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Nature Notebook – Bear Hibernation

Southwest Michigan’s bear should be in his “fall transition” stage of hibernation preparation. He will be cutting back the amount of food he eats but will continue to drink…a lot. His body still needs large amounts of water to process the 15,000 to 20,000 calories he was consuming each day for the last month and a half.

His body will prepare for the long sleep by resting for 22 hours each day. Any leafy, shallow spot in the forest will serve as a bed at this time. His heart rate will drop by 50 percent. Once the bear enters his den (in December), the heart rate will drop to only 8 to 21 beats per minute.

Hopefully our bear consumed enough food this summer to pack on sufficient fat to survive the long torpor period of winter. His body will need to metabolize up to 4,000 calories each day from those reserves to keep vital body processes going. Although these processes have slowed to a minimum, the body size of a bear necessitates a substantial amount of energy just to maintain them. Fortunately, the bear’s extraordinary ability to turn toxins into muscle proteins eliminates a potentially large withdrawal from the fat “bank” to keep his muscles from wasting away.