 |
NWT
Grizzly Bear
Ursus
arctos horribilis
Description
Grizzly
bears, sometimes called brown bears, range in colour from dark brown to
blonde. The white tipped
hairs around their face and shoulders give them their grizzled appearance.
A grizzly can be distinguished from a black bear by the hump on its
shoulders and its more pronounced brow ridge.
Adult male grizzly bears average 1.8 m from nose to tail and can
weigh up to 250-300 kg. Females
are smaller and weigh between 95-170 kg.
Distribution
 |
Historically,
North American grizzly bears ranged from Hudson Bay to the West
Coast and from the Arctic Ocean to California and Mexico. Grizzly
bears were eliminated from the prairies following European
settlement. Grizzlies now occur in northern Canada, through Alaska,
the Rocky Mountains and in small pockets in Washington, Montana,
Wyoming and Idaho. Grizzly bears occur through much of the NWT,
particularly north of the treeline and throughout the Mackenzie
Mountains. |
NOTE: Click on map for full view.
Distributions are approximate and not intended for legal use.
(JPG
= 2026 KB)
|
Population Size and Trends
There
were probably more than 100,000 grizzly bears in North America prior to
European settlement. Since
then, the population in the continental United States has dwindled to
about 1,000 grizzly bears. In
Canada, the population has decreased to 20,000-25,000 grizzly bears that
live in several distinct populations.
Currently, most grizzly bear populations in North America are
thought to be stable. The NWT
is home to an estimated 3,500-4,000 grizzly bears.
The highest concentrations of grizzly bears in the NWT are found in
the Mackenzie Mountains.
Habitat
Grizzly
bears in the NWT occur primarily in open alpine or tundra habitats, but
they can also be found in forested areas.
They have large home ranges relative to most other bear species.
On average, a male’s range can extend over 2000 km2
while a female’s range is about half that size.
Grizzly bears found on the central barrens seem to need even larger
home ranges. Research has
shown that grizzly bears on the tundra use a home range of up to 6700 km2
for males and 2100 km2 for females.
Grizzlies require an adequate food supply, proper denning sites and
protection from human disturbances.
Biology
It
takes a long time before grizzly bears are old enough to reproduce.
Females have their first cubs between six to nine years of age with
subsequent litters every three to four years.
Mating occurs in June/July. Cubs
are born in the den between mid-January and mid-March.
On average, two cubs are born in a litter.
Cubs stay with their mothers for two or three years. Females
generally only produce four to five litters in their lifetime.
Males take no part in raising the cubs.
In fact, it is not uncommon for male grizzly bears to kill cubs.
Grizzly
bears eat all kinds of food. One
study has suggested that plants (horsetails, berries, legume roots and
grasses) make up about 90 per cent of the diet of grizzly bears in the
Mackenzie Mountains. In the
central barrens, caribou, various berry species, grasses and sedges are
important parts of the diet. Grizzly
bears are not true hibernators since their body temperature does not fall
much below normal during their winter sleep. Grizzly bears generally den in holes they dig in the ground.
Natural rock caves can also be used.
Pregnant female bears are generally the first to enter dens around
late September. Some adult
males may not den until the onset of winter.
Males are the first to emerge in spring.
Some females do not leave their dens until late May.
Limiting Factors
Biological
limiting factors for NWT grizzly bears are thought to be adult female
survival and low reproductive output.
Human activities can affect grizzly bear populations through
harvesting, habitat degradation or both.
As mineral and energy exploration, outfitting camps and road
developments increase in the NWT, contact between humans and bears is
rising. Unfortunately,
contact sometimes results in bears being destroyed or displaced from
important habitat. Bears tend
to avoid humans when possible.
This avoidance may cause the bears to abandon large sections of their home
range if it is undergoing exploration or development.
Protection
COSEWIC
designated all existing grizzly bear populations in Canada as Vulnerable
in 1991 because of the potential for degradation and loss of grizzly
bear habitat. Two Canadian
populations have been declared extirpated by
COSEWIC.
In the NWT, it is illegal for non-Aboriginal people to harvest
grizzly bears except in the Mackenzie Mountains and the Inuvialuit
Settlement Region. The
Mackenzie Mountain harvest is open only to resident hunters, with a limit
of one bear per hunter’s lifetime.
The Inuvialuit Settlement Region has a quota of 20 bears per year
that is distributed to local Hunters’ and Trappers’ Associations.
It is illegal for anyone to kill denning bears or bears with cubs.
Recovery
A
co-management plan for 1998-2002 is being implemented for grizzly bears in
the Inuvialuit Settlement Region. Initiatives
under this plan include raising public awareness of grizzly bears and
their biology and gathering new information on the bears.
During the last five years, biologists have conducted extensive
radio collar studies to learn more about the movements, feeding behaviour
and den site requirements of grizzly bears on the central barrens.
Research will continue during the next five years with a mark and
recapture study to provide a more accurate population estimate for the
central barrens. In the
Inuvik Region, hunters are providing traditional knowledge about grizzly
bears that will help direct future research. All this information will help guide the development of
effective co-management policies on the harvest and protection of grizzly
bears in the NWT.
|