NWT Grizzly Bear (Ursus arctos) - Northwestern population

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Species at Risk (NWT) Act list: No status
Federal Species at Risk Act list: No status
COSEWIC Assessment: Special Concern 
NWT General Status Rank: Sensitive                  

Description

Grizzly bears, sometimes called brown bears, have long shaggy coats with coarse guard hairs overlying a dense mat of underfur. Around the shoulders the hair lengthens to form a ruff. Colour varies from light gold to almost black, with pale or blonde bears being the most common on the barren-lands. 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. In the NWT, adult male grizzly bears can 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

There are two subspecies of grizzly bear in North America. The coastal brown bear or Kodiak bear (Ursus arctos middendorffi) is found on the islands and south coast of Alaska.

Grizzlies in the NWT, are divided into four distinct populations, based on the ecosystems they inhabit. Arctic coastal grizzlies occupy the area between Inuvik and Coppermine, and are particularly abundant on Richards Island west of the Tuktoyaktuk Peninsula. Arctic mountain grizzlies are found primarily in the northern Yukon from the Alaska border to the Richardson Mountains, which overlap the north-western part of the NWT. The northern interior population ranges throughout northern British Columbia, most of the Yukon, and extends into the southern Mackenzie District. The fourth classification is the barren-ground grizzly, which occurs over the northern and eastern Mackenzie District, and the central portion of the Keewatin District. On all parts of their range, grizzlies prefer open or semi-forested areas. They are most common in alpine and subalpine terrain, or on the tundra, but sightings in the boreal forest are not unusual.

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.

Reproduction

Grizzly bears usually become sexually mature between 5 and 7 years of age. The age of maturity is dependent on habitat quality and the corresponding vitality of the bears. In the Mackenzie Mountains, the quality of forage is low and although some bears reproduce between 6 and 10 years of age, they do not reach peak reproductive potential until 10 to 16 years. Females continue to produce cubs until their late teens and early 20’s.

The oldest recorded age for a female to give birth is 25 years. However, even though grizzly bears are potentially long-lived, a long inter-litter period of approximately 3 years and the small litter size (average 2 cubs) means that they are not particularly prolific. Under the best possible conditions, a female, living to age 25, could experience six reproductive cycles and produce about 13 cubs.

Male and female grizzlies are polygamous and mating occurs from late spring until early summer. "Delayed implantation," however, ensures that the fertilized egg does not implant in the uterus until October or November. This is believed to be a survival mechanism in that the embryo will not develop unless the bear is healthy and has sufficient fat reserves to last the winter and to look after the cubs. Delayed implantation and the corresponding brief period of development (6 – 8 weeks) means that the cubs are surprisingly tiny at birth.

Grizzly bear cubs are born in January or February while the female is still in her den. Most litters contain two cubs, but one, three, or even four is possible. The cubs are about the size of a small squirrel, and weigh between 350 – 700 g. They are blind and hairless. Their total helplessness at birth is ideally suited to the lethargic, fasting mother bear who is in not condition to feed and cope with more advanced offspring. The cubs grow rapidly and weigh 15 kg at 3 months and 25 kg at 6 months, but some nurse until they are almost 2 years old. The cubs remain with their mother for at least their first year. They are highly dependent on her for protection from all dangers, including large male bears which occasionally kill and eat cubs. The mother spends much time teaching the cubs hunting and feeding techniques. They also learn to recognize predators and to locate suitable denning areas. The mother is a strict disciplinarian and quickly discourages misbehaviour with a sharp blow from her forepaw. The cubs den with their mother for a second winter and then are chased off in the spring when she goes into oestrus. If for some reason the mother does not go into oestrus, the family may den together for the third winter.  The first year of independence for the cubs is difficult. Without the solicitous attention of the mother, they seek out their own home range and denning site. Females often use a portion of the mother’s home range, while males travel farther afield to establish a new territory.

Diet

Grizzly bears in the NWT 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. They also eat a great many lemmings and ground squirrels, which they excavate from burrows. Grizzlies are opportunistic predators and will kill moose, muskoxen and sheep if the occasion arises. Grizzlies are also carrion eaters and the carcasses of winter-killed animals may also provide a source of food in spring before vegetation is available.

Another favourite food of grizzly bears is garbage. In southern parks, grizzlies are well-known for congregating at dumps. This has not been a problem in the NWT, though as many as six grizzlies have been seen at the dump in Tungsten. Grizzlies also appear occasionally at fishing camps and remote industrial sites, where they are sometimes shot in defense of life or property.

Harvest Levels

Grizzly bears in the NWT are classified as a big game species and a furbearer.

Big Game Species

Currently in the NWT, grizzly bears are managed mostly by controlling the hunting season for resident and non-resident hunters. 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. General Hunting Licence holders (including all aboriginal, most Metis and a few long-time non-aboriginal residents) may hunt during any season.

Management

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. As industrial development proceeds, the need for comprehensive studies on grizzly bears is being recognized. The real problem however is often people, not bears. What most people in bear country fail to realize is that they are in an area where man is not supreme. Bears are more powerful than people, operate by a code that does not recognize private property, and are impelled by an appetite less discriminating than ours. People in bear country must therefore be prepared to make concessions to their ursine neighbours, and remember to show them the respect they deserve.