the shores of ponds.  The  sudden increase i n water l e v e l s i n 1955, flooded beyond the normal high water mark and into the upland cover.  With prolonged flood conditions the upland  plants gradually died out and were replaced by species better adapted to the wet s i t e .  An increase i n water l e v e l may also affect both emergent and  submergent vegetation, e i t h e r d i r e c t l y , or i n d i r e c t l y by an increase i n wave action or t u r b i d i t y . The vegetative character and thus the c l a s s i f i c a t i o n of a pond, changes with prolonged periods of high water l e v e l s .  For example, a c a t t a i l pond with  an outer zone o f whitetop grasses and sedges can change to a whitetop-sedge pond i f the c a t t a i l zone i s k i l l e d by an increase i n water l e v e l .  A prolonged  period of high water may continue to a l t e r the vegetation to a mixed or denuded c l a s s i f i c a t i o n .  Plates I I to VI i l l u s t r a t e changes that occurred from  1954 to i960, i n the plant associations of three ponds. Plate I I shows one semi-permanent and two permanent c a t t a i l ponds as they appeared under normal conditions i n the spring of 1954.  The inner band of  emergent vegetation, along the open water, was a c a t t a i l association.  Mixing  with the c a t t a i l s and merging with upland cover above the shore was a whitetop-sedge association.  The flooded end of the dugout supported a dense  growth of sago pondweed (Potamogeton pectinatus L.) i n the open water. Increased water l e v e l s i n 1955 (Plate I I I ) , resulted i n the three ponds joining to form a single water area.  The c a t t a i l s were surrounded with water  and began to show signs of dying out, while the shoreline association of  ;  whitetop and sedge flourished under t h e new conditions.  High waters  continued; i n 1956 the c a t t a i l s disappeared as the dominant emergent plants and were replaced by the shoreline zone of whitetop-sedge.  The sago pondweed  PLATE II  May 1954* Three cattail ponds during a period of normal water levels. The upper i s a semi-permanent pond and the lower two are permanent ponds. The pond in the lower right is a flooded dugout. PLATE I I I  July 1955. During the f i r s t year of flood conditions the three ponds joined and the cattail association showed signs of dying out.  - 19 -  bed was reduced to only a few small clumps.  By the spring of 195& (Plate TV)  a l l emergent vegetation had disappeared and only a narrow band o f whitetop and sedge remained along the shore.  The waters began to recede and by l a t e summer,  the exposed mud f l a t s were covered with the seedlings o f grasses and sedges. Spring runoff was l i g h t i n 1959 and water l e v e l s continued to recede.  By  midsummer (Plate V) the three ponds were again separate with one dry.  The  sedge and grass seedlings of 1958, were replaced by a band o f marsh ragwort (Senecio congestus var. p a l u s t r i s ) , b e t t e r suited t o the high s o i l a l k a l i n i t y . At the end o f the summer o f 1959, only the flooded dugout contained water and the newly bared mud f l a t s were covered with sedge, whitetop and c a t t a i l seedlings. level.  A high spring runoff i n i960 r e f i l l e d a l l three ponds to the 1954  The vegetation growing on mud f l a t s thrived under the new water  conditions and by early summer (Plate VI) formed a dense zone around the shore. In  late summer the three ponds again resembled  the 1954 condition; the  c a t t a i l s , however, had not f u l l y recovered and were not as abundant.  Seed Production and A v a i l a b i l i t y In  food studies i t i s not enough to determine seed production without  considering the a v a i l a b i l i t y of the seeds.  This i s p a r t i c u l a r l y true i n the  study of spring and summer foods of ducks where the seeds produced i n the f a l l must be available i n the spring to be of any value.  No s a t i s f a c t o r y method  was found f o r determining the r e l a t i v e a v a i l a b i l i t y of seeds i n the spring, therefore, no quantitative data are presented. The a v a i l a b i l i t y of seeds depends on when they are shed from the parent plant and the nature of the understory on which they f a l l .  Whitetop and  sedges produce and shed large quantities of seeds i n l a t e summer.  The parent  PLATE IV  May 1958. After three years of high water l e v e l s the c a t t a i l association completely disappeared leaving a whitetop-sedge association along the shore.  PLATE V  July 1959. By midsummer of the f i r s t year of drought conditions the upper pond was dry and the two lower ponds were surrounded by large areas of bare mud.  PLATE VI  May i960. With the return of normal water conditions the three water areas assumed separate i d e n t i t i e s as whitetop-sedge ponds.  - 20 -  plants on land, for the most part, remain standing u n t i l the new growth takes over i n the spring.  The understory, therefore i s usually quite sparse and the  seeds are r e a d i l y available i n early spring.  Seeds shed by whitetop and sedge  i n water may or may not be available the following spring depending on water depth and nature of the bottom.  The seeds of bulrush and spikerush mature i n  l a t e summer but most remain on the dead plant u n t i l spring when they are r e a d i l y available to the ducks.  The a v a i l a b i l i t y of the seeds o f the  submerged plants, l i k e those of emergent plants, i s dependent upon the water depth and the nature of the bottom. Under c e r t a i n conditions, some upland plants produce vast quantities of seeds which are available t o the ducks.  Lamb's quarters  (Chenopodium  album L . ) , which sheds i t s seeds i n the spring, was very abundant i n the roadside ditches and shallow ponds that were dry i n 1958.. When these areas were p a r t i a l l y r e f i l l e d by the 1959 runoff, the waters and shores were covered with seeds.  Thus, lamb's quarters was probably the most abundant o f the  available, non-cultivated seeds i n 1959. Waste c e r e a l grains were usually a v a i l a b l e throughout the season. were available i n the f i e l d s before  They  spring c u l t i v a t i o n was complete and along  the roads a f t e r the f i e l d s were worked.  The roadsides were probably the best  source o f seeds, not only because they supplied an almost constant  source o f  cereal grains but also, because they supplied most of the gravel required by the ducks.  C h a r a c t e r i s t i c s of Fauna The  animals which were c o l l e c t e d by dredge are r e f e r r e d to as bottom  fauna and are divided into two categories; center fauna are those which were  - 21 -  taken from the center of ponds or i n water of more than two feet i n depth and edge fauna are those which were taken from the shallow waters along the edges of ponds.  The habitat of the two sampling areas was d i f f e r e n t ; the center  habitat consisted mainly of submergent vegetation growing i n s i l t and plant debris i n an advanced stage of decomposition.  The shoreline habitat, on the  other hand, consisted mainly of emergent vegetation growing i n an area usually covered with dead plant materials i n early stages of decomposition.  Differences i n Center and Edge Samples There was no apparent difference i n the t o t a l number of center and edge fauna c o l l e c t e d from ponds i n 1957 and 1958 but there was a s i g n i f i c a n t difference i n 1959• However, considering a l l bottom samples c o l l e c t e d during the study, a s i g n i f i c a n t difference i n abundance of center and edge organisms i s indicated.  The calculated value o f " t " i s 2.75 as compared to the table  value of I.96 at the G.05 l e v e l (Snedecor, 1956). Table 5.summarizes the  Table 5.  Comparison o f the abundance of. organisms i n center and edge samples c o l l e c t e d from ponds i n 1957, 1958 and 1959  Center samples  Edge samples  Value of «t"  Year Number of organisms  Limits of confidence 0.05 l e v e l  n  Number of organisms  Limits of confidence 0.05 l e v e l  1957 1958 1959  275-7 317.5 404.4  96.8 86.0 H5.9  53 76 A3  192.8 274.8 125.6  54-5 103.9 75.4  43 76 43  I.40 0.62 3.86  Mean  326.3  59.4  172  213.4  53.7  162  2.75  n  - 22 -  s t a t i s t i c s of the bottom fauna samples taken from the center and edge locations during the period of study. The difference i n habitat between the shore and center of the ponds i s r e f l e c t e d i n both the r e l a t i v e abundance and the variety of organisms found i n the two locations.  Table 6 summarizes the bottom fauna c o l l e c t i o n s made on  ponds i n 1957.  and 1959.  1958  Although a l l groups of organisms were  represented i n both the center and shoreline samples, they were found i n  Table 6.  Summary of bottom fauna c o l l e c t i o n s from l 6 l ponds i n 1957.  1958  1959 Number of organisms per square foot of bottom Organism Center samples Mean ANNELIDA Hirudinea  Per cent  Edge samples Mean  Per cent  1.8  0.6  1.8  0.8  45.9  14.1  85.5  40.1  0.5  0.1  0.5  0.2  3.9 1.6 0.4 8.4 1.3 255- 0  1.2 0.5 0.1 2.6 0.4 78.2  0.9 1.2 1.5 4.1 7.0 100.2  0.4 0.6 0.7 1.9 3-3 47.0  MOLLTJSCA Gastropoda  7.5  2.3  10.7  5-0  TOTAL NUMBER OF ORGANISMS  326.3  ARTHROPODA Crustacea Amphiopoda Arachnoidea Hydracarina Insecta Ephemeroptera Odonata Hemiptera Trichoptera Coleoptera Diptera  213.4  and  - 23 -  d i f f e r e n t proportions. Tendepedidae  (DipteraJ larvae composed ?8-2% of the  center fauna but only 47.0% of the edge organisms.  Trichoptera larvae, while  usually found i n association with plants, were more abundant i n the center samples.  They were found to overlap the two zones and. generally appeared i n  greatest numbers on the open water side of the emergent vegetation. The Amphiopoda obtained i n bottom sampling was represented almost e n t i r e l y by a single species, H y a l e l l a azteca (Saussure). ponds and made up 40.1% o f the edge fauna. high population of H y a l e l l a , as many as  I t was a common animal i n the One pond i n 1957 bad an extremely  56OO individuals were removed from a  one square foot sample.  Annual Changes The changes i n water l e v e l s during the study had l e s s a f f e c t on the abundance of bottom fauna than one would expect.  The only s i g n i f i c a n t  difference (0.05 l e v e l ) i n numbers of organisms, occurred i n the edge samples  Table 7«  Students' " t " values o f bottom fauna abundance i n ponds i n  1957-1958, 1957-1959 and 1958-1959 Center samples Year  Edge samples  Total  ;  Value of "t"  n  Value of "t"  n  Value of "t"  n  1957-1958  0.63  129  1.12  119  1.20  248  1957-1959  1.64  96  1.57  86  0.54  182  1958-1959  1.02  119  2.01  119  0.61  238  - 24 -  between the years  I958 and 1959. The r e s u l t s of Students' " t " test to  determine i f s i g n i f i c a n t changes i n bottom f a i n a occurred between the years are summarized i n Table 7., Although the pond habitat changed noticeably as a r e s u l t of variations i n water l e v e l s , the o v e r a l l abundance of bottom fauna did not change.  Certain  i n d i v i d u a l groups of organisms however, were affected by the change i n habitat. For instance, Odonata, which depend upon emergent vegetation, decreased i n numbers along the pond edges and Coleoptera increased as t h e i r habitat of dead  Table 8.  Bottom fauna c o l l e c t e d from centers and edges of ponds i n 1957, 1958  and I959  Number of organisms per square foot o f bottom Organism Edge samples  Center samples  ANNELIDA Hirudinea ARTHROPOBA Crustacea Amphiopoda Arachnoidea Hydracarina Insecta Ephemeroptera Odonata Hemiptera Trichoptera Coleoptera Diptera MOLLUSCA Gastropoda  TOTAL NUMBER OF ORGANISMS  1957  1958  1959  Mean  1957  1958  1959  Mean  1.8  2.5  0.4  1.8  3.0  1.9  0.3  1.8  10.2  85.7  19.6  45.9  37.8  135.4  45.1  85.5  0.2  0.6  0.6  0.5  0.9  0.3  0.5  0.5  8.1 3-9 0.7 0.5 2.1 1.0 1.6 1.7 0.1 0.4 0.4 0.3 8.4 5-4 7.5 13.8 0.8 1.3 1.9 1.3 246.2 203.8 356.5 255.0 8.7  5.7  9.4  7.5  275-7 317-5 404.4 326.3  1.7 0.3 0.9 2.5 2.6 1.4 9.2 2.7 5.0 7.3 101.4 120.7 27.8  5-2  tr 0.9 0.2 1.2 0.6 1.5 4-1 1-5 11.0 7.0 62.5 100.2  3.6  10.7  192.8 274.8 125.6 213.4  - 25 -  plant material improved.  Table 8 summarizes the bottom fauna c o l l e c t i o n data  for the three years of study.  Seasonal .Changes Throughout  the spring and summer season marked changes i n the abundance  of fauna were noted.  The precise timing of the periods of abundance i s  c h a r a c t e r i s t i c of each pond but the pattern of changes are s i m i l a r .  