Preparing for Sleep
Bears prepare for their winter slumber all summer. They begin eating in May and don't stop until August. They store fat in various places around their body to be used while they hibernate. Female bears must eat a lot of extra food because they give birth during their winter sleep and will need to feed their cubs.
Finding a Location
When a bear's instinct tells it to prepare for hibernation, it goes out looking for a good place to sleep. Most people picture bears sleeping in caves, but they sleep anywhere that looks good to them, even under a house. Bears have been known to hibernate in the side of a hill, in a pile of leaves, in places where rocks have formed a shelter, and even in cornfields. The bear determines its location in September.
When bears hibernate, their breathing and heart rate slow down a little, whereas other animals in hibernation have systems that drop drastically. Bears' body temperatures also only drop a few degrees where normal hibernators drop at least 30 degrees. Bears do not wake up to go to the bathroom or eat as other hibernators do. They sleep from September to April. Female bears may give birth, clean off their cubs and then go back to sleep, leaving the cubs to nurse.
As the temperature warms and the flowers emerge, the bears wake up. There is no explanation as to how the bears know when to wake up other than their bodies sense spring by the feel and scents in the air. After the bears wake up, they begin the cycle all over again. They start searching for food and eat until it is time to hibernate again.