Variability in behavioural response of wintering black ducks to increased energy demands.

Anas rubripes were studied wintering at 3 sites differing substantially in food quality (energetic value) and quantity. All behaviours other than preening showed some variation in response to environmental factors, with temperature consistently explaining the greatest amount of that variation. However, the ducks' response to cold temperature was not consistent between sites. One can only predict the specific response of ducks to increased energetic demands (colder temperatures) by knowing the quality and quantity of food available in addition to the cost of foraging. -from Authors