Following  the departure of i c e cover i n A p r i l there was a gradual increase i n the bottom fauna to a peak i n the l a t t e r part of May.  The spring peak was followed by a  s l i g h t depression i n abundance then a marked increase u n t i l a summer peak was reached i n mid August.  The number of organisms then gradually decreased u n t i l  the ponds became frozen i n the f a l l .  The seasonal changes are best  i l l u s t r a t e d i n the following graphs:  Figure 1 shows the changes i n center  samples; Figure 2 the changes i n edge samples and Figure 3 i s a composite picture of the changes that occurred i n center and edge samples i n 1957 > 195& and 1959-  The data from which these graphs were drawn are presented i n  Appendices 1,  2 and 3«  A v a i l a b i l i t y of Bottom Fauna The a v a i l a b i l i t y o f bottom fauna depends not only on the abundance of" the organisms, but also, on the d i s t r i b u t i o n of the fauna i n the*ponds and the water depth at which they occur.  The center samples were taken i n water of  usually more than two feet i n depth and edge samples, from less than two feet. Because the mallards obtain t h e i r food from the shallow waters, the edge organisms were considered to be the most important source of animal foods. The d i s t r i b u t i o n of the edge fauna was variable i n the study area; a l l  FIGURE I.  BIWEEKLY  ORGANISMS P E R 1958  8  1959.  C H A N G E S IN  SQUARE  FOOT,  THE  NUMBER  CENTER  OF  SAMPLES  BOTTOM 1957,  FIGURE BOTTOM 1957,  BIWEEKLY  2.  1958  ORGANISMS  a  1959.  CHANGES PER  SQUARE  IN  THE FOOT,  NUMBER EDGE  OF  SAMPLES  |y CONFIDENCE  3.  LEVEL  l  l  I  l  1  1  MAY  MAY  JUNE  JUNE  JULY  JULY  AUGUST  1-15  16-31  1-15  16-30  1-15  16-31  1-15  THE  NUMBER  i  FIGURE  LIMITS 0.05  BIWEEKLY  B O T T O M  ORGANISMS  CENTER  AND  EDGE  CHANGES PER  IN  SQUARE  S A M P L E S  FOOT OF  1957,  IN 1958  OF  THE a  1959.  - 26 -  groups of organisms were not represented i n each pond and the variations were even more marked as habitat conditions changed.  One would expect such changes  i n d i s t r i b u t i o n to take place as the ponds changed from heavy emergent plant cover i n 1957  to open water i n 1959.  The organisms which were dependant upon  emergent vegetation became less widely d i s t r i b u t e d during the study. instance, the Odonata were found i n 51.0% of the ponds i n 1959.  of the ponds i n 1957  For  and only  16.3%  Hemiptera and Trichoptera apparently underwent a  similar change, but as they were less dependant upon emergent vegetation than were Odonata, the change was not as marked.  Organisms such as Diptera and  Coleoptera were affected less by the change i n habitat than were the other Figure 4 i l l u s t r a t e s the changes i n d i s t r i b u t i o n of edge fauna  organisms. from 1957  to 1959•  The data from which Figure 4 was drawn are presented i n  Appendix 4-  Use of Study Area by Waterfowl  Populations Breeding pairs - The Minnedosa area has been the scene of waterfowl research for many years but there are no comparable annual estimates of waterfowl populations i n the general area.  Each research worker c a r r i e d out population  counts to s u i t h i s own needs and the r e s u l t s are not, i n most cases, comparable.  As a r e s u l t , one has to depend upon the a e r i a l surveys c a r r i e d  out by the U.S. F i s h and W i l d l i f e Service for population indices.  Although  the population data f o r pothole habitat are drawn from a sample of the 10,368 square miles of pothole habitat i n Manitoba, the indices do give an indication of population trends on the study area.  The population indices f o r the  PER CENT OF STUDY PONDS ORGANISM  1957 25  50 i  1958 75 i  IOC  25  50 i  1959 75 i_  25  100  i_  50  75  100 i_  HIRUDINEA AMPHIOPODA HYDRACARINA EPHEMEROPTERA  1  ODONATA HEMIPTERA TRICHOPTERA COLEOPTERA DIPTERA GASTROPODA  FIGURE 4.  OCCURRENCE  OF  EDGE  FAUNA  IN  STUDY  PONDS IN  1957, 1958  a  1959.  - 27 -  pothole habitat (Stratum A) of Manitoba and the sources of the data are summarized i n Table  Table 9.  9.  Summary of a e r i a l survey data for pothole habitat (Stratum A) i n Manitoba Pairs per square mile Year  Authority A l l species  1954-1956 Mean  Mallards  36.6  14«9  Evans  1956  Hanson Hanson Evans Evans  1957 1958 1959  1957 1958  40.5 54-2  21.7 27.2  1959  33.7  15.2  i960  A e r i a l survey data provide an index to the population and not the true population; the proportion of the population that i s seen from the a i r i s unknown and no doubt v a r i e s considerably with habitat types.  Providing the  habitat does not change d r a s t i c a l l y from year to year, the proportion seen from the a i r should remain the same.  In pothole habitat the main features  l i m i t i n g the v i s i b i l i t y of a e r i a l survey crews are the wooded areas around the ponds.  As these did not change i n 1959  the proportion of the population seen  i s comparable to previous years. Ground waterfowl surveys were c a r r i e d out on the 1^ square mile study area from 1952  to 1956  waterfowl populations.  and data from these provide a b e t t e r picture of Ground surveys, l i k e a e r i a l surveys, do not provide  complete population figures but the proportion of b i r d s seen from the ground i s higher.  Table 10 (Cram, 1956)  summarizes the surveys from. 1954  to  1956.  - 28 -  Table 10.  Summary o f ground survey data for 1^ square mile Roseneath study area P a i r s per square mile  Year  1954 1955 1956  1954-1956 Mean  A l l species  Mallards  97.8 73.7 104.1 91.9  27.3 22.0 24.7 24.7  I t i s apparent from Table 9 that neither the t o t a l duck population nor the mallard population changed appreciably during the study.  As the a e r i a l  surveys are designed t o measure population fluctuations of 20% or greater the only s i g n i f i c a n t change i n mallard numbers from the i n 1958.  1954-1956 mean, occurred  The ground survey data indicate a mean population o f 24.7 mallard  pairs (Table  10) per square mile during the 1954-1956 period.  Therefore,  assuming that the Roseneath study area i s representative o f the 100 square mile area, the minimum mallard population on the area i n 1957 aad 1959 was 24.7 breeding p a i r s per square mile and probably almost double that figure i n  1958.  Broods - Population indices f o r waterfowl broods i n the Minnedosa area are, l i k e breeding p a i r s , available from a e r i a l surveys of Manitoba and from ground counts made i n the Roseneath study area. the years 1954 to 1959.  Table 11 shows the brood indices f o r  The period 1954 to 1956, taken from Cram (1956),  covers ground surveys i n the Roseneath study area, whereas the period 1957-  1959> taken from Evans (i960), covers a e r i a l surveys of pothole habitat i n Manitoba.  - 29 -  Table 11.  Summary o f waterfowl brood surveys i n Manitoba 1954 to 1959  Broods per square mile Authority  Year All 1954 1955 1956 1954-1956 Mean 1954-1956 Mean 1957 1958 1959  species 30.7 43.4 50.7 41.6 4.5 1 5.4 9.2 4.8  Mallards 6.0 11.3 12.0 9.3 XX  Cram Cram Cram Cram  1956 1956 1956 1956  Evans Evans Evans Evans  1957 1959 1959 i960  x these indices are the sum o f the brood and late nesting indices xx data not available f o r i n d i v i d u a l species  Examination of Table 11 indicates that there was a gradual increase i n the number o f broods i n the Roseneath area from 1954 to 1956.  This increase  probably c a r r i e d into 1958 when a peak was reached, then dropped sharply i n 1959.  Evans (1959) f e l t that the apparent increase i n 1958 was due i n part to  increased v i s i b i l i t y as a result of the lack of emergent vegetation.  However  there was an increase i n broods i n 1958 but i t was not as high as the figures show.  Another i n d i c a t i o n of an increase i n production i n 1958 was the number  of ducklings that reached the Class II and I I I stages.  The average size o f  Class I I and I I I broods was 5 . 6 ducklings i n 1 9 5 7 , 6 . 6 i n 1958 and 5 . 4 i n 1959-  The average brood size f o r the three years was 5 . 7 ducklings. In summary, one could say that i n both breeding p a i r s and production of  young, there was an increase from 1957 to 1958 and a decline i n 1959*  Th©  increase i n 1958 was probably caused by a movement of waterfowl from the drought areas to the more stable pothole habitat.  By 1959 the pothole habitat  - 30 -  was also.affected by drought and although the i n f l u x of waterfowl was high, the habitat was not able to accommodate as many b i r d s as during the previous year.  Movement of Waterfowl Adults - During a normal spring i n the pothole region of Manitoba the f i r s t mallards arrive at the beginning of A p r i l ; the main f l i g h t i s i n the area three weeks l a t e r .  The return-of waterfowl does not herald the end of winter,  indeed, the ponds may in f i e l d s .  s t i l l be frozen with open water occurring on the ice or  The ponds normally open by mid A p r i l and are ice free when the  main f l i g h t of waterfowl arrives on the breeding grounds. However, a normal season i n the Minnedosa area i s unusual and was not experienced during t h i s study.  In a l l three years the f i r s t and main f l i g h t s  of mallards arrived at approximately the same time, March 28-30 and A p r i l 15-20, but the a r r i v a l of spring was e n t i r e l y d i f f e r e n t . occurred i n 1957;  An early spring  the ponds were open and stayed open before the main f l i g h t  of mallards arrived.  In 1958  the ponds opened early but became completely ice  covered at the end of A p r i l during almost a week of b l i z z a r d conditions and near zero temperatures.  In 1959  the water areas were slow to open and were  not e n t i r e l y free of i c e u n t i l the end of A p r i l . By the time the mallards reached the Minnedosa region most of them were i n breeding p a i r s .  The b i r d s arrived as small mixed flocks of mallards and  p i n t a i l s (Anas acutaj and congregated, sometimes i n large concentrations, on the flooded or wet stubble f i e l d s .  The f l o c k s were well dispersed by the end  of A p r i l as the i n d i v i d u a l pairs established t h e i r home ranges and nesting territories.  - 31 -  The breeding home range was  described by Sowls (1955) as the area i n  which a b i r d spends i t s period of i s o l a t i o n between breakup of spring gregariousness and reformation of f a l l gregariousness.  In general t h i s was  true i n the Minnedosa area but there were periods of reversion to gregariousness such as when hens which l o s t their nests joined groups of loafing waterfowl between nesting attempts.  The males also, returned to a  gregarious behavior during the summer; as the hens began to incubate the males formed groups and l a t e r joined large concentrations of mixed waterfowl  on  moulting areas. The size of the home range of mallard pairs i s quite v a r i a b l e and i s u t i l i z e d by other waterfowl as w e l l as other mallard p a i r s .  The defended  portion of the home range, or nesting t e r r i t o r y , i s also variable; i t may include only a small area around a single pond or. an area almost equal to the home range.  U n t i l the pair bond i s broken both male and female l i v e and feed  within t h e i r home range.  The range of a pair of mallards i s generally smaller  than that of the drake alone; Dzubin (1955) described a home range of a p a i r of mallards on the Roseneath study area and showed that the area.covered by the drake alone was  i n excess of seven hundred acres, almost double that of  the p a i r . The grouped b i r d s , u n t i l t h e i r departure f o r the moulting ponds were not r e s t r i c t e d i n their movements over the study area.  Their f l i g h t patterns,  appeared to be random movements between feeding and l o a f i n g areas.  In 1959 an  unusual condition existed, more grouped b i r d s were noted than was the normal condition and the groups stayed on the study area well into the brood  season.  These b i r d s were similar to the early spring concentrations, i n that they . consisted of what appeared to be breeding pairs as well as males.  The  - 32 -  apparent breeding pairs i n the summer concentration were probably b i r d s that had moved into the area from the grasslands where more severe drought conditions existed. Thus there appeared to be two basic patterns of mallard f l i g h t behavior on the Minnedosa study area.  The movements of the breeding p a i r s were  r e s t r i c t e d t o t h e i r home range; within each pair there appeared to be a sexual difference i n the range of f l i g h t .  