Outdoors 10 unexpected facts about bear hibernation By Sara Laux Published: November 30, 2018 Updated: March 26, 2024 share Share on Facebook Share on Twitter Share on Pinterest Copy Link Cancel View in Fullscreen 1 2 3 4 5 6 7 8 9 10 11 12 Photo by Luca Pape/Shutterstock 10 unexpected facts about bear hibernation While most of us feel like waiting out the chilly winter under a big, fluffy duvet, bears’ hibernation takes cold-weather sleep to a whole new level. Here are some cool facts you may not have known. View in Fullscreen 1 2 3 4 5 6 7 8 9 10 11 12 Photo by Sergey Uryadnikov/Shutterstock Only pregnant polar bears hibernate While both male and female brown and black bears hibernate, only pregnant polar bears den up for the winter. View in Fullscreen 1 2 3 4 5 6 7 8 9 10 11 12 Photo by Erik Mandre/Shutterstock Bears act a little funny once they wake up Bears stay in a state of "waking hibernation" for several weeks after they wake up. They may act like they're drunk, or really, really tired. View in Fullscreen 1 2 3 4 5 6 7 8 9 10 11 12 Photo by Alexey Suloev/Shutterstock Bears burn up to 4,000 calories a day while hibernating Bears fatten up a lot before going into hibernation. In fact, a hibernating adult male may have more than a million calories stored. View in Fullscreen 1 2 3 4 5 6 7 8 9 10 11 12 Photo by Susan Kehoe/Shutterstock Hibernating bear mamas wake up to give birth Bears sleep all winter — but pregnant females will wake up to give birth. If she hasn't stored up enough energy, though, she won't have cubs that year. View in Fullscreen 1 2 3 4 5 6 7 8 9 10 11 12 Photo by CherylRamalho/ Shutterstock Bears don't hibernate because of the cold Bears can handle the cold, but they can't survive without food. Because food is scarce in the winter, they hibernate instead. In places where food is available during the winter, bears won't hibernate. View in Fullscreen 1 2 3 4 5 6 7 8 9 10 11 12 Photo by Raj Krish/Shutterstock Bears' winter sleep isn't "true" hibernation Unlike rodents, who face the risk of freezing to death during the winter, bears' body temperatures go down less than 10 degrees. View in Fullscreen 1 2 3 4 5 6 7 8 9 10 11 12 Photo by Bildagentur Zoonar GmbH/Shutterstock Bears' heart rates slow waaaaay down During hibernation, a bear's heart rate goes from 50 to 10 beats per minute. View in Fullscreen 1 2 3 4 5 6 7 8 9 10 11 12 Photo by Susan Kehoe/Shutterstock Bears don't wake up during hibernation (even to go to the bathroom) During hibernation, a bear re-absorbs its feces and urine — so it never needs to get up to pee in the middle of the night. View in Fullscreen 1 2 3 4 5 6 7 8 9 10 11 12 Photo by Sergey Uryadnikov Bears lose a lot of weight while hibernating Bears lose between 25 and 40 per cent of their body weight while they sleep the winter away. View in Fullscreen 1 2 3 4 5 6 7 8 9 10 11 12 Photo by theskaman306/ Shutterstock Bears grow new paw pads while they sleep A bear will lose its paw pads during hibernation, and new ones will grow. View in Fullscreen Related galleries Attention, leaf peepers! Here are 9 of the best trees for vibrant fall colours Meet 12 of the hardest working critters in cottage country 5 old-timey (and completely absurd) beliefs about wildlife 1 2 3 4 5 6 7 8 9 10 11 12 10 unexpected facts about bear hibernation While most of us feel like waiting out the chilly winter under a big, fluffy duvet, bears’ hibernation takes cold-weather sleep to a whole new level. Here are some cool facts you may not have known. Related Story 10 surprising ways Canadian animals handle cold weather