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Bear Hibernation and Reemergence in Yellowstone

When do the Yellowstone bears hibernate and when do they wake and come out of their dens? See photos and watch a video.

Visitors to Yellowstone National Park has an excellent chance of seeing grizzly and black bears. Bears are seen many places in the park such as the Lamar Valley. Since bears hibernate in the winter, and much of the park’s best bear habitat has seasonal closures to protect both bears and humans, make sure you are familiar with the regulations before embarking into the backcountry in search of a bear observation.

When do Yellowstone Bears Hibernate and For How Long?

Grizzly bear in the canyon area on Nove 20, 2014
Grizzly bear in the canyon area on Nov 20, 2014. NPS/Neal Herbert

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.

Video of a Grizzly Bear in Hibernation

Transcript – Christmas in Yellowstone: “High in the fiercest peaks, there’s a small retreat that winter will never reach – the den of a grizzly bear. The bear is not asleep. Since November, she’s been in a state of hibernation. Her heart beats a third of its normal rate. She breathes less than twice a minute. She won’t eat or drink for up to five months. She won’t urinate or defecate. She’ll recycle her own waste into protein, losing weight yet building muscle, all while barely moving. Safe from cold and hunger, she has mastered the winter wilderness.”

In Springtime, Bears Emerge From Their Dens

Grizzly Bear near Obsidian Creek on April 24, 2009
Grizzly Bear near Obsidian Creek on April 24, 2009NPS/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.


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.