The males covered more t e r r i t o r y than did  the females and i n one case at least (Dzubin 1955 )• we know that the male's range of t r a v e l was  almost double that of the female.  The non breeding groups  of mallards on the other hand, appeared t o have more random f l i g h t patterns. They were not r e s t r i c t e d to a limited home range but t r a v e l l e d f r e e l y throughout the study area.  Broods - There i s a lack of information concerning the habits and of mallard broods.  requirements  They are known to t r a v e l long distances overland from  ponds which are drying up to ones which are more permanent.  Hochbaum (194A-)  c i t e s several instances of overland t r a v e l by mallard broods i n the Delta marsh of Manitoba and the procedure of constructing permanent brood waters by Ducks Unlimited i s based on the assumption broods w i l l t r a v e l two to three miles to reach permanent water.  Mallard broods are also known to t r a v e l  shorter distances between ponds, f o r no apparent reason.  Evans  (1951)  conducted a study of the movements of waterfowl broods on the Roseneath study area and made some interesting observations and conclusions. Evans determined that the average distance t r a v e l l e d by mallard broods was  0.013  miles per day and knew of no mallard brood which occupied a single  pothole for more than twenty days.  He found that the influence of the spacing  - 33 -  of potholes on brood mobility was quite marked.  Those broods which occupied  the region of high pond density were almost twice as mobile as those i n the low density region.  From Evans' data i t appears that the pattern of brood  movement and d i r e c t i o n i s completely random and since no motherless broods were known to move from pond to pond, overland t r a v e l i s i n i t i a t e d by the hen. Apparently overland journeys of mallard broods continue throughout the season.  The reasons f o r this continual t r a v e l are either random nomadic  movements or responses by the hen, to changes i n the environment.  The l a t t e r  i s probably the case since the young alone are not known to move.  The female,  aware of the conditions i n her home range, i s probably continually seeking better cover and food conditions i n which to rear her young.  I t makes one  wonder however, when a hen leads her brood from one pond to another that i s e s s e n t i a l l y similar i n cover type and abundance of food, what factor i n the environment has induced her to move.  Analysis of Gullet Contents Adult Mallards  . . .  For the determination of summer food of adult mallards, 211 available from b i r d s c o l l e c t e d from l a t e March to early August.  stomachs were However, only  9 6 , 50 males and 46 females, had s u f f i c i e n t food i n t h e i r g u l l e t s to be used i n the determinations. Although the adult mallards depended upon the plant kingdom for a large part of t h e i r summer d i e t , the majority of the* foods were derived from the animal kingdom.  In the 96 g u l l e t s examined, the food  consisted of 45.7% plant and-54.3% animal materials. by volume and mean proportion.  Table 12 l i s t s the foods  - 34 -  Table 12.  Volume and mean proportion of foods found i n the g u l l e t s of 96 adult mallards c o l l e c t e d i n the summer months of 1957. 1958 and 1959  Kind of food  PLANT FOODS  T o t a l volume (milliliters)  331.5  Or amineae Cyperaceae Lemnaceae Polygonaceae Chenopo d i ac e ae Ceratophyllaceae Rosaceae Leguminosae Haloragaceae Compo sitae ANIMAL FOODS Annelida Hirudinea Arthropoda Crustacea Arachnoidea Insecta Mollusca Gastropoda  Per cent volume  63.9  45-7 48.2 0.2 tr 0.1 14.7 tr tr tr tr tr  252.9 1.2 tr 0.7 76.4 0.1 0.1 tr 0.1 tr 36.1  187.1  Proportion of food  24.6 0.5 tr 0.1 . 20.0 tr 0.2 tr 0.1 tr 54.3  5.0  1.0  0.7  0.9 tr 179.5  0.2 tr 34.6  1.0 tr 51.4  1.7  0.3  1.2  Plant foods - The present study showed that less than one h a l f of the summer diet of adult mallards was derived from the plant kingdom. 45.7% ± 9.5% ( 0 . 0 5 l e v e l ) of the foods consumed.  Plants made up  They were found i n 59 o f the  96 g u l l e t s examined and varied i n volume from a trace to 4 9 . 0 m i l l i l i t e r s . A l l of the plant foods examined were i n the farm o f seeds with the exception of duckweeds (Lemna sp.), which appeared as traces of debris i n only f i v e gullets.  The i n d i v i d u a l pleats found i n the g u l l e t s are l i s t e d i n Appendix 5 .  Examination of Table 12 shows that the two most important sources of plant  - 35 -  foods were the Gramineae and Chenopodiaceae f a m i l i e s . represented by three main species, barley aestivum L.) and barnyard grass  The Gramineae family,  (Hordeum vulgare L . ) , wheat (Triticum  (Echinochloa c r u s g a l l i  (L.) Beauv.) contributed  over one h a l f (53.8%) of the plant foods and 24.6% of the summer d i e t . The other important family, Chenopodiaceae, represented by a single species, lamb's quarters  (Chenopodium album), supplied 43.8% of the plant foods and 2 0 . 0 % o f  the summer d i e t . In the two years, 1957 and 1959> that the sample of g u l l e t s was large enough f o r comparison (Table 1) there was a difference i n feeding habits. 1957. plant foods made up 3 3 . 7 % £ 13.6  In  ( 0 . 0 5 l e v e l ) of the d i e t whereas, i n  1959, they, made up 58.9% t 1 3 . 5 ( 0 . 0 5 l e v e l ) .  Application of Students' " t "  test to. these data indicate that the proportion of plants consumed i n 1957 and 1959 was s i g n i f i c a n t l y d i f f e r e n t . The calculated value of " t " was 2 . 6 2 as compared to I . 9 8 6 , the table value o f " t " at the 0 . 0 5 l e v e l . Table 13. l i s t s the plant foods examined i n g u l l e t s of 92 mallards c o l l e c t e d i n 1957 and 1959.  In 1958 only four f u l l g u l l e t s were available,  none of which contained plant foods.  The Gramineae family showed a pronounced  drop i n use from 1957 to 1959; i t provided 33.4% of the food i n 1957 and 19.5% i n 1959.  More important however, was the f a c t that the Gramineae supplied  99.1% of the plant foods i n 1957 and only 33.1% i n 1959. The plants of the waste areas, such as dry roadside ditches and pond edges, were the ones that received.the  increased use i n 1959.  Barnyard grass  (Echinochloa c r u s g a l l i )  increased i n use from 2.0% i n 1957 to 3 . 8 % i n 1 9 5 9 , while lamb's quarters (Chenopodium album) increased from only a trace i n 1957 to 37.8% i n 1959 and supplied 64.2% of the plant  foods.  - 36 -  Table 13.  Plant foods found i n the g u l l e t s of adult mallards c o l l e c t e d i n 1957 and I959 Proportion o f food  Plant food 1957  Gramineae Hordeum vulgare Tritieum aestivum Echinochloa c r u s g a l l i Other grasses • Ghenopodiaceae Chenopodium album  33.4  tr 0.3  TOTAL PLANTS  33.7 41  12.0 9.6 2.9 0.1  8.0 7-5 3.8 0.2  37-8  20.0  • 20.0  1.6  1.1  37.8  tr  Mean  24.6  19.5 12.6 18.8 2.0  Other plants  Number of g u l l e t s  1959  58.9 51  45-7 96  Animal foods - Animals were the major source of spring and summer foods of adult mallards i n the Minnedosa area. up 5 4 . 3 % ± 9.5%  They were found i n 71 g u l l e t s and made  ( 0 . 0 5 l e v e l ) of the foods consumed.  Appendix 6 l i s t s the  •  groups of animals, both by t o t a l volume and mean proportion, found i n the gullets.  The Class Insecta alone supplied more than one h a l f (51.4%) of the  t o t a l animal foods, whereas Annelida, Mollusca and Crustacea played only a minor role and supplied 2.9% of the t o t a l food and 5.3% of the animals.  The  order Diptera, represented mainly by l a r v a l stages of the family Tendipedidae, was the most important insect order and provided 24.6% of the d i e t of adult mallards.  Almost as important a source of food was the order Trichoptera  which supplied 17.8%  followed by Odonata (5.5%) and Coleoptera ( 3 . 3 % ) .  - 37 -  There was a decrease i n the proportion of animal foods consumed from  1957  66.3% ± 13.6% (0.05 l e v e l ) of the t o t a l foods was of animal o r i g i n while i n 1959, 41.1% ±13.5% (0.05 l e v e l ) of the foods were animal. The calculated value o f Students' " t " , 2.62, compared to the table value I.986 to  I959.  In  at the 0.05  1957,  l e v e l , indicates that the difference between the two years was  significant.  The proportions of animal foods consumed i n  are l i s t e d i n Table 14.  1957> 1958 and 1959  The data from 1958:are included i n the table but are  too few to use for comparison with the other two years.  Table 14.  Animal foods found i n the g u l l e t s of adult mallards c o l l e c t e d i n 1957, 1958 and 1959 Proportion of food  Animal food 1957 Hirudinsa Crustacea Insecta Odonata Hemiptera Trichoptera Coleoptera Diptera Gastropoda TOTAL ANIMALS  Number of g u l l e t s  0.9 63.7  9.6 0.2 17.9 2.7 33.3 1.7  1958  16.6 12.5 73.4  9.3  1959  Mean  0.3 0.1 39.8  17.9 12.5 33.7  0.1 0.1 19.6 3.1 16.9 0.9  0.7 1.0 51.4 5.5 0.2 17.8 3-3 24.6 1.2  66.3  100.0  41.1  54.3  41  4  51  96  Like other animal foods the Class Insecta showed a marked decrease i n use from  1957  to  1959;  i t provided  63.7%  of the food i n  1957  and  39.8%  in  I959.  However, the r e l a t i v e use of Insecta remained almost the same; the c l a s s made  - 38 -  up 96.1% of the animals i n 1957 and 96.8% i n 1959.  Not a l l insect orders were  affected to the same degree, some increased i n importance while others declined.  Odonata showed the most marked decrease from supplying 9.6% of a l l  foods and 14.5% of the insects i n 1957 to 0.1% and 0.2% i n 1959-  The Biptera  also declined to almost one half from 33*3% to 16.9% but s t i l l provided a large share of the insect material; Diptera provided 50.2% of animal materials i n 1957 and 41.1% i n 1959.  Trichoptera and Coleoptera showed a s l i g h t  increase i n use from 17.9% and 2.7% i n 1957 to 19.6% and 3.1% i n 1959. However, both almost doubled i n value as animal foods:  Trichoptera supplied  only 27.0% of the animal foods i n 1957 as compared t o 47.7% i n 1959 and Coleoptera increased from 4.1% to 7-5%.  Table 15 shows the chaiges which  occurred i n the animal foods from 1957 to 1958.  Table 15.  Per cent composition of the animal foods found i n adult mallards i n 1957 and 1959 Per cent composition  Animal  1957 Hirudinea Crustacea Insecta Odonata Hemiptera Trichoptera Coleoptera Diptera Gastropoda  0.7 0.2 96.8  1-3  -96.I  2.6  1959  14.5 0.3 27.0 4.1 50.2  2.2  0.2 0.2 47.7 7-5 41.1  Sexual difference i n g u l l e t contents - Examination of g u l l e t contents showed  - 39 -  an apparent difference in the foods consumed by male and female mallards. Males consumed 54.1%  plant and 45.9%  animal foods with confidence l i m i t s of  £13.2% (0.05 l e v e l ) , whereas, females consumed 36.5% plant and 63.5% animal foods with confidence l i m i t s of - 13-5%  (0.05  applied to the data indicated that at the 0.10  level).  Students' " t " test  l e v e l of confidence a  s i g n i f i c a n t difference existed between the g u l l e t contents of males and females.  The calculated value of " t " for both plants and animals, was  compared to the table value of  I.84  1.66 at 0.10 l e v e l (Snedecor, 1956). Table 16  summarizes the proportion and composition of foods found i n the g u l l e t s of 50 males and 46 females c o l l e c t e d i n 1957,  Table 16.  1958  and  1959.  Proportion and per cent composition o f major foods found i n the g u l l e t s of 50 male and 46 female mallards c o l l e c t e d i n 1957, 1958 and 1959 Proportion of food  Per cent composition of food  Foods  :  Male TOTAL PLANTS Gramineae Cyperaceae Chenopodiaceae Other plants  54.1  TOTAL ANIMALS Insecta Other animals  45.9  35-0  Female  36.5  0.1 18.7  0.3  43-5 2.4  63.5  Male  100  100 0.2  34.6 0.5 160  100  3.5  36.7 2.5 59/2 1.6  64.7  13.4 0.9 21.6 0.6 60.O  Female  94.8 5.2  .  94.5 5.5  Table 16 shows an interesting comparison of the r o l e played by the plants normally found i n c u l t i v a t e d f i e l d s with those found i n the waste or wet  - 40 -  areas.  There was almost a complete reversal o f the r e l a t i v e importance of  Gramineae, Ghenopodiaceae and Cyperaceae i n the diets of male and female mallards. , In the male, 64.7% of the plants consumed were from the Gramineae and 34.8% from the Chenopodiaceae and Cyperaceae f a m i l i e s , whereas i n the female, 36.% of the plants were from the Gramineae and 61.7% from the Chenopodiaceae and Cyperaceae f a m i l i e s .  In the animal foods the r e l a t i v e  importance o f the groups was about the same for male and female mallards.  