When winter comes, some animals have a special way of surviving the cold and finding food. Animals like ground squirrels, bats, and hedgehogs go into a deep sleep called hibernation. During hibernation, their bodies get super cold, almost as cold as the outside, and their hearts beat very, very slowly. This helps them use very little energy, so they can live off their body fat for months without needing food. Even though they’re in a deep sleep, they wake up every now and then to warm up and stretch a little, which keeps their muscles from getting too weak.
Bears, though, don’t go into a full hibernation like squirrels or bats. Instead, they enter a lighter kind of winter sleep called torpor. In torpor, a bear’s body temperature only drops a little, and its heart rate slows down but not as much as in true hibernation. This way, bears can still wake up quickly if they sense danger, like a loud noise near their den. During torpor, bears don’t eat, drink, or even go to the bathroom for months! Their bodies actually recycle waste to stay healthy, which helps them keep their muscles strong. Mother bears can even give birth to tiny cubs during this time and keep them warm and fed.
This special way of resting helps bears wake up in the spring without losing too much strength, even though they use up most of their stored energy during the winter. Bears get ready for this by eating a lot in the fall, so they have enough energy to sleep through the cold months. While they sleep, their bodies use this stored energy, which helps them stay strong and ready to be active again when food is available. Bears’ winter rest shows how animals have developed different ways to survive the cold months, with a unique balance of rest and being ready for action.