Why do bears hibernate? It would be as easy to ask why do birds fly south in the fall or salmon go back to the rivers where they hatched to lay their eggs? It is all part of the cycle of nature and the way each animal adapts to the changing season. Bears hibernate because it is the only way they can survive the long cold winters that occur in the northern hemisphere. Depending on one’s preference it is either the way God made them or the way they evolved for their surroundings.
Bears have short, compact bodies and large appetites. This means that they don’t migrate well and, when not sleeping, tend to eat a lot. Winter is a problem. The grubs, fruits and berries that they need to survive are no longer available, so the bear compensates by hibernating. It eats a lot during the summer and fall, putting on body fat to create supplies for sleeping and then finds a cozy, secluded cave, and curls up for a long winter’s nap. What’s amazing isn’t why the bear hibernates, but how it hibernates and what happens during hibernation!
The hormones of the bear kick in due to decreasing light and temperature. This confuses the bear so it looks for a safe place to hide. Once it finds a den, the bear’s heart rate and metabolism slows Its nervous system goes down to a near comatose stage and the bear’s body basically shuts down. This is why the bear needs a small cave in which to hibernate. The bear is so deep asleep that it can be easily killed by other animals or even exposure to the elements.
What is even more amazing, female bears give birth during hibernation, not waking up until the cubs are several months old and capable of fending for themselves to a certain extent! There are a lot of women that would like to be a bear (Think about it, ladies. No shaving of legs, no pain during child birth, sleeping through the baby stage and only dealing with males for occasional sex. All this plus you go to bed fat and wake up thin)!
Bears hibernate due to the hormonal changes from decreased light and temperature. What is interesting is that once in a cave hibernating the light and temperature becomes steady, so how does the bear know to stop hibernating? It is probably a survival mechanism that kicks in when body reserves get to low, the bear gets hungry.
Of course sleep of the female bears it is probably the teenage cubs getting a bit rude and loud, it usually is with humans! Ah, the cycle of nature.