Polar bears are at risk of starvation during ice-free periods in the Arcticaccording research published in the journal Nature Communications. The findings, based on data from 20 polar bears, provide new insights into how these animals may struggle to cope with longer ice-free periods due to climate change, forcing them to forage on land.

The Arctic is experiencing a rapid decline in sea ice with ongoing climate change. In late spring and early summer, polar bears use the sea ice as a platform to hunt mostly seals when they give birth and wean their cubs. During ice-free periods, bears are believed to minimize their activity to conserve energy and either fast feed or consume terrestrial vegetation. In western Hudson Bay, Manitoba, Canada, the ice-free period increased by three weeks from 1979 to 2015, keeping bears on land for about 130 days over the past decade.

Researchers used GPS tracking devices to track 20 polar bears during the Arctic sea ice-free period (August-September) between 2019-2022 in western Hudson Bay. They tracked their daily energy expenditure, changes in body mass, diet, behavior and movement. They found that polar bears chose different strategies to reduce energy loss, including reducing movement, fasting and eating berries and birds. However, 19 of the 20 bears lost weight quickly, averaging about a pound a day.

As sea ice continues to retreat, understanding these adaptive behaviors, the authors point out, is critical to efforts to support polar bears in a rapidly changing ecosystem.