Juvenile Mallards For the determination of the food of juvenile mallards, 135 stomachs were available, of which 62 contained food materials i n the g u l l e t s .  A l l age  classes of young, from Class I to F l y i n g , (Gollop and Marshall, 1954) were c o l l e c t e d during the months of June, July and August.  Table 17 l i s t s , by age  c l a s s , the young mallards obtained for the study.  Table 1?.  Young mallards c o l l e c t e d f o r food habits studies during the summer months of 1957, 1958 and 1959  Number o f young mallards '•  Total  :  Age c l a s s I  II  III '  Flying  18  2?  1?  11  73  Gullets with some food  19  20  15  8  62  Total  37  47  32  19  135  Gullets empty  - 41 -  The young mallards showed a d i f f e r e n t pattern of feeding habits than that of the adults.  Whereas the adults consumed almost equal parts of plant and  animal foods during the summer, the young mallards depended upon the animal kingdom f o r the majority of t h e i r foods; plants accounted f o r 9.0% and animals 91.0% of the food.  Table 18 shows the volume a i d mean proportion of foods  found i n the g u l l e t s of young mallards.  Table 18. Volume and mean proportion o f foods found i n the g u l l e t s of 62 juvenile mallards c o l l e c t e d i n 1957, 1958 and 1959 Kind of food  PLANT FOODS  T o t a l volume (milliliters)  30.0  11.9  U n i d e n t i f i e d plants Sparganiaceae Zosteraceae Gramineae Cyperaceae Lemnaceae Polygonaceae Chenopodiaceae Leguminosae Haloragaceae Labi at ae NIMAL FOODS Bryozoa Plumatellidae Annelida Hirundinea Arthropoda Crustacea Arachnoidea Insecta Mollusca Gastropoda Chordata Pisces  Per cent volume  Proportion of food  9-0  0.5  0.2  0.4  0.3 15.8 12.4 0.5 0.1 0.1  0.1 6.3 4-9 0.2  0.9 2.7 4.7 0.1  tr  tr  tr tr tr  tr tr tr tr tr  tr  0.2 0.1  88.1  221.8  tr  0.1 tr  91.0  51.2  20.3  3-7  4.9  1.9  1.2  6.2 0.1 121.7  2.5  2.8  48.3  71.6  36.0  14.3  11.2  1.7  0.7  0.5  tr  tr  - U2 -  Plant foods - Plant parts, mainly seeds, made up 9 . 0 % ± 5 . 6 % ( 0 . 0 5 . L e v e l ) of the food of 6 2 juvenile mallards.  Examination of Table 18 shows that three  f a m i l i e s , Cyperaceae, Gramineae and Zosteraceae were the main contributors (92.2%)  of plant foods.  The proportions of individual plants found i n the  g u l l e t s of young mallards c o l l e c t e d i n 1 9 5 7 , 1 9 5 8 and 1 9 5 9 are presented i n Appendix J.  Table 1 9 .  Students' " t " values of plant and animal foods consumed by mallards i n 1 9 5 7 - 1 9 5 8 , 1 9 5 7 - 1 9 5 9 and 1 9 5 8 - 1 9 5 9 h  Calculated " t "  Year  juvenile  Table " t " ( 0 . 0 5 level)  1957-1958  2.05  45  .2.01  1957-1959  2.54  31  2.04  1.13  48  2.00  1958-1959  There was  a s i g n i f i c a n t change i n feeding habits during the study; the  young mallards ate progressively more animal and less plant foods from 1 9 5 7 to 1959.  Table 1 9 summarizes the Students' " t " test values f o r plant and animal  foods consumed.  The proportions of plant food eaten during each of the three  years are presented i n Table 2 0 .  The Cyperaceae family was the most important  contributor of plant foods; i t provided 6 3 . 6 % i n 1 9 5 8 and 4 1 . 7 % i n 1 9 5 9 .  46.8%  of the plant foods i n  The Gramineae was  1957»  important i n 1 9 5 7 when i t  supplied 4 5 . 1 % of the plant foods but i t decreased sharply to 1 0 . 6 % i n 1 9 5 8 and only a trace i n 1 9 5 9 .  Animal foods - The animal kingdom provided 9 1 . 0 % j: 5 . 6 % ( 0 . 0 5 l e v e l ) of the food of juvenile mallards.  Animal foods were found i n a l l but two of the 6 2  - 43 -  g u l l e t s examined.  The Class Insects was  the most important  food of young mallards; i t contributed 71.6%  single source of  of the food (Table 18).  important was the Gastropoda which contributed 11.2%  of the food.  Also  The  animal  groups which were found i n the g u l l e t s of juvenile mallards are summarized i n Appendix 8.  Table 20.  Proportion of plant foods found i n the g u l l e t s of 62 young mallards i n 1957, 1958 and 1959 Proportion of food  Plant  1957  1958  - 1959  Zosteraceae Gramineae Cyperaceae Other plants  10.6 11.0 1.9  1.5 0.7 4.2 0.2  0.3  TOTAL PLANTS  23.5  6.6  1.2  Confidence l i m i t s 0.05 l e v e l  19.9%  6.9%  2.1%  Number of g u l l e t s  14  31  17  0.5 0.4  A s i g n i f i c a n t increase occurred i n the use made of animal foods from to 1959  (Table 19).  Animals increased from 76.5%  of the diet i n 1959Table 21.  of the diet i n 1957  to  1957 98.8%  The actual changes that took place are summarized i n  This table shows the proportion of the major items of animal foods  consumed in.1957, 1958  and  1959.  Examination of Table 21 reveals there was  l i t t l e change i n the  composition of the animal foods i n the three years.  The Gastropoda probably  - 44 -  Table 21.  Proportion of animal foods found i n the g u l l e t s of 62 young mallards i n 1957, I958 and 1959  Proportion of food Animal  1957 Plumatellidae  1958  1959  7.4  Hirudinea  0.8  1.3  1.3  Crustacea  1.6  4-5  0.5 0.2  Arachnoidea 67.O  Insecta Unidentified Ephemeroptera Odonata Hemiptera Trichoptera Coleoptera Diptera Hymenoptera  0.6  63.2  0.3  8.2 1.6 21.3 4.6 27-5  0.5 25.3 2.9 36.8 0.6  Gastropoda  7.1  90.9  15.9  5.9  1.0  Pisces TOTAL,ANIMALS  76.5  Confidence l i m i t s 0.05 l e v e l  19.936  Number o f g u l l e t s  14  67.7%  98.8  93-4  2.1%  6.9%  17  31  varied the most, they supplied 9.3% of the animal foods i n 1957, and 6.0% i n 1959«  11.4 0.1 6.6 6.5 22.9 .8.9 33-9 0.6  17.0%  i n 1958  The Insecta showed a drop i n 1958 when i t contributed only  of the animal foods as compared t o 87.6% i n 1957  and 92.0% i n  however, i n a l l years, the Insecta was the major source of foods.  1959, A single  species from the Phyllum Bryozoa, Plumatella repens L., appears as a  - 45 -  r e l a t i v e l y important source of food, but since i t was found i n only three stomachs i n 1958, I do not think i t was an important food source.  Analysis o f Gizzard Contents The gizzard contents o f adult and young mallards could not be accurately measured; apparently, secretions i n the proventriculus soften and p a r t i a l l y prepare foods f o r digestion.  Seeds with a hard pericarp and insects with  s c l e r o t i z e d s k e l e t a l parts appeared to r e s i s t the softening process, whereas soft seeds and animals were p a r t i a l l y digested.  Since i t was impossible to  determine from insect remains, the actual number o f animals involved, estimates o f the proportions of animal foods consumed were not obtained. I n d i v i d u a l plants and animals i d e n t i f i e d i n gizzards of adult and young mallards are l i s t e d i n Appendices 9 and 10.  Adult Mallards Items o f food found i n 211 mallard gizzards examined are l i s t e d i n Table 22.  Examination of the table shows that hard seeds of t h e Cyperaceae,  Sparganiaceae  and Haloragaceae  they were found i n  f a m i l i e s , were the most common plant foods;  84.4%, 10.9% and 20.4% respectively, of the gizzards  examined and made up 30.5% of t o t a l occurrences.  Soft seeds of the Gramineae  and Chenopodiaceae families were found i n 34.6% and 20.4% of the gizzards and contributed 14»5% of the t o t a l occurrences. Animals with a hard covering or exoskeleton, appeared to be more important than soft bodied animals.  Insecta with s c l e r o t i z e d s k e l e t a l parts,  were e a s i l y recognized; Trichoptera appeared Diptera i n  in  47-4%, Coleoptera i n 41.?% and  37-9% of the gizzards and made up 33*5% of the t o t a l occurrences.  - 46 -  Table 22.  Occurrence o f foods found i n the gizzards of 211 adult mallards c o l l e c t e d during the summers of 1957, 1958 and 1959 Occurrence i n gizzards  Kind of food Number o f times used  TOTAL PLANTS Unidentified plants Sparganiaceae Zosteraceae Gramineae Cyperaceae Lemnaceae Liliaceae Polygonaceae Chenopodiaceae Cruciferae C aryophyllac e ae Cer ato phyllace ae Rosaceae Leguminosae Haloragaceae Hippuridaceae Umbelliferae Cornaceae Polemoniaceae Verbenaceae Labi at ae Plantaginaceae Caprifoliaceae }TAL ANIMALS Hirudinea Crustacea Arachnoidea Insecta Unidentified insects Ephemeroptera Odonata Hemiptera Trichoptera Coleoptera Diptera Gastropoda TOTAL OCCURRENCE  431  3 23 5 73 178 8 2 23 35 1 1 10 3 8 43 2 1 1 1 1 6 2 1  372  358  1 4 2  53 1 20 16 100 88 80  7 803  Per cent times used  53.7  0.4 2.9 0.6 9.1 22.2 1.0 0.2 2.9 4.4 0.1 0.1 1.2 0.4 1.0 5-4 0.2 0.1 0.1 0.1 0.1 0.7 0.2 0.1  46.3  45.0  0.1 0.5 0.2  6.6 0.1 2.5 2.0 12.5 11.0 10.0 0.9  Per cent of b i r d s  94.8  1.4 10.9 2.4 34.6 84.4 3.8 0.9 10.9 16.6 0.5 ...-0.5 4.7 1.4 3.8 20.4 0.9 0.5 0.5 0.5 0.5 2.8 0.9 0.5  85.8  0.5 1.9 0.9  85.8 25.1 0.5 9.5 7.6 47.4 41.7 37.9 3-3  - -47 -  Table 23.  Occurrence of foods found in the gizzards of 135 juvenile mallards collected in 1957, 1958 and 1959 Occurrence in gizzards  Kind of food  :  Number of times used TOTAL PLANTS Unidentified plants Sparganiaceae Zosteraceae Gramineae Cyperaceae Lemnaceae Polygonaceae Chenopodiaceae Cruc iferae Ceratophyllaceae Rosaceae Leguminosae Halorag aceae Umbe H i ferae Labiatae Compos itae  245  TOTAL ANIMALS Plumatellidae Hirudinea Crustacea Arachnoidea Insecta Unidentified insects Odonata Hemiptera Trichoptera Coleoptera Diptera Hymenoptera Gastropoda  297  TOTAL 0CCURR1NCE  274  542  1 13 16 21 110 4 10 5 2 8 2 3 34 2 13 1 2 2 4 2 43 9 32 70 58 61 1 13  Per cent times used 45-2  o.i 2.4 3.0 3.9 20.3 0.7 1.8 0.9 0.4  Per cent of birds 85.2 0.7 9.6 11.9 15.6 81,5  3.0 7-4 3.7 1.5 5.9 1.5 2.2 25.2 1.5 9-6 0.7  1.5  0.4 0.6 6.3 0.4 2.4 0.1 94.8  54.8  50.6  0.4 0.4 0.7 0.4 7.9 1.7 5.9 12.9 10.7 11.3 0.1 2.4  94.8  1.5 1.5 3.0 1.5 31.9 6.7 23.7 51.9 43.0 45.2 0.7 9.6  - 48 -  Soft bodied animals were rarely recognized and thus appeared to be r e l a t i v e l y unused by mallards.  Juvenile Mallards Gizzards from 135 juvenile mallards of a l l age classes were available for study.  The food items found are presented i n Table 23.  forms of Cyperaceae recorded.  Hard seeds of aquatic  and Haloragaceae were the most abundant plant foods  Cyperaceae were found i n 81.5% and Haloragaceae i n 25.2% of the  gizzards; both accounted for over one h a l f (44.9% and 13.9%) of the t o t a l plant occurrences.  Other aquatic plants such as members of the Zosteraceae,  Sparganiaceae and Gramineae were also well represented i n the gizzards examined. In animal foods, the Class Insecta was represented i n 94•8% of the gizzards and accounted f o r 50.6% of the t o t a l occurrence of food.  The insect  groups most commonly found, were the e a s i l y recognized Hemiptera, Trichoptera, Coleoptera and Diptera, a l l of which have s c l e r o t i z e d sketetal parts.  Soft  bodied animals represented only 4.2% of the gizzard food.  DISCUSSION  Feeding Behavior of Mallards Mallards belong to the subfamily Anatinae, which i s commonly referred to as dabbling or surface feeding ducks.  One of the c h a r a c t e r i s t i c s of this  group i s that they feed by tipping and dabbling along the edges of lakes, ponds and smaller bodies of water.  Kortright (1943) i n describing the  feeding habits of the Anatinae says:  "River and pond ducks, or surface  - 49 -  feeding ducks, feed, as their name implies, either at the surface, where they skim the water at the edges of the shores and banks, or by "tipping", t a i l up, in the shallow places, reaching down to obtain their sustenance from the bottom.  Many of the ducks of this subfamily graze on land as do  the geese, and some wander into the woods in search of nuts, berries and land insects." Methods used by mallards to obtain food are variable.  Not only do they  use the methods described by Kortright but also they dive for food, catch flying insects and strain water through their beak to take small organisms and plants.  The actual movements involved in securing foods are innate.and  are fully developed at the time of hatching (Weidmann, 195&). Weidmann (op. c i t . ) contends that the different ways of taking foods is activated by the degree of hunger, however, he points out that isolated movements such as idle straining of water and snapping at flying insects is independent of the feeding drive. The question arises whether selection of individual items of food is an innate behavior pattern or whether mallards learn to recognize food.  I  believe i t is probably a combination of both; I have seen newly hatched mallard ducklings feed on insects after leaving the nest on their way to water and Geyr von Schweppenburg (1959) reports two to three day old mallards actively feeding on ground barley.  