14km iceberg cuts penguin food supply; chick numbers fall 69%

An iceberg nearly 14 kilometers long has disrupted the feeding routine of a colony of emperor penguins on Coulman Island in Antarctica, causing a sharp decline in the number of chicks born. The iceberg blocked the penguins' primary route to their feeding grounds, forcing the adults to travel longer distances to find food for their offspring.

According to a research report published in Communications Earth & Environment, the number of emperor penguin chicks at Coulman Island declined by 69 percent in the 2025 breeding season, from 7,493 chicks in 2024 to just 6,658 chicks in 2025. This represents a significant drop compared to the average chick count from 2017 to 2024.

While the overall sea ice conditions were favorable, researchers discovered that the grounded iceberg, measuring approximately 13.9 kilometers by 4 kilometers, had a substantial impact on the penguins' ability to access food. Emperor penguins rely on stable sea ice for nesting and reliable access to open water feeding areas where they hunt fish, squid, and krill.

The iceberg's presence forced the adult penguins to take a longer route to the feeding grounds, resulting in reduced feeding frequency for the chicks. The research highlights the vulnerability of emperor penguins to localized environmental changes, such as the presence of large icebergs, in addition to the well-known threats posed by changing temperatures and melting ice.

The study emphasizes the need for continued monitoring to understand the complex impacts of climate change and natural events on the delicate balance of the Antarctic ecosystem.