What had been the planet’s largest penguin colony no longer holds that title. New research finds chinstrap penguins on Zavodovski Island in the South Sandwich chain near Antarctica have plunged 63% since 2011, from roughly 1.09 million breeding birds to 402,000 in 2025, according to the British Antarctic Survey, whose study was published Wednesday in Current Biology. “It is an enormous population crash,” says study author Norman Ratcliffe, per the Guardian.
AFP reports the team blames climate-driven shifts in the Southern Ocean food web that have pushed krill—the birds’ main prey—into colder waters the chinstraps don’t tolerate. Macaroni penguins, which eat a broader menu, have grown from about 338,000 to 433,000 on the island and now dominate. Scientists say the sharp decline should prompt the International Union for Conservation of Nature to upgrade chinstraps from “least concern” to “endangered.” Cape Adare’s Adelie penguins, which live on the other side of Antarctica, now make up the world’s largest penguin colony.