In one case the ducklings displayed innate  behavior in taking insects and in the other case, an .ability to rapidly learn edible articles in their environment.  No doubt their knowledge of  which foods are edible is acquired on a t r i a l and error basis.  One must  assume that mallards pick their food by visual means but are they able to do this while feeding under water?  The ability of a duck to see under water  - 50 -  has never been demonstrated, therefore I would suspect that most underwater feeding i s a random, searching process. mallards can probably  Under good l i g h t and water conditions  see food items near the surface o r even on the bottom  and go after them, but under poor l i g h t and water conditions t h i s would not be possible.  Comparison o f Gullet and Gizzard Contents In determining  the food habits o f mallards, g u l l e t materials proved  superior to gizzard materials because the amount of animal foods found i n gizzards could not be accurately measured.  Koersveld  (1950)  i n studying the  food habits of jackdaws (Corvus monedula spermologus ( V i e i l l ) ) , found that digestion o f soft bodied animals was already f a r advanced i n b i r d s k i l l e d twenty minutes after feeding.  In b i r d s k i l l e d twenty minutes after taking  food but kept for three days before examining the stomach contents, found that soft bodied animals had completely  Koersveld  disappeared whereas the  s c l e r o t i z e d remains of insects were s t i l l v i s i b l e and c e r e a l grains were unaffected. During the spring and summer months, when mallards have access to Trichoptera larvae, another source o f error may be added t o gizzard analyses. Certain f a m i l i e s of Trichoptera, such as Limnephilidae, l a r v a l cases from a variety o f materials.  construct t h e i r  In the Minnedosa area many of the  cases were constructed almost e n t i r e l y of sedge seeds (Carex sp.).  Other  seeds were also used, as were empty s h e l l s of Mollusca, p a r t i c u l a r l y the family Planorbidae.  Plate VII i l l u s t r a t e s some of the types of l a r v a l cases  constructed by members o f the order Trichoptera.  L a r v a l cases are recognizable  i n the g u l l e t and i n the gizzard after a recent feeding, however, i n the  PLATE YII  Family Limnephilidae showing the variety of materials used i n the construction of l a r v a l cases, (magnification X2.2) 1.  case made o f d r i e d plant stems, mostly rushes  2.  case made o f duckweed (Lemna t r i s u l c a )  3.  case of duckweed and the s h e l l s o f snails  4.  (Gastropoda)  case of s n a i l s h e l l s , small clam s h e l l s (Pelecypoda) and duckweed  5.  case of s n a i l s , duckweed and seeds  6.  case made almost e n t i r e l y of sedge seeds (Garex sp.)  7.  case made almost e n t i r e l y of bulrush (Scirpus sp.) seeds  8.  case made of duckweed, the seeds of bur-reed (Sparganium sp.) and sedges  9.  case made of f i n e grains of sand  - 51 -  gizzard, l a r v a l cases from a previous feeding, may be reduced to their component parts.. The use of gizzards i n the study of waterfowl food habits i s an established procedure. Many waterfowl workers however, have questioned the method and have pointed out that gizzard analysis may exaggerate  the value  of c e r t a i n hard foods (Pirnie, 1935, and Cottam, 1939)• Surprisingly, t h i s did not r e s u l t i n a change of methods even by the ones who doubted them. A search of the l i t e r a t u r e reveals that i t was not u n t i l 1959 (Dillon, 1959) that an attempt was made to show and explain the difference between gizzard and g u l l e t analysis. D i l l o n (op. c i t . ) worked with the stomachs of mallards shot during the winter. The b i r d s were l i v i n g almost e n t i r e l y on plant materials, and D i l l o n was able to measure gizzard contents and compare them with g u l l e t contents. B r i e f l y , he found that gizzard analyses tend to give a low r a t i n g to e a s i l y digested r i c e f i e l d seeds i n favor of hard marsh seeds that persisted i n the gizzard. For example, Junglerice (Echinochloa colonum (L.) Link) made up 20.7% of the g u l l e t foods and only 11;0% of the gizzard foods. On the other hand, spike sedge (Eleocharis quadrangulata  (Michx.) R. & S.) was 0.2%  of the volume of g u l l e t contents as compared to 8.4% of the volume of the o  gizzard contents. In the present study volumes of food i n gizzards were not measured, the contents of gizzards and g u l l e t s are compared on the b a s i s of occurrence of various foods. Table 24 summarizes the occurrence of main foods found i n g u l l e t s and gizzards taken from the same mallards. Examination of Table 24 shows a discrepancy between g u l l e t and gizzard foods from the same b i r d s . In both adult and young mallards, plant foods  - 52 -  received a higher rating in gizzards than they did in gullets. Hard seeds of the marsh plants, Cyperaceae, Polygonaceae and Haloragaceae, appear to be more important than soft seeds of Gramineae and Chenopodiaceae, whereas, the reverse is true in gullet contents. The reason for the higher rating of seeds of aquatic plants is their tough pericarp; this enables the seeds to withstand the grinding action of the gizzard for a longer period of time than can the soft seeds. Although Cyperaceae appeared as only slightly more than 20.0% of  Table 24. Major plant and animal foods found in the gullets and gizzards of 96 adult and 62 young mallards collected in 1957, 1958 and 1959 Per cent times used Kind of food Adult Gullet PLANT FOOD  35.6  Gramineae Cyperaceae Polygonaceae Chenopodiaceae Haloragaceae Other plants ANIMAL FOOD  TOTAL OCCURRENCE  Gizzard 56.8  12.7 20.2 3.7 6.4 4.0  3.8  9.8  43.2 0.3  2.4 14.6  1.4 10.4 10.4 11.2 6.6 1.7 1.2  7.8  4.7 3.4 295  347  Gizzard  43.9 5-2  4.7 20.4 1.1 2.0 4.3 11.4  8.2  0.9 1.3 1.3 5.5 56.1  77.6  1.3  12.2 18.0  Gullet  22.4  12.5 7-5 2.7 7.5 1.6 64.4  Hirudinea Insecta Hemiptera Trichoptera Coleoptera Biptera Other Insecta Gastropoda Other animals  Young  3.0  0.4  10.8  7.1 13.7 11.4 13.7 2.7 5.1 2.0  15.1  8.2 19.8 7.8 8.6  4.3 232  255  - 53 -  the times used i n both adult and young, seeds of t h i s group were found i n 72.9% of the gizzards of adults and 83.9% of the gizzards of young. In the animal foods, soft bodied animals received a lower r a t i n g than d i d animals with a hard exoskeleton.  Sclerotized parts o f Coleoptera, Trichoptera  and Hemiptera were e a s i l y recognized i n gizzard debris, although i n many cases, they were not i d e n t i f i e d to order.  Seasonal V a r i a t i o n of Foods During early spring on the study area i t was common to find flocks of mallards feeding i n grain stubble f i e l d s , but as the breeding season progressed and pairs became established on nesting t e r r i t o r i e s , f i e l d feeding f l i g h t s diminished.  However, mallard pairs and l a t e r young b i r d s , continued  to venture from ponds and into surrounding upland cover i n the search f o r food.  With such a pattern of feeding, a great variety of foods may make up  the summer diet of mallards. L i t t l e information has been published on feeding habits of mallards while on the breeding grounds.  McAtee  (1918) examined 1725  gizzards, but o n l y 2 5  were from b i r d s obtained during summer and the r e s u l t s were not r e p o r t e d o n . Stoudt  (1944) systematically c o l l e c t e d  mallards f o r stomach analysis during  August and September and found that during the late summer period the food consisted of 96-5% plant materials. During other seasons o f the year, Anderson  (1959) found  that corn (Zea mays L;) was the p r i n c i p a l food of  mallards i n I l l i n o i s ; McAtee (op. c i t . ) considered sedges (Cyperaceae) and grasses (Gramineae) the most important; and Martin, et al."(1951) ranked' pondweeds (Potamogeton sp.) and bulrush (Scirpus sp.) top of the preferred foods i n the west.  The apparent difference i n preference of food by black  - 54 -  ducks (Anas rubripes Brewster) was explained by Mendall  (1949).  He stated  that many foods are important largely because they are abundant and e a s i l y obtained and not necessarily because black ducks exhibit a p a r t i c u l a r fondness f o r them.  I think t h i s i s equally true f o r mallards.  I believe that preference plays only, a minor role i n choice of foods; the main reason that a mallard used a p a r t i c u l a r food i s because i t i s r e a d i l y available.  A food, to be available to mallards, must be abundant, i t must be  located where b i r d s can use the food and i t must be within the normal t r a v e l range of the b i r d s .  From f i r s t a r r i v a l i n spring u n t i l the end of the summer  moult, mallards become increasingly more dependent upon ponds and pond edges f o r t h e i r food supply.  During this time, although they may  not be as abundant  as equally desirable foods i n a more distant l o c a t i o n , only those foods which are found i n , or close to water areas, are available.  In mid and late summer,  as young b i r d s learn to f l y and as adults regain t h e i r powers of f l i g h t  after  the summer moult, they are l e s s dependent upon ponds; they become very active f l y e r s , often t r a v e l l i n g many miles between marsh and feeding area.  Because  of t h i s increased m o b i l i t y , vast crops of seeds, both w i l d and domestic,  are  available to the b i r d s . Seasonal variations i n food habits appear to be due i n part to a decrease or an increase i n mobility of mallards. summer as i t was  A c e r t a i n food may be as abundant i n  i n spring, but because the range of t r a v e l of b i r d s i s  smaller, the food i s less available.  On the other hand, a food may be more  available to adult males than i t i s to adult females because the home range of the male i s larger than that of the female.  Within the pond i t s e l f , c e r t a i n  foods may be more available to one age c l a s s than to another; young b i r d s are limited to feeding i n very shallow areas or i n areas of vegetation, whereas,  - 55 -  adults can feed by tipping i n areas with water depth up to 18 inches ( P h i l l i p s , 1923, Olney, i 9 6 0 ) . During t h i s study the only plant foods that were available i n spring were cereal grains and-seeds which carried over the winter either on the plant or on the ground.  As the season progressed seeds became less available because  of germination and new growth of p l a i t s i n the understory.  Cereal grains were  available during most of the season, i n f i e l d s during spring and t o a lesser extent along roadsides during summer.  A l l plant foods became very abundant  again i n late summer as seed crops matured.  Animal foods, on the other hand,  increased i n abundance during spring and summer months and declined i n late summer (Figures 1, 2 and 3 ) . Seasonal variations of foods used by both adult and young mallards show a trend similar to changes i n a v a i l a b i l i t y of foods.  Figure-5 shows changes,  on a bi-weekly b a s i s , i n the proportion of plant and animal foods consumed during spring and summer months.  Foods consumed by both adult and young  mallards were used i n drawing the graph, however, most of the adult b i r d s were taken before June 15 and most of the young b i r d s a f t e r .  The data from which  t h i s figure i s drawn are summarized i n Appendix 11. When the f i r s t mallard stomach samples were taken i n the l a t t e r part of A p r i l , the foods consisted mainly of plant materials ( 6 7 . 4 % ) .  I t was during  t h i s period that seeds from the previous season were abundant and available, whereas the ponds had just become i c e free and bottom fauna were not numerous. As bottom organisms increased and seeds decreased i n abundance there was a change i n diet from predominantly plant to predominantly animal materials. The low i n plant u t i l i z a t i o n was reached i n the l a s t two weeks of July and showed signs of recovery i n early August as new crops of seeds began to  FIGURE  5.  CONSUMED  PROPORTION BY  ADULT  OF AND 1958  PLANT  AND  YOUNG AND  1959.  ANIMAL  MALLARDS,  FOODS 1957,  - 56 -  mature.  Had sampling of stomachs been c a r r i e d on during late August  and  September the complete change from an animal to a plant diet would probably have been demonstrated.  Undoubtedly,  as shown by other food studies, mallards  remain on a predominantly plant diet u n t i l they return to the breeding grounds i n the spring.  