The behavioral ecology of the American Wigeon (Anas americana) over its annual cycle
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Date
1983-03-31T16:52:17Z
Authors
Wishart, Richard A.
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Abstract
The behavioral ecology of the American Wigeon (Anas americana) was
studied over its annual cycle in western Canada between 1974 and 1978.
The objective of this work was to examine the cross-seasonal interactions
of the biology and behavior of the wigeon as they underlie the evolution
of its mating system.
The wigeon was more herbivorous than any other dabbling duck studied
so far and spent a considerable amount of time feeding in upland
habitats. Vegetation was important in the diet year round but
particularly from late summer through the winter. Plant seeds were a
rich source of protein and carbohydrate early in the spring. During
breeding stages animal foods were selected by wigeons, particularly
females. Wigeons usually did not feed on small crustaceans and
gastropods but selected larger aquatic insect foods.
Relative to other Anas soecies, the wigeon has a goose-like bill
whose structure facilitates feeding on upland and aquatic vegetation.
With the evolution of this specialization, efficient surface-straining of
small foods has been sacrificed. To increase food digestibility, wigeons
altered gizzard grit composition and organ sizes. Through these
mechanisms I have demonstrated how wigeons have been able to increase the
efficiency of digestion.
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Keywords
American Wigeon, wigeons, behavioral ecology, dabbling duck, Anas americana, wigeon breeding stages, wigeon feeding habits