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The spring and summer foods of the common mallard (Anas Platyrhynchos platyrhynchos L.) in south Central Manitoba

University of British Columbia

The mallard is the most important species of North American waterfowl; its breeding range has been reduced and is in danger of a further reduction due to agricultural and drainage practices. To maintain mallard populations at the present level, it will be necessary to control and manage sufficient habitat to provide for their needs. In such a program, the knowledge of the food habits of waterfowl is an essential tool. The objectives of this study were: to determine the spring and summer foods of the mallard, and to determine the relationship between utilization and availability of the various foods. A study of the spring and summer food habits of mallards was conducted from 1957 to 1959 on a 100 square mile study area in south central Manitoba. 211 adult and 135 young mallards were collected for analyses of stomach contents. At the same time, ponds were randomly selected from the study area for examination and analyses of faunal and vegetative characteristics. In the determination of food habits, the gullet contents proved superior to the gizzard contents. The animal foods found in the gizzard were partially digested and could not be measured accurately. There was also the possibility that the hard seeds of aquatic plants persist in the gizzard for a long period of time. The spring and summer foods of adult mallards consisted of 45.7% plant material and 54.3% animal material. The young mallards, on the other hand, consumed 9.0% plant and 91.0% animal foods. In both adult and young birds the Class Insects provided the main source of animal foods, and in both cases, the majority of the insect foods were obtained from the orders Trichoptera and Diptera. In adult mallards the important plant foods were obtained from the G-ramineae and Chenopodiaceae families. A difference.in the feeding habits of adult male and female mallards was found. The male birds consumed more plant foods and less animal foods than did the female birds. Pond fauna increased in abundance until a peak was reached in midsummer then decreased in numbers. On the other hand, seeds increased in abundance in 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 availability of these foods; the importance of plant foods in their diet decreased during the summer, whereas, the importance of animal foods increased. Considerable variations in water levels, from flood to drought conditions, were experienced during the study. As a result of the change in water levels, the amount of emergent vegetation decreased. The food of young mallards reflected this change in habitat; the ratio of plant to animal foods consumed decreased from 1957 to 1959. The animal protein intake of the mallard is variable and the variations in the consumption of animal and plant foods depend upon their availability. The relative proportions of the various foods eaten may not be of primary importance; mallards appear to be able to balance their diets with widely different kinds of food.

Text

2011-12-02

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http://hdl.handle.net/2429/39472

Zoology

University of British Columbia

Graduate