Comparison of goods of Adult and Young Mallards Because the majority of adult mallards were c o l l e c t e d before June 15, one would expect plant materials to be the important source o f food.  One would  also expect the food of adults to be different from the food of the ducklings c o l l e c t e d l a t e r i n the summer.  The data show t h i s t o be the case; 4.5.7$-9«5%  (0.05 l e v e l ) adult foods and 9.0% ± 5.6% (0.05 l e v e l ) of duckling foods were derived from the plant kingdom, Students' " t " test indicates a s i g n i f i c a n t difference (t= 5.71) at the 0.05  level.  When both adult and young mallards are c o l l e c t e d during the same period one would expect t h e i r food habits to be s i m i l a r .  However, Chura  (1961)  thought there was a difference i n that ducklings ate more animal foods than did females but by the time they were Class I I I , t h e i r food was s i m i l a r to that of adults.  I do not believe there was a difference i n proportions of  plant and animal foods used by adults and young i n late summer i n Minnedosa. The i n d i v i d u a l items that constitute the plant and animal foods may  be  d i f f e r e n t , due to a difference i n a b i l i t y to feed i n varying water depths, but the t o t a l foods should be the same.  The sample of adults taken i n late June  and July was not large enough to s t a t i s t i c a l l y compare with young, but the few samples taken tend to substantiate my b e l i e f .  The food of 7 adults c o l l e c t e d  from June 16 to August 15 consisted of 85.6% animal materials whereas, foods  - 57 -  of young taken from the same period were 90-3%  animal o r i g i n .  Food of Adult Mallards Annual Variations The data presented i n Tables. 6 and 7 show that the only s i g n i f i c a n t change i n o v e r a l l abundance of edge organisms occurred between 1958  and 1959•  However, because the majority of adult mallards were collected p r i o r to June 15, the abundance of edge organisms during t h i s period must be used f o r comparison;  these data are presented i n Table 25.  The comparison of foods  consumed by adults (Tables 13 and L4) with abundance of edge organisms (Table 25) is. i l l u s t r a t e d i n Figure 6.  Table 25.  Year  Edge fauna collected from.ponds during the period May 1 to June 15 i n 1957, 1958 and 1959 Organisms per square foot  Confidence limits  Sample size  0.05.level 187.1 126.3 24.5  1957 1958 1959  There was a s i g n i f i c a n t decrease organisms from 1957 in food habits.  to 1959,  98.0 51.7 6.9  14 31 19  (t=4-00) i n abundance of edge  but t h i s alone was not enough to cause the change  The r e l a t i v e a v a i l a b i l i t y of plant and animal materials,  played an important part i n determining the food selected. In the Minnedosa area, the most commonly grown crops were barley (Hordeum vulgare) and wheat (Triticum aestivum) both of which supplied the majority of plant foods i n  IS57  FIGURE OF PER  6.  ADULT  1958  COMPARISON MALLARDS  SQUARE  FOOT,  OF P L A N T AND NUMBER  IS59  AND ANIMAL O F EDGE  1957, 1958 A N D 1 9 5 9 .  FOODS FAUNA  - 58 -  1957-  The abundance of these grains d i d not change during the study but use  that was made of them decreased i n 1959-  At the beginning of drought  conditions i n 1958, many roadside ditches and shallow ponds went dry and created i d e a l seed beds; one of the main species to colonize these areas was the common weed, lamb's quarters (Chenopodium album).  In 1958, lamb•s  quarters was very common i n dried ditches and pond edges and under these i d e a l conditions produced a heavy crop of seeds.  With the temporary return of water  to ponds and ditches the following spring, lamb's quarters seeds were shed i n the water and were very numerous; i n some areas, they formed windrows along the shores.  Although they were probably not as abundant as cereal grains i n  stubble f i e l d s , they were more r e a d i l y available to b i r d s and received a higher use i n 1959 than did cereal grains. The r e l a t i v e a v a i l a b i l i t y of animal versus plant foods cannot be measured therefore one must assume that plants, p a r t i c u l a r l y lamb's quarters, were more readily available i n 1959 than were pond organisms which decreased i n numbers that year.  Even i f animals had not decreased, lamb's quarters would probably  have s t i l l been an important source of food because the seeds could be obtained by skimming the water surface without the necessity of dabbling or diving.  In 1957 on the other hand, f i e l d s with waste c e r e a l grains were the  major source of plant foods, however, because they were removed from ponds, plant foods received l e s s use than did pond animals. The r e l a t i v e a v a i l a b i l i t y of various pond organisms i s d i f f i c u l t to assess, however, i f underwater feeding i s a random process a v a i l a b i l i t y of bottom dwellers must be closely related to the abundance of them i n shallow waters.  A v a i l a b i l i t y of pond organisms l i v i n g i n association with vegetation,  either submergent or emergent, must also be closely r e l a t e d to abundance as  - 59 -  w e l l as to density of plant cover.  Although larvae of Trichoptera were more  abundant i n center samples than they were i n edge samples, they were found along the edge of the emergent vegetation zone or just outside the area used i n edge sampling.  Trichoptera increased i n center samples from 1957 to 1959  and with the decrease i n water l e v e l s , i t i s possible that they were available i n 1959 to mallards feeding by dabbling and diving.  The increased use that  was made of Trichoptera i n 1959 indicates that t h i s was the case.  Odonata  nymphs, which l i v e i n close association with vegetation decreased both i n abundance and i n value as a food source i n 1959'  Other pond organisms showed  l i t t l e change i n use from 1957 to 1959 (Table 15).  Sexual Differences Foods u t i l i z e d by adult male and female mallards were s i g n i f i c a n t l y d i f f e r e n t at the 0.10 l e v e l of p r o b a b i l i t y  (t =1.84); males consumed a higher  proportion o f plant foods (54;1%) than did females (36.5%)-  Examination of  Table 16 shows the majority of plant foods consumed by females were those usually associated with water and waste areas; the Chenopodiaceae and Cyperaceae f a m i l i e s made up 61.7% o f the plant foods.  Of plant foods u t i l i z e d  by males, 64.7% were obtained from the Gramineae family found i n c u l t i v a t e d fields.  Another comparison that can be made i s between u t i l i z a t i o n of both  plant and animal foods found i n or near ponds and u t i l i z a t i o n of e s s e n t i a l l y f i e l d foods.  Female mallards obtained 86.6% of t h e i r food from ponds or pond  edges and 13«4% from f i e l d s , whereas, males obtained only 64.Tfo of t h e i r food from ponds and 35.3% from f i e l d s . ' There was a difference i n feeding habits of adult male and female mallards during the breeding and nesting seasons.  Males were extremely mobile  - 6o -  over a large home range where a wide variety o f foods were available.  On the  other hand, females were less mobile; their main feeding a c t i v i t i e s were r e s t r i c t e d to a few water areas within a small home range where the variety of available foods was limited.  Food of Juvenile Mallards Age Differences A recent study of food habits of mallards was made by Ghura (1961) i n the Bear River Migratory B i r d Refuge i n Utah.  He conducted an extensive research  program designed to determine a v a i l a b i l i t y and preferences of food of juvenile mallards.  L i t t l e other detailed information i s available i n the l i t e r a t u r e ;  unfortunately, most food habits research has been of a very general nature. Chura (op. c i t . ) found a marked change i n feeding habits from Class I to Class III ducklings.  He states that Class l a ducklings consumed animal foods  almost e x c l u s i v e l y ; 90% animal foods were consumed by lb and 75% by I c . He considered Class I I ducklings t o be at the "threshold of maturity".  At this  stage Class I l a consumed 50% animal foods; l i b , 30% and l i e , 11% animal foods. The change over i n diet was complete i n Class I I I where the diet was less than 1% animal m a t e r i a l .  Of equal i n t e r e s t i s the fact that almost a l l animals  consumed by Glass I young were t e r r e s t r i a l insects, whereas, almost a l l animals used by Class I I were aquatic forms.  He states that "this rather  instantaneous switch-to aquatic forms may be caused by a.sudden maturing i n feeding behavior involving the head submersion and tip-up feeding of the adults".  Chura contends that the change from animal diet at hatching to plant  diet at maturity i s d i r e c t l y correlated with age and r e l a t e d body  requirements.  The proportions of animal foods consumed by juvenile mallards on the  - 61 -  Minnedosa study area are shown i n Table 26. 94.0% ±4.3% foods.  Examination of the table shows  (0.05 l e v e l ) of the diet of f l i g h t l e s s ducklings was  animal  Chi square value of O.57 with 2 degrees of freedom, indicates there  was no s i g n i f i c a n t difference i n the diets of the three age classes of non f l y i n g young.  There was however, a s i g n i f i c a n t difference (t = 2.75) i n the  proportion of animals i n the diets of non f l y i n g and f l y i n g young.  The food  of f l y i n g young consisted of 71.1% i 36.5% (0.05 l e v e l ) animals and 28.9% 36.5% plants.  Table 26.  Proportion of animal foods consumed by young mallards i n 1957, 1958 and 1959 Proportion of animal foods  Confidence limits 0.05 l e v e l  I II III T o t a l non flying  98.8 89-4 93.9  2.5 10.8 5.5  94.0  4.3  54  Flying  71.1  36.5  8  Age c l a s s  Sample size  19 20 15 .  With f l y i n g young, one would expect a s h i f t i n diet from animal to plant foods.  Young mallards with t h e i r newly acquired powers of f l i g h t , are  extremely mobile and are not l i m i t e d to a home range as were the adults during the breeding season.  The small sample of f l y i n g young obtained f o r this study  were c o l l e c t e d i n early August and did not exhibit the complete change over to a plant d i e t .  Pond fauna were s t i l l the most abundant source of food; aquatic  and f i e l d plants were beginning to reach maturity and harvesting of early  - 62 -  c e r e a l grains was just s t a r t i n g .  An adequate sample o f b i r d s taken i n late  August would probably have revealed they were l i v i n g almost exclusively on farmers*  crops.  I believe that the difference i n food habits of Bear River ducklings (Ghura, op. c i t . ) and Minnedosa ducklings was due t o a difference i n r e l a t i v e a v a i l a b i l i t y o f plant and animal foods.  Chura admits that although many  d i f f e r e n t v a r i e t i e s of p o t e n t i a l foods were present i n the marsh, few were abundant, whereas, the Minnedosa ponds produced large crops of fauna.  The  almost exclusive use of t e r r e s t r i a l fauna by Class I mallards on the Bear River marshes indicates a paucity o f available aquatic organisms.  The fact  that Geyr von Schweppenburg (1959) reported two to three day old mallards a c t i v e l y feeding on ground barley f u r t h e r suggests that young mallards are able to survive on many types of food, tbs main consideration being an abundant supply, regardless of source.  Annual Variations In the section dealing w i t h faunal c h a r a c t e r i s t i c s of ponds, only o v e r a l l annual changes i n abundance of center and edge organisms were considered. However, since the majority of mallard ducklings obtained f o r study were c o l l e c t e d between June 16 and August 15 edge fauna sampled during this period must be considered separately.  Table 27 shows tbs abundance o f edge fauna  during the period June 16 to August 15 i n 1957, 1958 and 1959.  The comparison  of foods consumed by young (Tables 20 and 21) with abundance o f edge fauna (Table 2?) i s i l l u s t r a t e d i n Figure 7. Examination of Figure 7 shows that there was no s i g n i f i c a n t difference i n abundance of bottom fauna between 1957 and 1959 but there was a s i g n i f i c a n t increase (t — I . 6 7 ) i n 1958.  The use  1957  FIGURE OF PER  7.  1958  COMPARISON  YOUNG SQUARE  MALLARDS FOOT,  OF AND 1957,  1959  PLANT  AND  NUMBER 1958  AND  ANIMAL OF  EDGE  1959.  