DIURNAL ACTIVITY OF ADELIE PENGUINS PYGOSCELIS ADELIAE AT CAPE BIRD

Activity cycles of non-breeding Adelie Penguins were investigated at Cape Bird, Antarctica. There was continuous light during the observation period, but none the less regular fluctuations of light intensity and temperature were maintained. The penguins had no single period of rest, but were active throughout the 24 hours. However, there were statistically significant diurnal variations in the levels of certain activities among non-breeders, with an overall reduction in activity-levels in the middle of the day, especially on warm midsummer afternoons. It is suggested that this cyclic activity minimum may be associated with the low heat tolerance of Adelie Penguins.