Grizzly bear (Ursus arctos) COSEWIC assessment and update update status report: executive summary

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Executive summary

Grizzly Bear
Ursus arctos

Description

Grizzly bears share the typical ursid body form, and are large, muscular, and robust. In contrast to American black bears, grizzlies have a prominent shoulder hump, concave facial profile, and long front claws. Fur colour ranges from blonde through shades of brown to nearly black. Males are, on average, 1.8 times as heavy as females. Typical body mass for adult females ranges from 100 kg for interior populations to 200 kg for coastal bears.


Distribution

Grizzly/brown bears are known or believed to occur in Canada, U.S.A., and at least 42 Eurasian countries. Many Eurasian populations are insular, small, and endangered. World-wide, the brown bear has lost an estimated 50% of its range and abundance since the mid-1800s. The grizzly bear in Canada currently occupies an estimated area of 2 574 000 km2, or about 26% of the country’s land mass. Massive range contraction in North America and Canada has occurred in the post-glacial and historical periods. Today, grizzlies are found in parts of Alberta, British Columbia, Yukon, Northwest Territories, and Nunavut.


Habitat

Grizzly bears are habitat generalists. They can be found from sea level to high-elevation alpine environments. In Canada they occupy habitats as diverse as temperate coastal rain forests and semi-desert Arctic tundra. Most grizzly bears eat primarily vegetation, and their habitat associations are therefore strongly seasonal and typically reflect local plant development. In mountainous regions this may result in seasonal elevational migrations.


General biology

Although they have a carnivore’s feeding and digestive anatomy, grizzly bears are omnivorous and many are primarily herbivorous. In some areas, however, grizzlies are effective predators of moose and caribou, and coastal populations feed heavily on spawning salmon. Female bears usually have their first litters at 6 years of age, litter sizes are 2 or 3, and intervals between litters are commonly 3-4 years. Longevity is around 20 years, although bears as old as 34 have been recorded. Grizzly bears are not territorial, but use home ranges of up to 8000 km2, although in richer environments they use much smaller areas. Grizzlies hibernate for up to 7 months each winter, and cubs are born in the den in January or February.


Population size and trends

The Canadian grizzly population is estimated at between 26 916+ and 29 150+. British Columbia has the largest population, with at least 14 000 bears. About 6000 to 7000 grizzlies live in the Yukon, 5100 live in the Northwest Territories, and 1000 live in Alberta. The population in Nunavut is unknown but is probably between 800 and 2000. Historical numbers in Canada are unknown, but were certainly much higher. However, the population is believed to have been generally stable since 1990.


Limiting factors and threats

There is some natural mortality in bear populations, but most grizzlies die from human activities. Populations in most areas in Canada are hunted, and licenced hunters kill over 450 grizzly bears each year. Another 100 are known to be killed by other human causes, and substantial numbers are killed and not reported.

Incursions into grizzly bear habitat by human activities including mining, forestry, agriculture, residential development, and recreation degrade habitat quality for bears and increase mortality risk. Grizzly bears may be attracted to sites of human activities by potential food. Attraction to garbage and livestock, for example, is responsible for many grizzly bear deaths.

The development of roads and other linear features into grizzly bear habitat is a particular threat. Roads themselves pose little harm, but their use by humans reduces habitat effectiveness in a buffer zone around the roads. In addition, roads provide access for humans with firearms who, legally or illegally, kill bears that would otherwise be less vulnerable.

Human activities have resulted in geographic or genetic isolation of several Canadian grizzly bear populations, including 8 that have been identified in southern BC. Each is small, at fewer than 100 bears, and rescue potential from neighbouring populations is low to nil. The activities that cause isolation also contribute to mortality, so such isolates are at elevated risk of extirpation.


Existing protection

About 8.3% of the range currently occupied by grizzly bears in Canada is classified as “protected”. However, hunting and activities that may degrade habitat quality for grizzly bears are permitted in some “protected” areas. All provinces and territories have restrictions on hunting that include closed seasons, limited-entry permits, harvest quotas, and protection for females and cubs. Bait is not allowed when hunting for grizzly bears, and trade in bear parts is prohibited.

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