grizzly

　 　

WordNet

1. powerful brownish-yellow bear of the uplands of western North America (同)grizzly_bear, silvertip, silver-tip, Ursus horribilis, Ursus arctos horribilis

PrepTutorEJDIC

1. 灰色の / しらが混じりの / =grizzly bear

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/03/13 17:09:12」(JST)

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For the dance, see Grizzly Bear (dance).

For other uses, see Grizzly (disambiguation).

Grizzly bear
Conservation status
Endangered (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Carnivora
Family:	Ursidae
Genus:	Ursus
Species:	U. arctos ssp.
Binomial name
Ursus arctos (Linnaeus, 1758)
Subspecies
U. a. horribilis U. a. middendorffi U. a. gyas
Shrinking range.

The grizzly bear (Ursus arctos ssp.) is any North American subspecies of the brown bear, such as the mainland grizzly (U. a. horribilis), the Kodiak (U. a. middendorffi), the peninsular grizzly (U. a. gyas) and the recently extinct California grizzly (U. a. californicus). Specialists sometimes call the grizzly the North American brown bear because the grizzly and the brown bear are one species on two continents. In some places, some may nickname the grizzly the silvertip for the silvery, grizzly sheen in its fur.

Since the mainland grizzly is so widespread, it is representative and archetypal for the whole subspecific group. Even so, classification is being revised along genetic lines. Its closest relatives are the European cave bear and the polar bear.

Except for females with cubs, grizzlies are normally solitary, active animals, but in coastal areas, grizzlies gather around streams, lakes, rivers, and ponds during the salmon spawn. Every other year, females (sows) produce one to four young (usually two) which are small and weigh only about 500 grams (1 lb). A sow is protective of her offspring and will attack if she thinks she or her cubs are threatened.

Classification

Meaning of "grizzly"

The word "grizzly" means "grizzled;" that is, golden and grey tips of the hair. This is not to be confused with the word "grisly". Nonetheless, after careful study, naturalist George Ord formally classified the California grizzly in 1815—not for its hair, but for its character—Ursus horribilis. Thus Ord made a famous pun. Indeed there were many accounts of grizzlies fighting and beating longhorn bulls.

Genetics

From 1815 on, grizzlies were classified in a species separate from all other bears. However, after modern genetic testing, the grizzly joined the brown bear (U. arctos). So in Eurasia, it is the "brown bear;" in North America, it is the "grizzly." In other words, the grizzly and the brown bear are one species on two continents. Currently, Rausch and others classify three subspecies of the new "North American brown bear:" U. a. horribilis, middendorffi, and gyas. But more recent studies of mtDNA suggest that this three-fold division of living grizzlies needs revision. Further testing of Y-chromosomes is required to yield an accurate new taxonomy with different subspecies.

Appearance

Most adult female grizzlies weigh 130–200 kg (290–440 lb), while adult males weigh on average 180–360 kg (400–790 lb). The average total length in this subspecies is 198 cm (6.50 ft), with an average shoulder height of 102 cm (3.35 ft) and hindfoot length of 28 cm (11 in). Newborn bears may weigh less than 500 grams (1.1 lb). In the Yukon River area, mature female grizzlies can weigh as little as 100 kg (220 lb). One study found that the average weight for an inland male grizzly was around 270 kg (600 lb) and the average weight for a coastal male was around 408 kg (900 lb). For a female, these average weights would be 136 kg (300 lb) inland and 227 kg (500 lb) coastal, respectively. On the other hand, an occasional huge male grizzly has been recorded which greatly exceeds ordinary size, with weights reported up to 680 kg (1,500 lb). A large coastal male of this size may stand up to 3 m (10 feet) tall on its hind legs and be up to 5 ft (1.5 m) at the shoulder. Although variable from blond to nearly black, grizzly bear fur is typically brown in color with white tips. A pronounced hump appears on their shoulders; the hump is a good way to distinguish a black bear from a grizzly bear, as black bears do not have this hump.

Range and population

Brown bears are found in Asia, Europe, and North America giving them one of the widest ranges of bear species. The ancestors of the grizzly bear originated in Eurasia and traveled to North America approximately 50,000 years ago. This is a very recent event, on an evolutionary timescale, causing the North American grizzly bear to be very similar to the brown bears inhabiting Europe and Asia.

