Effects of environmental parameters on the foraging behavior of three species of wintering dabbling ducks (Anatini)

• Published in: Canadian Journal of Zoology
• Main Author: Hepp, Gary R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1985
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Anas acuta
• Online Access: http://dx.doi.org/10.1139/z85-044; http://www.nrcresearchpress.com/doi/pdf/10.1139/z85-044

Foraging behaviors of wintering gadwall (Anas strepera), pintail (Anas acuta), and green-winged teal (Anas crecca carolinensis) were studied at Bodie Island, North Carolina. Foraging speed (metres per minute) and rate of foraging (dips per minute) did not differ by sex, but significant monthly variation of foraging components occurred for all species. Ducks fed at faster rates and increased their foraging speed as winter progressed. Stepwise multiple regression procedures were used to test the effects of day length (minutes), mean daily temperature (degrees Celsius), mean daily wind speed (kilometres per hour), water depth (centimetres), and density of foraging individuals on the temporal variation in rate and speed of foraging. Changes in the foraging speed and rate of dipping of winter ducks were significantly related to decreases in day length and average daily temperatures. Other environmental parameters had variable effects on foraging behavior. Estimates of total prey biomass did not vary significantly during winter; however, changes in the distribution of prey sizes may have contributed to changes in foraging behavior. Greater foraging speed and rate of dipping may have been a behavioral mechanism which increased ingestion rate and minimized foraging time, thereby allowing wintering ducks to reduce thermal stress through modification of activity patterns and selection of more favorable microclimates.