Grizzly Bears Benefiting from Climate Change

By Laura Dattaro
Published: October 29, 2013

A female grizzly bear in Yellowstone National Park. A study of the bears in Alberta, Canada has shown that warming temperatures may be good for the bears' health and reproduction. (Karen Bleier/AFP/Getty Images)

Climate change may be making some grizzly bears fatter — and that’s apparently a good thing.

“A simple rule is, the fatter the bear, the better,” Scott Nielsen, a biologist at the University of Alberta, said in a press release. “Certain environments promote fatter bears.”

Those fat-promoting locales may be more prevalent in a warming world. For 10 years, Nielsen led a team that followed 112 bears in the Rocky Mountain region of Alberta, Canada, finding that in years when spring arrived earlier due to warmer temperatures, adult bears had larger bodies and found food more easily. The grizzlies also developed more body fat, which increases the chances that females will successfully reproduce, according to the release.

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The Alberta grizzly is classified as a threatened species by the Alberta government, with about 750 bears living in the province. Only half of those are adults, which can reach up to 800 pounds, according to National Geographic. Though grizzlies tend now to be associated with northern environments, they used to be found as far south as Mexico, and some populations still exist in the Mongolian desert.

“We hypothesize that warmer temperatures in this ecosystem, especially during late winter and spring, may not be such a bad thing for grizzlies,” Nielsen said. “That suggests that species won’t likely be limited by rising temperatures, which would lengthen the growing season and the time needed to fatten prior to hibernation.”

Nielsen's study did not examine hibernation habits of the bears, but, according to Nielsen, warmer weather may not pose a problem for hibernating.

"Grizzly bears just south of Alberta in Montana and probably in the very south ends of Alberta are now denning on the prairies where there is very little snow, so that may not be as limiting as some folks think," Nielsen told "Denning is a response to food shortage, not snow."

The study’s findings are published last month in the journal BMC Ecology.


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