Wildlife

When Do Bears Hibernate in Yellowstone?

All you need to know about Yellowstone bears and their winter slumber.

Visitors to Yellowstone National Park have an excellent chance of seeing grizzly and black bears most of the year. But Yellowstone’s bears hibernate in the winter so they are hidden from view. Here what you need to know about the seasonal life of bears.

When do Yellowstone Bears Hibernate and For How Long?

Bear with her cubs in a den
Bear with her cubs in a den (Photo: Depositphotos)

Depending on snowfall, temperature and food supply, bears get ready for winter hibernation in late November. The denning period in Yellowstone National Park is approximately 5 months.

Grizzly bears and black bears generally do not eat, drink, defecate, or urinate during hibernation. They live off of a layer of fat which was built-up during summer and autumn. Bears maintain a body temperature close to normal during hibernation which lets them react to danger and sources of food faster than many other hibernating animals.

 

In Springtime, Bears Emerge From Their Dens

Grizzly Bear near Yellowstone's Obsidian Creek on April 24, 2009
Grizzly Bear near Obsidian Creek on April 24, 2009 (Photo: NPS/Jim Peaco)

Grizzly Bears

Male grizzlies come out of hibernation in mid to late March. Females with cubs emerge later, in April to early May. After an unseasonably warm winter, bears may come out of hibernation as early as January or February.

Black Bears

Black bears den in lower elevations and therefore wake earlier, typically in late February.Sometimes, if there is a warm winter and food is available, the bears might emerge out of their dens to eat.

Breakfast

When bears come out of hibernation, they look for easy food sources. Often, the quick meal is a carcass of an animal that has died during the winter (winter-kill), namely elk and bison. Later in the Spring, young new-born elk and bison calves become the meal of choice.

It is a bit of a myth that bears awake super hungry. Kerry Gunther, who leads Yellowstone’s bear management program told the Yellowstone Forever Institute, “When they first come out they don’t eat that much, and they are lethargic. For a week or two they spend more time sleeping on the carcass than eating it. Their metabolisms are not totally kicked in–they are in a kind of walking hibernation.”

Learn more about What Yellowstone Bears Eat

Keep a Safe Distance from Bears

It’s very important to remember that bears are dangerous animals. Bears have killed people in the park, so if you do see a bear from the road, make sure you remain in your car as you observe the animal from a safe distance.