The grizzly bear (
Ursus arctos horribilis) is a
subspecies of the brown bear. At one time there were an
estimated 50,000 grizzlies in North America. They once were
found from the Mississippi River to the coast of California,
from Mexico to Canada, but grizzlies now occupy less than 2% of
that range. In the United States, where grizzlies are found in
Alaska, Idaho, Montana, Washington, and Wyoming, they are
listed as threatened under the Endangered Species Act. Fewer
than 1,100 grizzly bears can be found in the continental United
States.
Grizzlies are highly adaptable to various habitat types:
they can flourish in forests, mountains, prairies, wetlands,
and even along the shore. They will dig beds in shady spots in
which to sit out the heat of the day. They hibernate in the
winter when food is scarce, living off stored body fat, which
not only supplies energy but also keeps them warm.
However, most parts of the historic U.S. grizzly range no
longer contain sufficient contiguous habitat to support a
viable grizzly population. The Yellowstone area holds the most
promise, but even here an important food source, the whitebark
pine, is expected to be completely lost because of exotic
disease and/or global climate change.
The grizzly diet consists mostly of insects, roots, nuts,
berries, rodents, and carrion. They are great diggers, using
their powerful paws and claws to pull up roots and bulbs. When
catching rodents, grizzlies are surprisingly swift—over short
distances. Grizzlies occasionally prey on larger animals,
sometimes even bison. Although grizzlies (particularly cubs)
can be killed by other large mammals (such as wolves and
mountain lions) their only habitual predator is man; most
grizzly deaths in the United States, from the mid 1800s to the
present, have been caused by humans.
It isn't always easy to distinguish a grizzly bear from a
brown or black bear (it's better to check the ears, which on a
grizzly are round and smaller). A grizzly's coat can be any
shade from black to blond, though it's usually brown. The name
"grizzly" was inspired by light tips on the fur of the bear's
head and shoulders. Grizzlies are heavier than black bears,
though: the males average 500 lbs; and the females average 375
lbs. When on all fours, grizzlies stand between 3.5 and 4 feet;
when standing upright, they reach 6 to 7 feet.
Cubs, who weigh about a pound at birth, stay with their
mothers for about two and a half years, during which time they
are carefully protected. Usually in litters of two or three,
the cubs will follow their mother, learning what to eat and
where to find it. If danger approaches, it isn't uncommon for a
mother bear to shoo her cubs up a tree for protection. Once the
cubs have matured, they leave their mother to fend for
themselves. With a span of approximately three years between
litters, grizzlies are considered among the slowest reproducing
mammals in North America. In the wild, grizzlies live 20 to 30
years.
