JACKSON, Wyo. — It’s that time of year again, when the grizzly and black bears are getting ready to go into what many people call hibernation. But, according to Grand Teton National Park (GTNP), it’s not a true hibernation.
GTNP Foundation writes on its website that most black bears have entered their winter dens by the end of October, with most grizzly bears entering their winter dens during the month of November. GTNP confirms that this behavior is an adaptation to survive the harsh winter.
However, in a past social media post, GTNP emphasized that the black and grizzly bears of the Greater Yellowstone Ecosystem (GYE) are not going into a full hibernation, defined as a constant and uninterrupted slumber for months at a time.
Instead, GYE bears are entering a state called “torpor,” which GTNP defines as a state of lowered physiological activity where a bear’s body temperature will drop approximately 12 degrees (from their usual core temperature around 100°F). During this time, they only need one breath every 45 seconds (compared to a usual 15 to 20 breaths per minute) and they don’t need to eat, drink, urinate or defecate.
These bears also can and do occasionally wake up and even leave their dens.
GTNP writes that hibernation is one of three main strategies that GYE wildlife use to survive. The other two are migration, like the pronghorn, and adaptation, like moose.
This story runs annually.
