Diel diving behavior of breeding gentoo penguins on King George Island in Antarctica

Abstract

Many marine birds dive to catch prey in water. The gentoo penguin (Pygoscelis papua), a specialized diving seabird that preys on krill and fish, is distributed from the sub-Antarctic islands to Antarctic regions. Here, we observed the diving behavior of breeding gentoo penguins on King George Island, South Shetland Islands, Antarctica. Using a time？depth recorder, we collected diving depths every second from seven gentoo breeders for 5？21 days during the chick-rearing period and analyzed their diving characteristics. Most dives occurred in shallow water, although the dive efficiency (=bottom duration time/[dive duration + post-dive surface time]) was highest at depths of 30？35 m and decreased as the penguins dove deeper. Gentoo penguins did not dive more frequently during the day than at night, but during nighttime, most dives occurred in shallow water (