A Long Winter Nap

Published on: Dec. 12, 2011

We just had our first snow of the season. If you're like me, the only thing you wanted to do that day was curl up in bed and sleep. In fact, if we could hibernate all winter long, I bet many of us would. Not only would it do away with the cold-weather blues, it’s also a great weight-loss program, especially after the “holiday gathering poundage” most of us put on. It was during one of these holiday gatherings that I found out something quite shocking. Bears do not hibernate! I was as taken aback as you are right now. How could bears not hibernate? All the bedtime tales I listened to growing up said a bear would sleep all winter long. That’s hibernation isn’t it?

black bear sleeping
Black bear sleeping (NOT hibernating).

Well, just because an animal is sleeping for an extended period of time doesn’t  mean it is hibernating. Instead of hibernating, many enter "aestivation," a form of dormancy in which the animal falls into a deep sleep. When aestivation occurs, the heart rate and body temperatures do not drop sufficiently to qualify as hibernation. Like many species in which this form of dormancy occurs, the animal will sleep a great portion of the summer, or in the bears’ case, the winter, and can be easily awakened. When bears are aroused from this deep sleep, it is not to eat, drink or defecate, but rather to give birth or because they or their habitat was disturbed.  Just like you or I, bears do not like to be disturbed during their winter nap and often awake grumpy, so beware.    

After learning all of this about aestivation, my mind started to wonder about what hibernation actually is and if any Missouri animals actually hibernate. I found out that like aestivation, hibernation is a form of dormancy. There are some Missouri animals that do hibernate, including chipmunks, groundhogs and mice, to name a few. To be considered a true hibernator, an animal must be in a state of inactivity and metabolic depression, with lower body temperatures, slower breathing and lower metabolic rates. For humans it would be like being put under anesthesia. Before they enter this phase, the animals will constantly eat in order to store energy in fat deposits that will help them survive the winter, when their food sources are scarce. They slowly burn their energy reserve during hibernation which causes the slowing of the metabolic rate. This causes the reduction in body temperature and the weight loss of many of the animals. Unlike bears, true hibernators are not easily roused. For example, if one were to pick up one of these hibernating critters they would not wake up. Just don’t forget, you should not disturb wildlife in any situation. It is not uncommon for them, however, to awaken and feed for part of a day when their energy reserves become too low. 

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