ANCHORAGE, Alaska — A organisation of researchers contend frigid bears forced off melting sea ice will not find adequate food to reinstate their stream diet of fat-laden sea mammals such as seals, a end that contradicts studies indicating that bears might be benefiting from bird eggs, berries and other land food sources.
Few bears are regulating land food and what they find can’t reinstate lipid-rich ringed or bearded seals, pronounced Karyn Rode, a U.S. Geological Survey investigate wildlife biologist and lead author of a examination paper published Wednesday in a journal, Frontiers in Ecology and a Environment.
The paper by sovereign and educational researchers reviews stream frigid bear research. It’s directed during new investigate documenting bears feeding on land and suggestions that those dishes are apropos some-more critical for them, that could boost their possibility for presence as summer sea ice recedes, preventing sign hunting.
But not everybody agrees with a conclusions reached by Rode and a other authors during Washington State University and Polar Bear International.
Robert Rockwell, a race biologist and ecologist during City College of New York, who is also dependent with a American Museum of Natural History, has conducted investigate during western Hudson Bay for 47 years. He has watched frigid bears change their function to eat crow eggs and caribou calves, he pronounced Tuesday.
“I find it tough to trust they’re going to get zero out of it,” he said.
Polar bears are sea mammals that spend many of their lives on sea ice. They use a solidified sea to hunt, mostly throwing ringed seals.
The world’s 19 frigid bear populations are divided into 4 regions. In three, whole populations historically remained on sea ice year-round. The fourth has anniversary sea ice and includes Hudson Bay, where frigid bears have always spent time on land.
The Bush administration in 2008 listed frigid bears as threatened since of an shocking detriment of summer sea ice and meridian models indicating vital declines in frigid bear placement and abundance.
Land food such as berries can be abounding for frigid bears though low quality, Rode said. Eggs from belligerent nests are aloft peculiarity though limited. Polar bears feeding on berries remove poignant weight, Rode said.
“There is justification that some bears are regulating human sources in a place such as Hudson Bay, though there’s been no justification that it’s contributing a poignant volume to their appetite requirements,” Rode said.
Land food might advantage individuals, though a altogether grant to frigid bear diets substantially will be negligible, a authors said.
“This paper establishes in no capricious terms that frigid bears are really doubtful to be means to make a vital on land, and that if we don’t save a sea ice, frigid bears will indeed be gone,” pronounced another author, Steven Amstrup, arch scientist during Polar Bear International and a late USGS frigid bear researcher, in an email statement.
Polar bears on land face foe for food from Arctic foxes, birds and grizzly bears. Rode said. Arctic grizzlies are among a smallest of their species.
“Food stipulations would be quite cryptic for a many incomparable frigid bears, that mostly have a physique mass double that of Arctic brownish-red bears,” a authors said.
Studies suggesting frigid bears have benefited from food on land have not assessed a food’s enterprising contribution, Rode said. The ultimate indicator of any food advantage would be their health, she said.
“In western Hudson Bay, where some-more high-quality human food (birds, bird eggs, and caribou) might be some-more straightforwardly accessible than in many other Arctic landscapes, presence rates and race distance have declined with augmenting time spent on land notwithstanding human foraging,” a authors said.
Rockwell pronounced a paper might be regulating old-fashioned information. The paper cites western Hudson Bay frigid bear investigate from some-more than a decade ago, before bears started entrance ashore early to feed on sleet geese and caribou calves, he said.
Rode and her colleagues have underestimated a series of bears eating food on land and bonus that they can learn new behavior, he said. One bear he documented raided 250 eider nests in 96 hours and filled 20 percent of a annual caloric intake.
“My 47 years of knowledge tells me these bears are changing their behavior,” he said. “How many is that going to advantage them? we don’t know. It’s got to advantage them some. If we eat a eggs from 40 nests, afterwards we only consumed a same series of calories as if we ate a seal.”
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