Researchers from the British Antarctic Survey (BAS) have documented the loss of more than 500,000 chinstrap penguins on Zavodovski Island, the site of what was formerly the world’s largest penguin colony. A study published Wednesday, Oct. 7, 2026, in the journal Current Biology found that the number of occupied chinstrap nests on the uninhabited volcanic island fell by 63% between 2011 and 2025.
Zavodovski Island, located in the South Sandwich Islands north of Antarctica, is approximately 1,200 miles from the nearest permanently inhabited settlement. It was named the largest penguin colony in the world in 2011. To conduct the recent assessment, researchers traveled from the Falkland Islands, utilizing drones, aerial photography from a British aircraft, and satellite data to survey the population.
The findings, led by BAS penguin ecologist Norman Ratcliffe, indicate an annual population decline of approximately 7%, which is two to three times the rate observed in other colonies. Scientists ruled out a 2016 volcanic eruption, competition for nesting sites, or regional fishing as primary causes. Instead, they identified climate change as the cause, concluding that warming oceans are disrupting the distribution of krill, the chinstrap penguin's primary food source. While chinstrap numbers fell, the island’s macaroni penguin population increased by 28% between 2011 and 2016 and has remained stable since.
The scale of this loss may lead to a change in conservation protections. The species is currently designated as "least concern" by the International Union for Conservation of Nature (IUCN), but researchers state these findings could push the species into a threatened category on the Red List of Threatened Species.
Future steps depend on reassessments by the IUCN and ongoing monitoring of Antarctic food webs. The researchers indicated that chinstrap penguins are unable to follow krill further south into icier waters. No specific date for an IUCN reassessment was reported.