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Astounding adaptations of the black bear

By Patt Dorsey

Colorado Parks and Wildlife

Special to The SUN

Bears are bundles of biological bewilderment! Yet, people who clean up after overnight ursine raids on garbage cans may not see it that way. When bears are emboldened to bash birdfeeders and break into houses … well, biology holds no favor with the homeowner.

But while wildlife managers advise thousands of people about black bear conflicts each year, we rarely get to describe why Colorado’s bears are unique and scientifically intriguing or in layman’s terms, “cool.”

For homeowners, understanding bear biology can help protect property and prevent wild bears from becoming “nuisance bears.” Bear biology is also a great

ing, urinating, defecating or exercising. Instead, they survive the winter by converting fat tissues into water and energy.

When people stop eating, we burn fat and muscle. Bears maintain muscle during hibernation, losing less than 30 percent of their muscle strength after 110 days. People who are eating, but confined to bed for 90 days lose 50 percent strength! Astronauts can lose about 10 percent of their strength in just 17 days in space.

Medically, the secrets of black bear hibernation and the hormone-like substances found in hibernating bears may someday help preserve transplant organs, stabilize wounded soldiers, counteract the effects of zero gravity on astronauts or treat arteriosclerosis and reduce heart attacks.

Bear cubs are born in January during hibernation. Amazingly, large female bears give birth to tiny cubs. A female black bear is 200 times heavier than her 12-ounce newborn. This is due in part to her giving birth to premature cubs.

“Preemie” cubs are born nearly naked, with their eyes closed. They weigh and measure the same as a can of soda. They gain weight rapidly, nourished on energetically rich milk. Scientists believe that mystery ingredients in black bear milk might someday increase the survival and growth rates of premature human infants.

Black bears, Colorado’s only bear species, are omnivores. Omnivore comes from Latin omnis, meaning all and vorare, meaning to devour. About 85 percent of a black bear’s diet is plant material. The remaining 15 percent is often, carrion and insects. However, they can and do kill other animals including livestock. In Colorado, their primary foods are grasses, flowers, berries, acorns, beetle larvae and ants.

People, too, are omnivores with a general intestinal tract nearly identical to a bear’s. Consequently black bears are adapted to eating acorns and miller moths, as well as the leftover casserole that migrated to the back of the refrigerator and eventually into the garbage.

Raiding garbage may be a learned behavior, but ironically it is completely natural. Human-food provides a caloric advantage over “natural” foods.

Chokecherries hold about 750 calories per pound and crickets 550. But compare that with our food: a pound of fried chicken, 1,200 calories; the average slice of pepperoni pizza, 290 calories.

The major metabolic advantage of acquiring human-food is the ratio of calories-in to calories-out. Example: lifting a dumpster lid to consume the concentrated calories inside, nets more calories than tearing logs apart to rake out insects.

Bears are noses with legs! Here’s an old saying: “A pine needle fell in the forest. The eagle saw it. The deer heard it. The bear smelled it.” A sense of smell helps bears avoid predators, find mates, cubs and, of course, food.

A bear’s sense of smell is seven times better than a bloodhound and 2,100 times better than ours. Bears can smell animal carcasses from miles away. A bear can smell your trash even when it’s sealed in a plastic bag.

Bears can climb up trees, over fences or onto deck rails. They can roll boulders and carry animal carcasses. So, of course, they can reach a birdfeeder dangling off a deck; and they can break a car window left open a crack to get a French fry under the seat.

Bears are extremely intelligent and have long memories. They can travel over 100 miles away from home, turn and walk a straight line back. They remember how to get to a small patch of oaks where they can find acorns. They also remember that your neighbor leaves trash out overnight.

We have much more to learn about black bears. Future generations will benefit from much of what we learn. Medically or ecologically, black bears are important native, wild animals, without which the wonder and beauty of Colorado’s wild places grows a bit dimmer.

Editors note: Summer bear season is in full swing. Colorado Parks and Wildlife provides this article to help Coloradans to better understand our wild neighbors, and to remind everyone to keep attractants out of the reach of bears.

Dorsey is the area wildlife manager for Colorado Parks and Wildlife in Durango.

This story was posted on September 26, 2012.