Chinstrap nests on Zavodovski fall 63% in 14 years

A British Antarctic Survey study found that occupied chinstrap penguin nests on Zavodovski Island fell 63% from 2011 to 2025, ending the island’s status as home to the world’s largest penguin colony. Researchers say warming-related changes to the ocean food web are the most plausible explanation, while emphasizing that the proposed cause has not been independently established. The study compared aerial and drone surveys with satellite imagery. It found that the decline began before Mount Curry erupted in 2016 and continued steadily afterward. Researchers therefore do not consider the eruption the main driver of the change. The island’s penguin population has also shifted in composition. Macaroni penguins increased while chinstraps declined, and researchers say macaroni penguins’ broader diet may help explain their relative resilience. The study describes the change in the two species’ balance as a striking shift in the island’s penguin community. Researchers link the chinstrap decline to changes in the availability of krill, a key part of the birds’ diet. They say warming waters have likely shifted krill southward, away from the cooler waters where chinstraps forage.