Hungry, Hungry Bear Season
By Emily Just
This is a great time of year for food connoisseurs with Thanksgiving on the horizon.
I love to “prepare” for the holiday by eating all things deemed “fall foods” prior to the big meal…pumpkin pie flavored coffee and lattes, apple pie, apple cider, roasts…you get the idea. Unfortunately, my body doesn’t need to prepare for a long nap this winter and I don’t need all those extra calories (hello elliptical machine gathering dust in the basement!).
Lucky for bears, gorging on 15,000 to 20,000 kilocalories (kcal) per day prepares them for their long winter nap. This period of excessive eating and drinking is called “hyperphagia”, which can last several weeks before hibernation. During this period, bears may spend up to 20 hours a day actively feeding on almost anything; like berries, corn, acorns, grass, carrion, and insects. They also drink an excessive amount of water to process large amounts of food and rid the body of nitrogenous waste.
As the fall season progresses, bears eat less and sleep more. At this time, they can often be found lounging near water, so they can continue to drink to purge the body. Even before heading to their dens, they might sleep 22 hours or more a day!
Finally, as their heart rate drops, they move to their dens where they will hibernate for several months. While in this state, they will use up to 4,000 kcal per day (mainly by metabolizing body fat); but do not eat, drink, urinate, or defecate (Watts, et al. 1981). They can reduce oxygen consumption and metabolic rate by half and breathe only once every 45 seconds. Heart rate can periodically drop to 8-21 beats per minute, and blood flow to skeletal muscle (particularly the legs) can be reduced by 45% or more (Folk et al. 1972).
Although we don’t enter a state of hibernation, I still plan on enjoying all the fall foods and “preparing” for winter. I just might have to walk mine off in the woods and hope to not fall asleep near a babbling creek with the bears.
About the author: Emily Just is a Wildlife Ecologist in the Bureau of Forestry, DCNR. She has worked for DCNR for over nine years, holding a B.S. from James Madison University and an M.S. in Applied Ecology and Conservation Biology from Frostburg State University. Emily’s favorite areas of study are biodiversity and applied ecology. Emily resides in Linglestown and enjoys hiking and horseback riding in her spare time. This article was original written for the PA Department of Conservation and Natural Resources Bureau of Forestry e-newsletter, Forest Fridays.
Folk, G. E., M. A. Folk, and J. G. Minor. 1972. Physiological condition of three species of bears in winter dens. Ursus 2: 107-125.
Watts, P. D. et al. 1981. Mammalian hibernation and the oxygen consumption of a denning black bear. Comparative Biochemistry and Physiology A. Comparative Physiology 69:121-123.
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