Aerial surveys indicate that chinstrap penguin populations on Zavodovski Island, part of the South Sandwich Islands near Antarctica, have experienced a substantial decline between 2011 and 2025. The research, led by the British Antarctic Survey, documented a reduction of 63% in occupied nests during this period, causing the island to lose its status as home to the world’s largest penguin colony.
Researchers attributed the decline primarily to climate-driven environmental changes affecting the birds’ food sources and survival rates. The warming of ocean temperatures has pushed krill populations southward, reducing food availability for chinstrap penguins, which maintain a specialist diet focused on this food source. Geographical constraints, including sea-ice patterns and limited nesting sites further south, prevent the birds from following their prey to new locations. Other potential factors were examined, including volcanic activity from Mount Curry and competition with migrating humpback whales, though data suggests climate-driven ocean food supply shifts remain the fundamental cause.
A notable contrast emerged during the study period: macaroni penguins on the same island increased in numbers. Scientists attribute this difference to the macaronis’ more adaptable diet, which includes fish and other crustaceans in addition to krill. Tracking data showed macaroni penguins foraged in warmer northeastern waters, allowing them to supplement their traditional food sources. This compositional shift represents what researchers described as the most significant change in Antarctic penguin community composition ever observed at a single location.
The research involved a 15-day voyage to the remote island, where scientists employed drones, aerial photography, and satellite imagery alongside tracking devices fitted to 20 birds. The findings, published in Current Biology, suggest chinstrap penguins may now warrant official endangered status. The title of world’s largest penguin colony has effectively transferred to Cape Adare in the Ross Sea, located more than 5,000 kilometers away on the opposite side of Antarctica.
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