Individual Variation of Foraging Behavior and Food Provisioning in Adélie Penguins (Pygoscelis adeliae) in a Fast-Sea-Ice Area

ABSTRACT. To understand the effects of foraging behavior on the amount of food provided to chicks (meal mass and frequency), we monitored nest attendance and diving behavior of 20 Adélie Penguin (Pygoscelis adeliae) pairs that were rearing chicks. Because ice forms on the sea surface at night, parents foraged through cracks or within leads in the sea ice mainly during 0800–2400 hours. Birds that departed the colony in the afternoon and returned in the evening of the same day fed their chicks more frequently than those that made longer trips (i.e., those that departed in the afternoon and returned the next day or departed in the early morning and returned that evening). When the duration of the longest dive bout during each trip was longer, parents brought back heavier meals that contained larger krill. On average, birds made longer dive bouts when diving to greater depths. Thus, daily foraging pattern and foraging depth affected the provisioning rate, but the proportion of time spent foraging during the potential foraging period, total underwater time per day, and parental body condition were not. We suggest that temporal variability in prey availability and individual differences in foraging behavior affect the provisioning rate and, thus, chick growth.