Two years ago the Idaho Department of Fish and Game joked about what grizzly bears consider while choosing den sites for the winter:
“The view of course!”
The remark on Facebook was in reference to a spacious den biologists discovered while searching for a 600-pound grizzly bear’s dropped research collar.
The collar’s signal led them to a high-altitude den site that featured a stunning view of the forest and a distant river or lake.
The accompanying images show the view and IDFG Officer Chris Johnson “enjoying the ample head room inside the bear’s den.”
(The bear was not present when the collar was retrieved.)
With another hibernation season close at hand, bears will soon stake out potential den sites or reclaim existing sites.
A sampling of facts about bear dens, courtesy of the National Park Service, referring mainly to bears within the Greater Yellowstone Ecosystem, which includes Yellowstone National Park:
–Den sites are typically located on north-facing slopes at elevations between 6,500 and 10,000 feet. “This is desirable in greater Yellowstone because prevailing southwest winds accumulate snow on the northerly slopes and insulate dens from sub-zero temperatures.”
–Grizzly bears typically excavate dens in 3-7 days, “moving up to a ton of material.” Chamber floors are covered with spruce boughs and forest debris, ensuring air pockets that help trap body heat. Chambers can measure seven feet in diameter.
–Den site openings are typically just large enough for bears to squeeze through. Small openings become snow-covered more quickly and help keep dens insulated.
–Bears typically enter dens for hibernation by mid-November, but male bears can be encountered outside dens well into December. Bears begin to emerge from their dens in February, but female bears with cubs often remain in or near their dens until late May.
–Bears experience a slower metabolism, and lower respiration and heart rates during hibernation. Their breathing, for example, can slow from 6-10 breaths per minute before hibernation to only one breath every 45 seconds during hibernation.
As for the den featured in the images, it was visited by grizzly bear biologist Jeremy Nicholson and IDFG Officers Johnson and Joe Heald. It’s not clear if the den site has been reused.
