The last bastion of the Adelie in the Antarctic Peninsula | Polarjournal
Over the past forty years, dramatic changes have been observed in penguins breeding in the Western Antarctic Peninsula. Observations facilitated by the access to the colonies due to the presence of scientific bases, passing sailboats and cruise ships. Image: Camille Lin

The Antarctic Peninsula is the northernmost land of the Antarctic continent and is home to populations of Adelie penguins. They have been declining at a worrying rate for several decades, yet a population is resisting in the extreme northeast.

Along the Antarctic Peninsula, is a region that could be called “the Adelie Gap”, where Adelie penguins do not form any colonies. It is a stretch of coastline between Antwerp Island to the south and King George Island to the north. Everywhere around this empty area, this species has been declining for decades, except in the extreme north of the peninsula, northeast of the “gap”, where against all odds they thrive.

A fact reported by a team of researchers, including Michael Wethington of Stony Brook University in New York State. Some members of the team went there during the last austral summer, aboard theArctic Sunrise, a ship of the NGO Greenpeace. The tip of the Antarctic Peninsula would therefore be important for the safeguard of this species, the team of researchers demonstrates and publishes their results in Nature last week.

The discovery comes from the exploration of some areas of the peninsula, from where little information had been reported until now. Some members of the team visited the surroundings of penguin colonies that had not been inventoried or that were not well monitored. They counted the number of adults and pups that each colony was raising. For some, the youngsters had already left their nest to join chicks crèches.

The researchers had to make use of drones to perform their count from aerial pictures. When this was not possible, they used hand-held counters while landing, repeating this count 3 times to minimize measurement errors.

Ice stability

To their surprise, some known colonies were empty, although the presence of guano betrayed the past existence of seasonal gatherings of penguins during the breeding season.

This was the case on Dundee Island near the Antarctic Petrel base for example, in the Weddell Sea. Despite these changes in colony distribution, the researchers found that the Adelie penguin population in the northeast of the “Adelie Gap” has been stable, and sometimes increasing, for more than 30 years.

A few colonies in this region, such as Devil Island, Paulet Island, and Brown Bluff, are regularly visited by commercial cruise ships, and these provide the only consistent time series available for penguin colonies in the region. Image: Camille Lin

These penguins depend on the pack ice. It serves as a resting place and support for future prey, such as krill, which begins its growth under the ice. The retreat of the pack ice can, depending on the place and the species, move the penguins away from their feeding area, or bring them closer to fish-bearing open water. The authors of the study admit that “the link between sea ice and the trend of penguin populations remains very intuitive given the quality of the data”.

However, the authors assure that for Adelie penguins, “even though most discussions focus on their losses, our discovery brings hope knowing that where sea ice is stable, Adelie populations remain robust. It would seem that the rather stable ice conditions of the northern Weddell Sea facing the northeastern Antarctic Peninsula would be a refuge area for these animals in a future climate and would deserve “a special protection status against other types of disturbances, which are in addition to the climatic disturbances.

Camille Lin, PolarJournal

Link to publication: Wethington, M., Flynn, C., Borowicz, A., Lynch, H.J., 2023. Adélie penguins north and east of the ‘Adélie gap’ continue to thrive in the face of dramatic declines elsewhere in the Antarctic Peninsula region. Nature, Sci Rep 13, 2525.

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