Behavioral responses of Adelie penguins confronting a giant ice floe

Abstract

Recent rapid environmental changes in Antarctica have often produced a sudden barrier to the marine animals. Adelie penguins, one of the top predators in the Antarctic ecosystem, are reported to confront the changes near the habitats by the appearance of large icebergs or drift ice. We tracked the foraging trips of Adelie penguins with GPS and time-depth recorders during the chick-guarding period in December 2018, at Adelie Cove in the Ross Sea, Antarctica, when 240 km2 of a giant ice floe was approaching near the foraging areas. Here, we aimed to investigate how Adelie penguins respond to these natural obstacles. Our results showed that, among the 18 penguins, 4 individuals moved to the south of the Silverfish Bay fast ice and 14 moved further east beyond the large ice floe to the sparse drift ice. The 14 birds on the sparse ice either crossed (through the ice floe surface, n = 7) or bypassed (to the northern ice boundary, n = 2; to the southern ice boundary, n = 5). Compared to a neighboring population on Inexpressible Island, Adelie Cove penguins had a longer foraging trip duration and movement distance. Our results suggest that the giant ice floe could alter the foraging paths and penguins bypassed or crossed the ice to reach their foraging areas by spending more energy and time. For better understanding, further studies are required to estimate if penguins suffer from these changes.