Bears tend to build their dens around the time of the first heavy snowfalls in fall or winter. Denali's grizzlies have been observed digging dens as early as August, in response to six-inch snowfalls. Grizzlies don't need to defecate, urinate, eat, or drink during their months-long dormancy, and their body temperature and metabolic rates drop only slightly. The hibernation mechanisms of rodents are vastly different from bears. They rouse themselves periodically throughout the winter, bringing body temperature and heart rates back to normal, perhaps to eliminate body wastes.
Marmots too go into a deep dormancy that is periodically broken.
There's a real sense of being in a subarctic desert which of course it is. It brings home just how tough it is to make a living out there in winter, and how many species have either left or gone into hibernation as an adaptation. All rights reserved.