The penguins that frolic here on the Antarctic sea ice are Adélie penguins. Apart from the emperor penguin, they are the only penguin species that live and breed not only on the offshore islands of Antarctica, but also on the coasts of the Antarctic mainland. The fact that the Adélie penguins captured here in the photo are on the sea ice is probably no coincidence: Unlike most penguin species, it is assumed that Adélie penguins carry out their annual moult away from the breeding colonies on the sea ice.
This behavior makes it particularly difficult for researchers to investigate this period. The study by Annie Schmidt from Point Blue Conservation Science in Petaluma, California, highlights the central role of seasonal Antarctic sea ice in the annual moulting period for Adélie penguins in particular. They fear a potential bottleneck in the penguins’ annual cycle, which could worsen as climate change progresses.
Using data from some geolocating diving recorders, the researchers were able to detect longer gaps in diving activity after the breeding season, which indicate the moulting period. From 2017 to 2019, the dive recorders were used year-round, collecting data from 195 adult penguins in the Ross Sea.
Using their location data, two important moulting areas were identified. Studies using satellite-based remote sensing data showed a significant decrease in sea ice concentration during the moulting period, especially in the main moulting area. This is linked to a decline in the annual return rate of penguins to breeding colonies over the last 20 years: for every 10% decrease in sea ice concentration in moulting areas, 2.4 to 4.8% fewer penguins returned. The researchers’ focus is on the challenges that the penguins could face, especially with regard to changing climate conditions.