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Brett A. DeGregorio

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Body mass in overwintering waterfowl is an important fitness attribute as it affects winter survival, timing of spring migration, and subsequent reproductive success. Recent research in Europe and the western United States indicates body mass of mallards (Anas platyrhynchos) has increased from the late 1960s to early 2000s. The underlying mechanism is currently unknown; however, researchers hypothesize that increases are due to a more benign winter climate, increased food availability through natural and artificial flooding, introgression of wild mallard populations by game-farm mallards, or shifting of wintering distributions northward. Further investigation of factors related to winter mallard body mass increases...
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