Giant iceberg blocks feeding route, causing 69% drop in penguin chicks
A 14-km iceberg that grounded near Coulman Island forced emperor penguins to travel farther for food, leading to a 69% decline in chick numbers during the 2025 breeding season.
During the 2025 breeding season, a newly calved iceberg measuring about 13.9 km by 4 km drifted toward Coulman Island and became grounded 3-5 km north of the emperor penguin colony. Its presence forced adult birds to take a considerably longer route to reach open-water feeding areas, limiting the frequency of chick provisioning. Aerial counts in November-December recorded 6,658 live chicks, representing a 69 % reduction compared with 2024 and the 2017-2024 average.
Scientists noted that while sea-ice conditions remained generally good, the iceberg acted as a physical barrier that impaired access to essential resources. The researchers caution that the findings reflect a single season and demonstrate correlation rather than proven causation, underscoring the need for longer-term monitoring. The work expands understanding of how transient ice features, alongside climate trends, can affect Antarctic species’ reproductive success.
Why it matters
It shows that sudden ice changes can quickly threaten penguin populations, highlighting fragile Antarctic ecosystems.
In this story