FOODS FAUNA  Table 27. Edge fauna c o l l e c t e d from ponds during the period June 16 to August .15 i n 1957, 1958 and 1959  Year  Organisms per square foot  Confidence limits 0.05 l e v e l  Sample size  1957 1958 1959  195.5 377.2 205.5  69.7 168.2 109. A  29 45 24  that was made of bottom fauna by ducklings increased s i g n i f i c a n t l y from 1957 to 1958 ( t - 2 . 0 5 ) and from 1957 to 1959 ( t = 2 . 5 4 ) . In 1957, when water levels i n the ponds were high, emergent vegetation was abundant along the shallow edges.  Early maturing plants such as whitetop  grass (Scolochloa festucacea), sedges (Carex sp.) and spikerush (Sleocharis p a l u s t r i s (L.) H. & S.) were u t i l i z e d as a food source.  With the onset of  drought conditions i n 1958, emergent vegetation began to decline and by the brood season of 1959 was almost non-existent.  Although there was very l i t t l e  change i n abundance of pond fauna between 1957 and 1959, the r e l a t i v e a v a i l a b i l i t y o f the bottom organisms increased as emergent and shoreline vegetation died out.  Thus the importance of plant foods decreased as young  changed to an almost exclusive animal d i e t . The importance of animal foods increased during the study but the change could not be attributed to a s p e c i f i c animal.  Gastropoda showed the greatest  change i n use; they supplied 9*3$ of the animal foods i n 1957, 17.0% i n 1958 and 6.0% i n 1959.  Hemiptera and Odonata decreased i n bottom samples (Table 8)  but increased i n use from 1957 to 1959 (Table 21), a change which was probably brought about by an increase i n a v a i l a b i l i t y as the water levels receded.  The  -  64  -  change i n abundance and a v a i l a b i l i t y of Coleoptera was r e f l e c t e d i n t h e i r increased use as a food source.  Triehoptera and Diptera decreased both i n the  ponds and i n u t i l i z a t i o n by mallard ducklings.  Relationship of Food Use to A v a i l a b i l i t y A v a i l a b i l i t y of various foods i s d i f f i c u l t to assess because so many factors must be considered.  As was pointed out i n previous sections, food  a v a i l a b i l i t y i s a r e l a t i v e f a c t o r dependent upon many conditions; i t i s determined by abundance o f the food, location on, land or-in'water, mobility of 1  the b i r d s and-proximity  of other food sources.  Other f a c t o r s , such as the  stage of development of the food, organism and density of the cover i n which the food is" found, must also be considered. • Any single factor or combination of factors plays an important r o l e i n determining u t i l i z a t i o n of a food source; r e l a t i v e a v a i l a b i l i t y of a food i s not f i x e d , i t v a r i e s from area to area and from season to season.  For  instance, lamb's quarters (Chenopodium album) was more available i n 1 9 5 9 than i n the previous two years'because  i t was more abundant i n the ponds.  quarters had a higher use by females than d i d the more -distant f i e l d whereas, i n the case of the more mobile male, the reverse was  Lamb's seeds,  true. .  H y a l e l l a azteea (Amphiopoda) comprising 4 0 . 1 % of the edge fauna (Table 8) was  almost unused by mallards, supplying only 3 . 1 % of the animal diet of young  (Table 18) and 1.8% of adults (Table 1 4 ) •  H y a l e l l a was r e l a t i v e l y safe from  feeding ducks because of the protection afforded them by the dense beds of filamentous green algae i n the Minnedosa ponds.  Hemiptera and Coleoptera were  not as'abundant as the amphiopod but received more use because t h e i r habitat was not as dense and did not provide the same protective cover.  In ponds with  - 65 -  dense algae beds, Hemiptera and Coleoptera frequented the edges whereas, H y a l e l l a was most abundant within the beds. The stage of development of c e r t a i n organisms played an important part i n determining their r e l a t i v e a v a i l a b i l i t y .  Larval stages of Tendipedidae, which  inhabited the deep areas of the. ponds, were not as available to young mallards as they were to adults, but the pupae, as they came to the surface, were equally available.  I t was common to see ducklings a c t i v e l y skimming the  surface o f ponds feeding on pupae during a Tendipedidae hatch.  Most of the  Tendipedidae found i n the g u l l e t s of young were pupae whereas, larvae predominated i n the adults; unfortunately, adult stomachs were not taken at t h i s period f o r comparison. Data c o l l e c t e d i n the Minnedosa study area and i n other parts o f the mallard range, show that the feeding habits o f mallards are v a r i a b l e .  The  u t i l i z a t i o n of a food or group of foods appears to be determined by i t s relative availability.  CONCLUSIONS  1.  Emergent and pond shoreline vegetation was almost eliminated by the  change i n water levels from f l o o d conditions i n 1 9 5 7 to drought conditions i n  1959. 2.  A v a i l a b i l i t y of seeds during spring and summer i s dependent upon the date  of maturity of the seeds, the time o f the year they are shed and the understory on which they f a l l .  A v a i l a b i l i t y decreases i n spring as  germination and plant growth takes place and increases i n late summer as new crops of seeds mature.  - 66 -  3.  There was no s i g n i f i c a n t annual change i n abundance of bottom fauna  during the study but there was a general seasonal increase i n the spring u n t i l a peak was reached i n May, this was followed by a s l i g h t depression and another increase to a much higher peak of abundance i n mid August. 4.  Gizzard analysis i s not a r e l i a b l e method of determining mallard food  habits; i n i t i a l digestion i n the proventriculus and subsequent grinding action of the gizzard renders soft foods unrecognizable. 5.  Animals, p a r t i c u l a r l y aquatic insects, were the most important source of  the spring and summer foods of mallards i n the Minnedosa area.  Animals  contributed 54-3% of the food of adults and 91.0% of the food of ducklings. 6.  The food habits o f mallards changed during the spring and summer season  due to a change i n the r e l a t i v e a v a i l a b i l i t y of the plant and animal foods. Plant foods decreased and animal foods increased i n abundance during the season.  7.  There was a s i g n i f i c a n t change i n the diet of adult and young mallards  from 1957 to 1959.  U t i l i z a t i o n of animal foods by adults decreased from 66.3%  of the diet i n 1957 to 41.1% i n 1959-  Animal foods consumed by young mallards  increased from 76.5% i n 1957 to 98.8% i n 1959.  8.  There was a s i g n i f i c a n t difference i n the food of breeding and nesting  adults and the food o f ducklings; the majority of adult b i r d s were c o l l e c t e d prior to June 15 whereas, the majority of ducklings were c o l l e c t e d  after t h i s  date.  9.  During the breeding and nesting seasons, there was a s i g n i f i c a n t  - 67 -  difference i n the proportion of plant and animal foods consumed hy male and female mallards. The males t r a v e l l e d f r e e l y over a large home range where a wide variety of foods were available.  The females were less mobile; t h e i r  feeding was r e s t r i c t e d to a small home range where the v a r i e t y of available foods was l i m i t e d .  10.  There was no s i g n i f i c a n t difference i n foods consumed by the three age  classes of non f l y i n g ducklings but there was a difference i n the foods of non f l y i n g and f l y i n g young.  When juvenile mallards learn t o f l y they are more  mobile and have a wider variety o f foods from which to choose. 11.  U t i l i z a t i o n of plant and animal foods appears to be determined by  abundance and location of the food source i n the environment, the proximity of other foods, stage of development  of the food organism, density of cover i n  which a food i s found and by the mobility of the b i r d using the food.  12.  The r e l a t i v e proportions of plant and animal foods consumed by waterfowl  may not be of primary importance; mallards appear to be able to balance their d i e t s with many d i f f e r e n t kinds of food.  - 68 -  LITERATURE CITED  A l l e e , W. C , A. E . Emerson, 0 . Park, T. Park and K. P. Schmidt. 1949P r i n c i p l e s of animal ecology. W. B. Saunders Co., Philadelphia. 837 P« American Ornithologists' Union. 1957- Check-list o f North American b i r d s . American Ornithologists' Union. 5th ed. 691 p. Anderson, H. G. 1959- Food habits of migratory ducks i n I l l i n o i s . H i s t . Surv. B u l l . 27(4):287-344Bent, A. C. 1923. L i f e h i s t o r i e s o f North American w i l d fowl. Mus. B u l l . 126.  111. Nat.  U.S. N a t l .  B i r d , R. D. 1930. B i o t i c communities of the aspen parkland of c e n t r a l Canada. E c o l . 11:356-443. Chura, N. J . 1961. Food a v a i l a b i l i t y and preferences of juvenile mallards. Trans. 26th N. Am. W i l d l . Conf. 121-134Cochran, William G. 1956. Design and analysis of sampling, p. 489-523. In G. W. Snedecor, S t a t i s t i c a l methods. 5th ed. Iowa State College Press, Ames, Iowa. Comstock, John H. 1950. An introduction t o entomology. Comstock Publishing Co., Inc., New York. 1064p.  9 t h ed. rev.  Gottam, Clarence. 1939. Food habits o f North American diving ducks. U.S. Dept. Agr., Tech. B u l l . 643. 139 p. Cram, B. M. 1956. Waterfowl populations and production on the Roseneath study area, Southern Manitoba, 1956. Can. W i l d l . Serv. Mimeo. 5 p. Dasmann, William P. 1951. Game 3 7 ( l ) : 4 3 - 5 2 . Day, A l b e r t M. New York.  Some deer range survey methods.  1949. North American waterfowl. 329 P-  C a l i f . F i s h and  Stackpole and Heck, Inc.,  D i l l o n , Olan W., J r . 1959. Pood habits o f w i l d mallard ducks i n three Louisiana parishes. Trans. 24th N. Am. W i l d l . Conf. 374-382. Dobie, John. 1958. Personal correspondence. Apr. 5 t h , 1958.  Minnesota Dept. Conserv.  Dzubin, Alexander. 1954. The intensive study of waterfowl populations on a small block of a g r i c u l t u r a l land, Minnedosa, Manitoba. M.A. Thesis. Univ. B r i t i s h Columbia, A p r i l , 1954.  - 69 -  Dzubin, Alexander. 1955. Some evidences of home range i n waterfowl. Trans. 20th N. Am. W i l d l . Conf. 278-298. E l l i s , J . H. 1938. The s o i l s of Manitoba. Winnipeg, Manitoba.  Manitoba Economic Survey Board,  Evans, Charles D. 1951. A study of the movements of waterfowl broods i n Manitoba. M. Sc. Thesis, Univ. Minnesota, A p r i l , 1951. Evans, Charles D. 1955. Waterfowl breeding ground survey i n southern Manitoba, 1955. p. 77-88. Waterfowl populations and breeding conditions, summer 1955. USDI and Can. W i l d l . Serv., Spec. S c i . Rep., W i l d l . No. 3 0 . Evans, Charles D. 1958. Mimeo.  1959. Progress report, Breeding ground surveys i n Manitoba, 37 p. U.S. Dept. o f the I n t e r i o r , 1959.  Evans, Charles D. i 9 6 0 . Progress report, Breeding ground surveys i n Manitoba, 1959. Mimeo. 54 p. tr.S. Dept. of the I n t e r i o r , i 9 6 0 . Fernald, M e r r i t t L. 1950. Gray's manual o f botany. Co., New York. 1632 p. Geyr von Schweppenburg, H. Frhr. 1959. J . O r n i t h o l . 100 (4):497-403  8 t h ed. American Book  On the behaviour of the mallard.  Gollop, J . B. and W. H. Marshall. 1954. A guide f o r aging duck broods i n the f i e l d . M i s s i s s i p p i Flyway Council Tech. Section. 14 p. Hanson, R. C. 1957. Progress report, Waterfowl breeding ground a e r i a l surveys i n Southern Manitoba, 1956. Mimeo. 25 p., U.S. Dept. of the I n t e r i o r , 1957. Hanson, R. C. 1958. Progress report, Waterfowl breeding ground a e r i a l surveys i n Southern Manitoba, 1957. Mimeo. 20 p., U.S. Dept. of the I n t e r i o r , 1958. Henderson, I . F. and J . H. Henderson. 1939. A dictionary of s c i e n t i f i c terms. 3rd ed. Oliver and Boyd, Edinburgh. 383 p. Hochbaum, H. A. 1944. The canvasback on a p r a i r i e marsh. Inst., Washington, D.C. 201 p.  The Am. W i l d l .  Holm, E a r l R. and M. L. Scott. 1954. Studies on the n u t r i t i o n of wild waterfowl. N.Y. F i s h and Game J . 1(2):171-187Koersveld, E . van. 1950. D i f f i c u l t i e s i n stomach analysis. Ornith. Congr., Uppsala, June, 1950.  Xth Intern.  Eortright, F. H. 1943. The ducks, geese and swans of North America. The Am. W i l d l . Inst., Washington, D.C. 473 p.  - 70 -  Mabbot, Douglas C. 1920. Food habits of seven species of American shoalwater ducks. U.S. Dept. Agr., B u l l . 862. 67 p. Martin, A. G. and F. M. Uhler. 1939Pood of game ducks i n the United States and Canada. U. S. Dept. Agr., Tech. B u l l . 634. 157 p. Martin, A. C , H. S. Zim and A. L. Nelson. 