Time-Activity Budgets of Diving Ducks Wintering in South Carolina

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Abstract
We determined nocturnal and diurnal time-activity budgets from focal individual sampling for buffleheads (Bucephala albeola), lesser scaup (Aythya affinis), ring-necked ducks (A. collaris), and ruddy ducks (Oxyura jamaicensis) wintering on a reservoir in South Carolina. Foraging and sleeping dominated the time-activity budgets whereas time spent in aggression and courtship was low. Buffleheads spent more time foraging (69%) than other species (41, 43, and 33% for lesser scaup, ring-necked ducks, and ruddy ducks, respectively) during the diurnal period. Female lesser scaup and ring-necked ducks foraged more (44 and 48%, respectively) than males (39 and 40%, respectively) (P < 0.05). Time spent feeding increased throughout the winter among buffleheads, lesser scaup, and ring-necked ducks (P < 0.05). Buffleheads fed most early in the morning and ruddy ducks spent more time feeding late in the day (P < 0.05). Ruddy ducks also fed more at night (42%) than during diurnal hours (31%), in contrast to other species in the study. The other 3 species also fed at night, but were not as active as ruddy ducks. This study illustrates the need to collect diel behavior data to document activity.