Study Shows Yellowstone Bears Entering Hibernation Later Than In Past, Emerging Sooner

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American researchers are hoping to embark on a study to find out if climate change is playing a role in grizzly bears heading into the dens later each year and emerging from their winter slumber earlier than ever before. Following more than 20 years of data on collared grizzly bears in the Greater Yellowstone Ecosystem, researchers say they have noticed a troubling trend that could suggest grizzlies are changing their winter hibernation patterns.

There are concerns the fate of grizzlies - considered icons of the wilderness - could become even more tenuous as conflicts with humans would likely increase if this apparent denning phenomenon proves true. Some male bears have been staying out of their dens into the end of December in recent times if food is available and weather permits, while others have ended their winter sleep as early as January.

Researchers there have observed a trend toward later den entry among adult males in recent years, and a corresponding trend of increasing minimum temperatures during November based on data collected from 1975-1999.

"We've got some correlations with temperature and snowfall to suggest they're probably staying out later in the fall because winter is coming later," said renowned U.S. grizzly bear expert Chuck Schwartz. "It appears they are also coming out a bit earlier in the spring as well. There is some timing associated with them coming out earlier, though, because it doesn't behoove a bear to come out of a den before food is available."

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http://www.rockymountainoutlook.ca/portals-code/list.cgi?paper=128&cat=23&id=1188170&more=0