Faster-moving sea ice brought on by rapid global warming is adding to physiological stress for polar bears off the coast of Alaska, experts warn.
A study by US Geological Survey researchers and others says the already at-risk bears have to burn more calories to stay within their preferred habitat as sea ice drifts.
Research ecologist George Durner said that adds to problems for polar bears in the southern Beaufort Sea.
Researchers there have documented declining body condition, reproduction and survival among polar bears as diminished sea ice gives them fewer opportunities to hunt for seals.
The study concludes that bears must kill one to three more seals per year to compensate for burning more calories on sea ice that carries bears away from their home range.