Researchers claim that polar bears are facing a severe risk of starvation as they are forced to spend longer periods on land due to climate change.

The study, published in the journal Nature Communications, used collar cameras to examine the behaviour and energy expenditure of polar bears in the western Hudson Bay region of Manitoba, Canada during extended ice-free seasons.

Lead researcher Anthony Pagano, a wildlife biologist with the U.S. Geological Survey Polar Bear Research Program, said that polar bears are struggling to find enough food to sustain themselves on land.

Despite trying various strategies such as resting, scavenging, and foraging, nearly all of the polar bears observed in the study lost weight rapidly, with some losing as much as a kilogram per day.

Researchers found that polar bears relied heavily on seals and their energy-rich fat to maintain their massive size. Without access to their preferred prey, polar bears are unable to sustain themselves on terrestrial foods and are at risk of starvation.

Co-author Charles Robbins, director of the Washington State University Bear Center, said: 'Our findings show that polar bears cannot survive on land for extended periods of time. Their specialised diet and hunting behaviours make them highly vulnerable to the effects of climate change.'

With the ice-free period continuing to grow and polar bear populations already in decline, the researchers warned that increasing starvation rates could have devastating consequences for the species.

The research was supported by several organizations including the National Science Foundation, Environment and Climate Change Canada, and Polar Bears International.