Foraging rhythms in Adélie penguins (Pygoscelis adeliae) at hope bay, Antarctica; determination and control

Summary

We studied diel periodicity in activity of Adélie penguins (Pygoscelis adeliae) during the austral summer solstice and one month later by counting, hourly, numbers of birds leaving colonies to forage, numbers arriving back after foraging, numbers in a colony and numbers resting outside the colonies. During the solstice large numbers of birds were arriving at and departing from the colony at all times of the day although there was a tendency for more birds to be at sea when light intensity was highest at mid-day. Generally, birds not brooding chicks did not rest on land. A month later, when visibility was poor at mid-night, the percentage of birds at sea was highly positively correlated with light intensity. Birds returning from foraging in the evening fed chicks immediately and then either rested in the colonies or on snow patches between the colonies and the sea until the following morning.