Polar bears can't survive on land-based diet: study

While some polar bears are hunting on land more often in areas hit by climate change, a diet of bird eggs and berries cannot sustain these huge animals, a new study has found.
A handful of polar bears have been spotted snacking on land-based foods to supplement their traditional diet of seals and marine mammals.
Researchers wondered whether the high-protein, high-carbohydrate foods polar bears eat on land - such as caribou and berries - could help them survive, as sea-ice loss makes seals harder to snatch, 'Live Science' reported.
According to a review of previous research on bear diets, polar bears spend so much energy searching for berries or chasing down caribou that they reap little caloric reward from these meals.

"A really large bear has high energetic costs when they get up to forage, and these [terrestrial] resources are typically lower in calories or widely dispersed," said Karyn Rode, lead study author and a US Geological Survey research wildlife biologist in Anchorage, Alaska.
Even if a few polar bears do make bird eggs and other terrestrial foods an important part of their diet, the bears may gobble so many eggs that they might decimate the Arctic seabird population.

"Terrestrial foods can't offer polar bears what they need at a population level," Rode said.
Global warming has reduced the amount of Arctic sea ice near shore, especially in the late spring when polar bears hunt for seal pups before moving onto land for the summer.

Polar bears mainly hunt for seals on the sea ice. The shrinking sea ice is sending the bears to shore earlier in the season in some areas of the Arctic, such as Hudson Bay, Canada, and their arrival overlaps with hunting opportunities for geese, eggs and caribou.
The review was published in the journal Frontiers in Ecology and the Environment.