Scientists studying penguin populations in Antarctica have documented a severe decline at Zavodovski Island, the former site of the world’s largest penguin colony. The research, published in Current Biology, found that chinstrap penguin numbers have fallen by approximately two-thirds over the past 14 years. This represents a loss of roughly half a million breeding individuals from the island, according to Prof Norman Ratcliffe of the British Antarctic Survey, who led the study.
The island housed approximately 600,000 chinstrap penguins and 90,000 macaroni penguins when measured in 2011. Given the documented decline between that time and 2025, the colony has likely lost its status as the world’s largest to Cape Adare in the Ross Sea. The rapid pace of collapse has prompted researchers to consider whether the species should be reclassified as endangered.
Climate disruption is identified as the most probable cause of the chinstrap decline. Antarctic temperatures in the peninsula region have risen approximately 5 degrees Celsius above preindustrial levels, representing one of the fastest warming rates globally. Temperature anomalies have been particularly extreme, with a winter high of 15.4 degrees Celsius recorded at an Argentine research station on the Trinity Peninsula, roughly 20 degrees above normal for the season.
Chinstrap penguins face specific challenges adapting to these conditions due to their specialized dietary preferences and ocean temperature requirements. Tracking data indicates they typically forage in cooler northern and northwestern waters in search of Antarctic krill, their primary food source. As waters warm, krill populations have shifted southward to the Weddell Sea, making them less accessible to the penguins. Macaroni penguins, which have more flexible feeding habits, experienced a 30 percent population increase, though this gain provides minimal compensation for the chinstrap loss.
Researchers excluded alternative explanations for the decline, including inter-species competition, human interference, and volcanic activity from the island’s 2016 eruption. The consistent linear pattern of decline and behavioral data showing chinstraps avoiding the main volcanic deposit areas contradicted a volcanic catastrophe hypothesis. Scientists warn that the loss of chinstrap penguins threatens broader ecosystem stability, as the removal of species components increases collapse risk across interconnected food webs.
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