Shrinking sea ice is crowding emperor penguins during moulting.

Satellite images show emperor penguins gathering into smaller, denser moulting colonies as Antarctic sea ice in the study area fell sharply between 2022 and 2024; researchers warn this increases the risk of large losses if ice breaks up before moulting finishes.

Satellite images have for the first time identified emperor penguins' moulting colonies along parts of Marie Byrd Land. Moulting lasts three to four weeks and birds cannot enter the sea while they replace their feathers. Researchers report that shrinking and less stable sea ice is forcing penguins into smaller, more crowded moulting groups. Scientists say this clustering raises the chance of mass losses if the ice breaks up while birds are still moulting. Key findings: - Analysts spotted distinctive brown patches on the coast that were identified as moulting colonies for emperor penguins. - During moulting the birds are unable to feed at sea for several weeks, making stable coastal ice important for survival. - Antarctic sea ice in the study area declined markedly between 2022 and 2024, leaving limited fast ice for colonies. - Lead author Dr Peter Fretwell warned of potentially "catastrophic" consequences and said the extinction horizon may be closer, possibly by decades, while noting further analysis is needed. Summary: The observed crowding during moulting increases vulnerability because adult penguins cannot forage at sea while replacing feathers. A separate study of Ross Sea populations is expected in the coming weeks and is expected to report on how many adults may have been lost during recent ice breakups.