Not everyone agrees with the new paper's conclusions, which suggests that polar bears can't survive on berries and eggs over a seal diet.
Scientists don’t think polar bears have much of a chance if they are forced off of sea ice due to global warming, arguing that land food won’t adequately replace fat-laden seals in their diets.
Studies that indicate the bears could survive off bird eggs, berries, and other land foods are off-base, according to a review paper that was published recently in the journal Frontiers in Ecology and the Environment, as reported by the Associated Press.
The paper, which reviews current research on polar bears, examines the idea that land food is becoming more important to polar bears and could increase their changes of survival if sea ice continues to recede, making seal hunting much more difficult.
Karyn Rode, a U.S. Geological Survey research wildlife biologist and the lead author of the paper, said that bears aren’t using land food much, and when they do, it doesn’t replace the fat-rich seals.
However, not everyone is accepting the conclusions of the paper, indicating just how controversial the issue is among scientists. Robert Rockwell, a biologist and ecologist at City College of New York, said in the AP report that he had conducted research in the Hudson Bay for decades and had watched polar bears adapt to eat goose eggs and caribou calves, so he found it “hard to believe” that they wouldn’t be able to handle the change.
The world is currently down to about 19 polar bear populations distributed into four regions. In three of them, the entire population stays on the sea ice year-round, relying on a diet of seals for sustenance. The fourth includes the Hudson Bay, which has season sea ice and allows the polar bear to spend time on land.
The polar bear was listed as a threatened species in 2008 by the Bush administration due to its loss of sea ice in the summer, and climate models that suggests that polar bear distribution had been declining.
Although there is evidence that bears are using some terrestrial sources for food, those that eat berries lose a lot of weight and eggs just aren’t enough, Rode said according to the report. Another author of the paper, Steven Amstrup, chief scientist at Polar Bear International and a retired USGS polar bear researcher, said that hte paper establishes that polar bears are unlikely to be able to handle a land-based diet, and that makes it critical to save the sea ice.
