Each year at Thanksgiving, I vow to not over-indulge on stuffing, gravy, green-bean casserole and pie and to not end up lying melted into the couch watching the Dallas Cowboys lose to, well, whomever they’re playing. And, every year I fail. I doubt I’m alone in good intentions losing out to the short-lived bliss of caloric-intake overload.
This time of year, black bears don’t share our concerns about over-indulgence. In late summer, a biological switch turns on and they become eating machines, solely focused on adding fat in preparation for a food-less hibernation.
Research has shown that during the course of a year black bears pass through four distinct physiological and biochemical stages; hibernation (no food or water), walking hibernation (when food intake is below normal levels), normal activity (spring and summer food intake) and hyperphagia.
Bears come out of hibernation in the spring having lost 20 percent to 40 percent of their body weight. They will feed on soft mast – grasses, forbs and other vegetation – at this time and are consuming around 2,000 calories a day. Black bears are opportunistic omnivores, and although 90 percent of their diet is comprised of vegetation, they seek ants and larvae, bird and bee nests and kill elk calves and feed on carrion. Their spring and summer diet allows for weight gain, but it does not provide them with enough fat to survive the long winter months without food.
Hence, in late summer bears enter a feeding-frenzy phase, otherwise known as hyperphagia, which is defined as compulsive overeating over a prolonged period. The term is derived from the Greek words for “eating or devouring” and “very much or many.”
At this time, bears become gluttons, seeking hard mast foods such as berries and acorns to build ample fat reserves to live off of during hibernation. “Devouring very much” is fitting as bears are daily feeding for 20 hours, eating 20 to 30 pounds of hard mast, adding three to five pounds of fat and consuming around 20,000 calories. Calorie-wise, that amount is equivalent to 30 Burger King Whoppers!
An interesting aspect of bears and hyperphagia is how they can quickly add so much fat and weight and, unlike us, be spared adverse health consequences. Research looking into what bears do while hibernating is leading to medical advances in the areas of heart disease, diabetes, high-cholesterol and more.
All this, of course, assumes good natural food conditions, which has fortunately been the case the last two local bear seasons, reflected in lower numbers of sightings and conflict. Bears that have become food-conditioned trade in their natural wariness of people to obtain abundant and high-calorie people food, but in years of quality natural food production, that should be the exception and not the norm.
Most bears want to be out in the wilds where they belong, feeding as gluttonous, wild bears should. One can only hope for continued cooperation with the weather providing conditions for good natural food production and in residents not feeding bears.
bp@frontier.net. Bryan Peterson is director of Bear Smart Durango, formed in 2003 to educate residents about coexisting with bears and reducing the amount of human food available to bears. Visit www.bearsmartdurango.org.