1951. American w i l d l i f e and plants. McGraw-Hill Book Co., Inc., New York. 500 p. McAtee, W. L. 1918. Food habits of the mallard ducks of the United States. U.S. Dept. Agr., B u l l . 720. 36 p. ffiendall, Howard L. 1949. Food habits i n r e l a t i o n to black duck management i n Maine. J . W i l d l . Mgmt. 13(1):64-101. M i s s i s s i p p i Flyway Council. 1958. management. March, 1958.  A guide to M i s s i s s i p p i Flyway waterfowl  Moyle, J . B. 1961. Aquatic invertebrates as related to l a r g e r aquatic plants and waterfowl. Minnesota Dept. of Conservation. Investigational report No. 233. Mimeo. 24 p. Olney, P. J . S. i 9 6 0 . Lead poisoning i n wildfowl, Part I I . B u l l . B r i t . Ornith. Club 80(3):53-59 Pennak, Robert W. 1953. Fresh-water invertebrates of the United States. Ronald Press Co., New York. 769 p. P h i l l i p s , J . C. 1923. A n a t u r a l history of the ducks, p. 21. M i f f l i n Co., Boston. V o l . I I . P i r n i e , Miles D. 1935. Michigan waterfowl management. Lansing, Mich. 328 p. Snedecor, George W. 1956. S t a t i s t i c a l methods. Press, Ames, Iowa. 534 p.  5th ed.  The  Houghton  Mich. Dept. Cons., Iowa State College  Sowls, Lyle K. 1955P r a i r i e ducks. The Staekpole Co., Harrisburg, Pa. W i l d l . Mgmt. Inst., Washington, D.C. 193 p.  and  Stoudt, Jerome H. 1944. Food preferences of mallards on the Chippewa National Forest, Minnesota. J . W i l d l . Mgmt. 8(2):100-112. United States Department of the I n t e r i o r . 1951. 1951 Status report of waterfowl. F i s h and W i l d l i f e Service, Washington. 39 p. United States Department of the I n t e r i o r . 1956. National survey of f i s h i n g and hunting. 1955. F i s h and W i l d l i f e Service C i r c . 44.  -  71 -  United States Department of the I n t e r i o r . . 1959. 1959 Status report o f waterfowl. USDI Spec. S c i . Rep., W i l d l . No. U5- Washington. United States Department of the I n t e r i o r . 1960a. Waterfowl status report, I960. USDI Spec. S c i . Rep., W i l d l . No. 5 1 . Washington. United States Department of the I n t e r i o r . 1960b. Waterfowl harvest i n the United States I959-I96O hunting season. USDI Spec. S c i . Rep. No. 5 2 . Washington. Weaver, John E . and, Frederic E . Clements. Book Co., Inc., New York. 601 p.  1938.  Plant ecology.  Weidmann, U l i . 1956. Verhaltangsstudien an der Stockente. Aktionssystem. Zeitschr. Tierpsych. 13(2):208-268.  1.  McGraw-Hill Das  - 72 -  Appendix 1.  Bi-weekly changes i n the number o f organisms per square foot sample found i n the centers of ponds studied i n 1957, 1958 and 1959 Center samples  Date 1957  Number of organisms  1958  1959  Number Sample size  of  organisms  Sample size  Number of organisms  Sample size -•- •  May  1-15 16-31  June  1-15  408.6  7 10 12 8  193.4  9  435.9  7  656.5  July  1-15  299.5 178.3 229.2  Aug.  16-31 1-15  392.4 178.9  16-30  Appendix 2 .  8  95.0 314.8  228.7 276.1  13 10 11 11  168.4 173.7 435-2 558.6  8 11  15 8  820.6  7  9 8  Bi-weekly changes i n. the number of organisms per square foot sample found i n the edges of ponds studied i n 1 9 5 7 , 1958 and 1959  Edge samples T\  O^A — 1958  1957  Number of organisms  May June  1-15 16-31  1-15 16-30  Sample size  133.6 143.0  13 10 11 11  8  250.7 132.2 448.2  6  754.6  167.1 117.7  8  168.5  Aug.  16-31 1-15  245.8 272.2  Sample size  8  6  1-15  1959  93.5  213.8  July  Number of organisms  9 6  15 8  Number of organisms  Sample size  21.0 27.2 101.8  8 11  616.5 I46.O  8  9 7  - 73 -  Appendix 3.  Bi-weekly changes i n the number of organisms per square foot sample found i n the centers and edges of ponds studied i n 1957. 1958 and 1959 Center  Edge  Mean Edge and center  Date  May June July  Number of organisms  Limits level  Number of organisms  Limits  0.05  0.05  level  Number of organisms  level  95.0 296.4 220 i 6 267.9 345*9 510.1 433.6  67.8 145.6 68.6 111.5 122.1 227.7 248.3  93*5 118.1 105.7 160.0 223.8 322.2 547.9  93-9 60.3 51.1 62.0 101.8 195.2 327.8  94-3 208.7 I65.I 216.6 287.2 417.7 488.8  51.5 81.2 44-6 74.2 79.3 148.0 192.4  1-15 16-31 1-15  16-30 1-15  16-31 Aug. 1-15  Appendix 4.  Limits  0.05  Occurrence of edge fauna i n the study ponds in 1957, 1958 and  1959  Occurrence of fauna Organism  ;  Number of ponds Hirudinea Amphiopoda . Hydracarina Ephemeroptera Odonata Hemiptera Trichoptera Coleoptera Diptera Gastropoda  37 43 13 8 2730 46 45 52  Total  53  U  1957 Per cent  Number of ponds  69.8 81.1 24.5 15.1 51.0 56.6 86.8 84.9 98.1 83.0  53 61 19 24 21 38 57 63 72 37 76  1958 Per cent  :  69.7 80.3 25.0 31.6 27.6 50.0 75-0 82.9 94-7 48.7  Number of ponds  1959 Per cent  11 9 17 2 7 16  25.6 20.9 39.5 4.7 16.3 37.2  38. 41 27  88.4 95.4 62.8  26  43  6O.5  - 74 -  Appendix 5.  Volume and mean proportion of plant foods found i n the g u l l e t s of 96 adult mallards c o l l e c t e d i n 1957, 1958 and 1959  Plant  Volume of food (milliliters)  tr Sparganiaceae Sparganium sp. Gramineae 252.9 Hordeum vulgare L. Triticum aestivum L. Echinochloa c r u s g a l l i (L.) Beauv. Beckmannia syzigachne (Steud.) Pern. Seolochloa festucacea (Wild.) Link Agropyron repens (L.) Beauv. Setaria v i r i d u s (L.) Beauv. Cyperaceae 1.2 Garex sp. Scirpus sp. Eleocharis sp. Lemnaceae tr Lemna sp. Polygonaeeae 0.7 Polygonum lapathifolium L. Convolvulus L. Hydropiper L. Rumex p e r s i c a r i o i d e s L. maritimus L. Chenopodiaceae 76.4 Chenopodium album L. Ceratophyllaceae 0.1 Ceratophyllum demersum L. Rosaceae 0.1 Rosa blanda A i t . Leguminosae tr M e l i l o t u s alba Desr. Halorgaceae 0.1 Myriophyllum exalbescens Fern. Compositae tr Sonchus arvensis L. oleraceus L. TOTAL PLANTS  331.5  Mean proportion of food (per cent) tr  24.6 148.9  12.0  38.1 0.1 0.1 tr tr  tr tr tr tr  9.6 2.9  65.7  0.5 1.2  tr tr  0.5  tr tr  tr 0.1  0.5 0.1 tr 0.1 tr  20.0  0.1 tr tr tr tr  20.0  76.4 tr 0.1 0.1  tr  0.2  0.2  tr 0.1 0.1  0.1 tr  tr tr  tr tr  45.7  - 75 -  Appendix 6.  Volume and mean proportion o f animal foods found i n the g u l l e t s of 96 adult mallards c o l l e c t e d i n 1957, 1958 and 1959  Animal  ANNELIDA Hirudinea ARTHROPODA Crustacea Amphiopoda Arachnoidea Hydracarina Insecta Ephemer o pter a Odonata Anisoptera Zygoptera Hemiptera Notonectidae Corixidae Trichoptera Coleoptera Haliplidae Dytiscidae Gyrinidae Hydrophilidae Hydraenidae Chrysomelidae Staphylinidae Unidentified Diptera Tipulidae Culicidae Tendipedidae Ceratopogonidae Stratiomyiidae Anthomyiidae Hymenoptera MOLLUSCA Gastropoda Lymnaeidae Planorb idae Physidae Unidentified TOTAL ANIMALS  Volume o f food (milliliters)  Mean proportion o f food (percent)  0.7  5-0 5.0  1.0  0.9 tr  0.9  tr tr  0.9  5.5 7.0 8.3 0.1 0.8  80.0 10.1  0.2  1.7 3.8 tr  17.8 3.3  3- 0 6.1 0.1  0.8 2.0 0.3 0.1  tr 0.1 0.1 0.2  tr tr tr  0.1  24.6 2.3 0.2 19.8  4- 5  1.5  63.2 tr  tr  2.1 0.1  3.6 0.3 tr  tr  tr  1.2  1.7  0.2 0.3 0.3 0.4  0.4  0.9  0.1 0.3 187.1  tr  0.2  0.5  73.1  1.0  tr  tr 0.1 15.3  0.7  54.3  - 76 -  Appendix 7«  Volume and mean proportion of plant foods found i n the g u l l e t s of 62 juvenile mallards c o l l e c t e d i n 1957, 1958 and 1959  Plant  Unidentified plants  Volume of food (milliliters) .  Sparganiaceae Sparganium sp. Zosteraceae Potamogeton p u s i l l u s L. pectinatus L.  0.5  tr  0.3  0.9 0.2 0.1 "  Polygonaceae Polygonum convolvulus L. Rumex p e r s i c a r i o i d e s L.  0.1  2.7 -1.6 1.1 4.7  0.2 5.0 6.8 0.4 0.5  0.8 0.1  .11.5 4.3  12.4  Lemnaceae Lemna sp.  0.9 1.9 1.8 0.1  .  0.1 0.5  Chenopodiaceae Ghenopodium album L.  0.1  Leguminoseae Melilotus alba Desr.  tr  Haloragaceae Myriophyllum exalbescens Fern.  0.2  Labiatae Teucrium occidentale Gray  0.1  TOTAL PLANTS  0.4  tr  Gramineae . . I5.8 Hordeum vulgare L. Scoloehloa festucacea (Wild.) Link Cyperaceae Scirpus sp. Carex sp. atherodes Spreng. Eleocharis p a l u s t r i s (L.) R. & S.  Mean proportion of food (percent)  0.1 tr  0.1 tr  tr tr  0.1  tr tr 0.1  0.2  0.1 tr  0.1 30.0  9.0  tr  - 77 Appendix 8 .  Animal  Volume and mean proportion o f animal foods found i n the g u l l e t s of 62 juvenile mallards c o l l e c t e d i n 1957, 1958 and 1959 Volume o f food (milliliters)  BRYOZOA piumatellidae (Plumatella repens L.) 51.2 ANNELIDA Hirudinea 4*9 ARTBROPODA Crustacea Amphiopoda 6.2 Arachnoidea Hydracarina 0.1 Insecta Unidentified insects 5.1 Ephemeroptera 0.1 Odonata 8.3 Anisoptera Zygoptera Hemiptera 2.7 Notonectidae Corixidae Gerridae Saldidae Triehoptera 46.2 Coleoptera 2.6 U n i d e n t i f i e d coleoptera Haliplidae Dytiscidae Hydro ph.il idae Curculionidae Diptera 56.6 U n i d e n t i f i e d diptera Tendipedidae Geratopogonidae Stratiomyiidae Tabanidae Syrphidae Anthomyiidae Hymenoptera 0.1 MOLLUSCA Gastropoda 36.O Lymnaeidae Planorbidae Physidae CHORDATA Pisces 1.7 TOTAL ANIMALS 221.8  Mean proportion (per cent)  3.7 1.2 2.8 tr  3.3 tr  6.0 4.0 4.3 0.6 2.0  2.6  0.3 2.2  tf  tr  0.1 0.4 0.4 1.2 0.4 0.2  1.5 4.5  0.1  22.6 5.4  31.4  '0.5 50.7 0.2 0.8 4.3 0.1  1.7 1.3 0.8 0.8 0.8 1.8 26.4 0.8  1.0 1.3  tr  0.3  tr tr  11.2 8.5 0.5 2.2  34.7 0.7 0.6 0.5 91.0  - 78 -  Appendix 9.  Plants found i n the gizzards of 211 adult (A) and 135 juvenile (J) mallards c o l l e c t e d i n 1957, 1958 and 1959  Sparganiacea Sparganium sp. Zosteraceae Potamogeton sp. pectinatus L. p u s i l l u s L. Gramineae Beckmannia syzigachne (Steud.) Fern. Ichinochloa c r u s g a l l i (L.) Beauv. Eordeum jubatum L. vulgare L. Phleum pratense L. Scolochloa festucacea (Wild.) Link Setaria v i r i d i s (L.) Beauv. Triticum aestivum L. P u c c i n e l l i a H u t t a l l i a n a (Schultes) Hitchc.  A J  J A J A J A A J J A J A A J A J A A  Cyperaceae Garex sp. atherodes Spreng. a q u a l i l i s Wahlerib. sychnoeephala Carey Eleocharis sp. p a l u s t r i s (L.) R. & S. Scirpus sp. acutus Muhl. americanus Pers. heterochaetus Chase paludosus Nels. Validus Vahl.  A J J A A A J A J A J A J A J A J A J  Lemnaceae Lemna minor L. t r i s u l c a L.  A J A J  Polygonaceae Polygonum sp. aviculare L. Convolvulus L. Hydropiper L. lapathifolium L. P e r s i c a r i a L. Rumex sp. maritimus L. mexicanus Meisn. p e r s i c a r i o i d e s L.  A A A A A A A A  J J J  J J J  - 79 -  Appendix 9.  Plants found i n the gizzards of 211 adult (A) and 135 juvenile (J) mallards c o l l e c t e d i n 1957, 1958 and 1959  Chenopodiaceae Chenopodium album L.  A J  Cruciferae B r a s s i c a sp. Rorippa i s l a n d i c a (Oeder) Borbas Saxifragaceae Saxifraga cespitosa L.  A  Caryophyllaceae Silene n o c t i f l o r a L.  A  Ceratophyllaceae Geratophyllum demersum L.  A J  Rosaceae Geum t r i f l o r u m Pursh P o t e n t i l l a sp. Rosa blanda A i t Rub us sp* Leguminosae Astragalus tenellus Pursh Melilotus alba Desr.  J A  A J A 3"  A A J  Onagraceae Gaura coccinea Pursh  A.  Haloragaceae Myriophyllum exalbescens Fern.  A J  Hippuridaceae Hippuris v u l g a r i s L. TJmbelliferae  A A J  Cornaceae Cornus sp.  A  Polemoniaceae Collomia l i n e a r i s Nutt. Verbenaceae Verbena sp.  A  A  -  Appendix 9.  80  -  Plants found i n the gizzards of 211 adult (A) and 135 juvenile (J) mallards c o l l e c t e d i n 1957, 1958 and 1959  Labiatae Unidentified Teucrium occidentale  Gray  A J J  Plantaginaceae Plantago sp. eriopoda Torr. E u g e l i i Dene.  A A A  Caprifoliaceae Symphoricarpos o c c i d e n t a l i s Hook.  A  Compositae Agoseris glauca (Pursh) Raf. Antennaria aprica Greene Sonchus arvensis L.  A A J  - 81 -  Appendix 10.  Animals found i n the gizzards o f 211 adult (A) and 135 juvenile (J) mallards c o l l e c t e d i n 1957. 1958 and 1959  BRYOZOAPlumatellidae ANNELIDA Hirudinea  (Plumatella repens L.)  ARTHR0P0DA  Crustacea Amphiopoda Arachnoidea Hydracarina Insecta U n i d e n t i f i e d insects Ephemeroptera Odonata Anisoptera Zygoptera Hemiptera Corixidae Gerridae Saldidae Trichoptera Coleoptera U n i d e n t i f i e d coleoptera Haliplidae Dytiscidae Hydrophilidae Chrysomelidae Curculionidae Diptera U n i d e n t i f i e d diptera Tipulidae Culieidae Tendipedidae Ceratopogonidae Stratiomyiidae Taoanidae Anthomyiidae Hymenoptera MOLLUSCA Gastropoda Unidentified gastropoda Lymnaeidae Planorbidae Physidae  J A J A J A J A J A J A A J A J A J  J J A J  A A A A A  J  J J  J J J  A A A A A  J  J J J J AJ J  A AJ A J A J  - 82 -  Appendix 11.  lean proportion of plant and animal foods consumed by adult and young mallards during the summers of 1957, 1958 and 1959 Mean proportion  / -o • •. i •J 'Bi-weekly period  April 16-30 May 1-15 16-31 June 1-15 16-30 July 1-15 16-31 Aug. 1-15  Confidence limits 0.0 level  Sample size  5  Plant  Animal  67.4 53.5 24.9 27.6 14.3 8-5 3.8 19.5  32.6 46.5 75.1 72.4 85-7 91.5 96.2 8O.5  15.2 26.6 23.7 16.2 33.8 14.3 3-3 16.7  Adult  Young  35 14 13 27 2 2 2 1  2 2 5 13 24 16  

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