New Study - Increasingly Unlikely Polar Bears Will Be Able To Adapt To Hunting, Living On Land
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The review article, "Can Polar Bears Use Terrestrial Foods to Offset Lost Ice-Based Hunting Opportunities," concludes that even though some polar bears are eating on land, those instances are limited and the nutritional benefits of that food is in doubt. "The intent was to clarify what we know now," said the paper’s lead author Karyn Rode, an Alaska-based Research Wildlife Biologist with the U.S. Geological Survey. Rode said the research showed that eating on land may be helping a few bears, there is no evidence it is benefitting them on a population level.
Polar bears have evolved to survive on the sea ice, thriving on fat of the prey they hunt there, mostly ringed seals. Since the beginning of the satellite record in 1979, nearly 700,000 square miles of sea ice have vanished as the Arctic warms at a rate two to three times faster than the rest of the globe. Some polar bear populations, such as those in the Southern Beaufort Sea and the Western Hudson Bay, have shown declines in reproduction rates, health and survival as the bears are forced onto land for longer periods.
Recent work the paper cites has shown that polar bear genes differ from their ancestors, brown bears, because they evolved to metabolize fat. Brown bears live on food found on land, and those that live in the Arctic are some of the smallest in the species.
"The bottom line is that polar bears are really big," Rode said. "And they're big for a reason–they have the highest fat diet … It's the size of polar bears that really causes them problems when they switch their diet."
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http://insideclimatenews.org/news/01042015/eating-land-unlikely-save-polar-bears