June 2020
Vol 6, Issue 26

About The Cover

Cover image expansion

ONLINE COVER Adélie penguins are considered a sentinel species that can warn of the environmental effects of climate change in continental Antarctica. Most previous studies on how Adélie populations have responded to interannual variations in sea ice have been correlational rather than experimental, and have not examined how foraging behavior could account for links between environmental changes and breeding success. To track foraging behavior in detail across four breeding seasons within the past decade, Watanabe et al. monitored 175 penguins in the Lützow-Holm Bay by tagging them with animal-borne GPS loggers, accelerometers, and video cameras. The 2016-2017 breeding season proved unusual since a large quantity of sea ice in the bay broke up and drifted away with currents, providing a natural experiment by which the scientists could observe penguins foraging in the absence of sea ice. The researchers found that the penguins covered more ground in less time by swimming instead of walking as they searched for prey during that unusually ice-free breeding season. Since climate models predict that the Antarctic will rapidly lose sea ice as the 21st century progresses, the results suggest that Adélie penguins may experience a population boom in the years to come. However, Watanabe et al. note that, according to previous studies, Adélie penguin populations that reside in warmer, sea-bordering regions (about 30% of the species) do not fare well when sea ice diminishes. [CREDIT: YUUKI WATANABE (NATIONAL INSTITUTE OF POLAR RESEARCH, JAPAN)]