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Polar bear losing out to grizzly cousins
Source: Agencies |
November 25, 2010, Thursday
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POLAR bears are likely to lose out to grizzly bears in competition for food as climate change drives the two species closer together into shared habitat, biologists concluded in a study released in the United States on Tuesday.
The research was based on 3D computer modeling that compared the skull and jaw strength of the two and found polar bears ill-suited to the?tougher chewing demands posed by the largely vegetarian diet of their grizzly cousins.
The findings add to mounting signs of threats to polar bears from global warming that scientists attribute to excessive levels of carbon dioxide and other heat-trapping "greenhouse gases" emitted by human activities, such as the burning of fossil fuels.
"This is additional evidence that things look pretty bleak for the polar bear, if current trends continue," said Graham Slater, the lead author of the research.
Polar bears are already losing their habitat as rising Arctic temperatures diminish the sea ice they depend on to hunt for seals. As the ice continues to shrink, polar bears will be forced to seek other food?sources.
The problem for polar bears is they lack the ideal skull strength and tooth size needed for munching plants, grass, tree bark and berries, the scientists said.
Analyzing the biomechanics of their skulls reveals "polar bears would not be able to break up the food as well in their mouths and would not digest it as well," the study said. Seal blubber is softer and requires less chewing, putting less strain on the skull.
Polar bears evolved from the brown bear relatively 掳?recently, and the two are closely related.
The research was based on 3D computer modeling that compared the skull and jaw strength of the two and found polar bears ill-suited to the?tougher chewing demands posed by the largely vegetarian diet of their grizzly cousins.
The findings add to mounting signs of threats to polar bears from global warming that scientists attribute to excessive levels of carbon dioxide and other heat-trapping "greenhouse gases" emitted by human activities, such as the burning of fossil fuels.
"This is additional evidence that things look pretty bleak for the polar bear, if current trends continue," said Graham Slater, the lead author of the research.
Polar bears are already losing their habitat as rising Arctic temperatures diminish the sea ice they depend on to hunt for seals. As the ice continues to shrink, polar bears will be forced to seek other food?sources.
The problem for polar bears is they lack the ideal skull strength and tooth size needed for munching plants, grass, tree bark and berries, the scientists said.
Analyzing the biomechanics of their skulls reveals "polar bears would not be able to break up the food as well in their mouths and would not digest it as well," the study said. Seal blubber is softer and requires less chewing, putting less strain on the skull.
Polar bears evolved from the brown bear relatively 掳?recently, and the two are closely related.
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