Foraging Patterns of Adélie Penguins During the Incubation Period

Abstract

We report on the duration of foraging trips taken by Adelie penguins Pygoscelis adeliae during the incubation period at Cape Bird, Ross Island, Antarctica. In years when birds foraged longest, males apparently adjusted the duration of the Second Foraging Trip relative to the time available until hatching. In seasons where the sum of the first two foraging trips was well short of the incubation period, males showed no evidence of adjustment; however, females taking the Third Foraging Trip did. Cues for adjustment of foraging trips were not derived from eggs. Neither did the physiological condition (i.e. time spent fasting before foraging) of the birds affect the duration of foraging trips. It seems that time until chicks hatch is the crucial determinant of time spent foraging. If this is so, and food is not limiting, then attempts to relate foraging trip times to krill stocks may be ill-founded.