It’s Time to Hibernate!


It’s time to hibernate! In order to survive winter, black bears need to increase increase their body weight by 20-40%!  They do all this by eating mostly vegetables. I
t’s impressive to see just what’s on their grocery list!

The black bears diet is 85% vegetation, but their full diet includes berries, nuts, roots, honey and honey combs, insects, larvae, fish, and some small mammals. To store enough fat from these tasty morsels, a black bear will forage up to 20 hours a day, seeking to consume 20,000 calories a day as winter approaches.

The black bear calendar revolves around hibernation.  There are five distinct phases in the bear year:

First: Black bears have a normal activity level, eating 5,000 to 8,000 calories a day. This is a more relaxed time to be a bear, before things begin to really pick up.

Second: During this phase, bears perform an activity known as hyperphagia, which is when they eat a whole lot more!  This is when bears spend 20 hours a day foraging, getting as fat as they can before they begin hibernation.  These months are also when bears have a greater tendency to run into trouble with people, getting into trash or pet food.

Third: The preparation in the first two phases determines whether a bear will be successful in the coming months. A big shift starts to happen when black bears reach the next phase, when the bear’s body starts transitioning into hibernation. During this time the bears heart rate will slow from 100 beats per minute to just 50. The main activity changes from foraging 20 hours a day to resting 20 hours a day. At this point, the bears consume less food but continue to drink water.

Four: Official hibernation begins. At this point, everything slows down; their heart rate drops down to a nearly undetectable 8-21 beats per minute, and they may only breathe once each minute.

Five: Next is a period called walking hibernation.  It only lasts two or three weeks, and at this point their bodies begin to bounce back to their normal active level. The heart rate starts to climb, pushing its metabolism back to normal levels. This means black bears become hungrier as they awake and reach the beginning of stage one again.

Lisa Wooden

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