Bears

Bears have the distinction of being the world’s largest terrestrial carnivores. Worldwide, there are eight bear species, three of which can be found in North America, and two of which make their home in the Province of Alberta.

Classification

Bears are mammals classified under the family Ursidae. The two bear species that live in Alberta are the black bear (Ursus americanus) and the grizzly bear (Ursus arctos horribilis, a subspecies of brown bear, Ursus arctos).

Characteristics

Some general distinguishing traits of bears include:

  • Large stocky body covered with thick shaggy hair
  • A long snout
  • Powerful forelegs
  • A short tail
  • A plantigrade walk; bears walk on the heels of their feet
  • Non-retractile claws

Food and the Food Chain

Both black and grizzly bears are omnivorous, having diets that include both plants and animals. Both bears typically forage for their food, and will eat carrion if it is available. They will also hunt for a meal, and may take invertebrates, fish, rodents, and the calves of larger animals like moose.

Both species have a relatively unspecialized digestive system, which is essentially a carnivore's gut that has been lengthened. They have difficulty digesting the woody parts of plants, but both species can still survive on a very high proportion of plant foods in their diet. They choose food items that are easy to digest and counterbalance low digestibility by large intake.

Reproduction

When breeding, both black and grizzly bears have the ability to delay implantation of the embryo, with the result that young are born and nursed by the mother while she is sleeping in her winter den.

Hibernation

Both black and grizzly bears become dormant in the winter months as a means of avoiding the harsh climate and short food supply.

Black bears spend about five or six months in their winter dens in a state of hibernation. In this state, the black bear's body temperature and metabolism drop, and it does not eat, drink, or excrete anything until it awakes the following spring.

Grizzly bears also spend the winter in a mostly dormant state, though they do not do so for the same long duration as black bears, and they will periodically wake and roam close to their winter den.

 

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Updated: Jun 22, 2009