In North America, grizzly bears previously ranged from Alaska to Mexico and as far east as the western shores of Hudson Bay. In North America, the species is now found only in Alaska, south through much of western Canada, and into portions of the northwestern United States including Idaho, Montana, Washington and Wyoming, extending as far south as Yellowstone and Grand Teton National Parks, but is most commonly found in Canada. Only about 1,500 grizzlies are left in the lower 48 states of the US. Of these, about 800 live in Montana. About 600 more live in Wyoming, in the Yellowstone-Teton area. There are an estimated 70–100 grizzly bears living in northern and eastern Idaho, the North Cascades ecosystem of northern Washington, and may begin repopulating in Colorado, although there has been no confirmed sighting of a grizzly in that state since 1979.

In September 2007, a hunter produced evidence of grizzly bears returning to the Selway-Bitterroot Wilderness ecosystem, in Idaho and western Montana, by killing a male grizzly bear.

Its original range also included much of the Great Plains and the southwestern states, but it has been extirpated in most of those areas. In Canada, there are approximately 25,000 grizzly bears occupying British Columbia, Alberta, the Yukon, the Northwest Territories, Nunavut, Ontario and the northern part of Manitoba. Combining Canada and the United States, grizzly bears inhabit approximately half the area of their historical range. In British Columbia, grizzly bears inhabit approximately 90% of their original territory. There were approximately 25,000 grizzly bears in British Columbia when the European settlers arrived. However, population size significantly decreased due to hunting and habitat loss. In 2008, it was estimated there were 16,014 grizzly bears. Population estimates for British Columbia are based on hair-snagging, DNA-based inventories, mark-recapture and a refined multiple regression model. The Alaskan population of 30,000 individuals is the highest population of any province/state in North America. Populations in Alaska are densest along the coast, where food supplies such as salmon are more abundant.

Other provinces and the United States may use a combination of methods for population estimates. Therefore, it is difficult to say precisely what methods were used to produce total population estimates for Canada and North America, as they were likely developed from a variety of studies. The grizzly bear currently has legal protection in Mexico, European countries, some areas of Canada and in the United States. However, it is expected that repopulating its former range will be a slow process, due to a variety of reasons including the reintroduction of competing predators to these areas, the effects of reintroducing such a large animal to areas prized for agriculture and livestock, and due to the bear's slow reproductive habits. There are currently about 55,000 wild grizzly bears located throughout North America.

Longevity

The grizzly bear is by nature a long-living animal. Females live longer than males due to their less dangerous life, avoiding the seasonal breeding fights males engage in. The average lifespan for a male is estimated at 22 years, with that of a female being slightly longer at 26. The oldest known wild grizzly was 34 years old in Alaska. Captive grizzlies have lived as long as 44 years, but most grizzlies inevitably die in their first few years of life from predation or hunting.

Hibernation

Grizzly bears hibernate for 5–7 months each year. During this time, female grizzly bears give birth to their offspring, who then consume milk from their mother and gain strength for the remainder of the hibernation period. To prepare for hibernation, grizzlies must prepare a den, and consume an immense amount of food as they do not eat during hibernation. Grizzly bears do not defecate or urinate throughout the entire hibernation period. The male grizzly bear's hibernation ends in early to mid March, while females emerge in April or early May.

In preparation for winter, bears can gain approximately 400 lb (180 kg), during a period of hyperphagia, before going into false hibernation. The bear often waits for a substantial snowstorm before it enters its den: such behavior lessens the chances predators will find the den. The dens are typically at elevations above 1,800 m (5,900 ft) on north-facing slopes. There is some debate amongst professionals as to whether grizzly bears technically hibernate: much of this debate revolves around body temperature and the ability of the bears to move around during hibernation on occasion. Grizzly bears can "partially" recycle their body wastes during this period. Although inland or Rocky Mountain grizzlies spend nearly half of their life in dens, coastal grizzlies with better access to food sources spend less time in dens. In some areas where food is very plentiful year round, grizzly bears skip hibernation altogether.

Reproduction

Sow with two cubs

Grizzly bears have one of the lowest reproductive rates of all terrestrial mammals in North America. This is due to numerous ecological factors. Grizzly bears do not reach sexual maturity until they are at least five years old. Once mated with a male in the summer, the female delays embryo implantation until hibernation, during which miscarriage can occur if the female does not receive the proper nutrients and caloric intake. On average, females produce two cubs in a litter and the mother cares for the cubs for up to two years, during which the mother will not mate. Once the young leave or are killed, females may not produce another litter for three or more years, depending on environmental conditions. Male grizzly bears have large territories, up to 4,000 km² (1,500 sq mi), making finding a female scent difficult in such low population densities.

Grizzlies are subject to population fragmentation, which tends to reduce the population by causing inbreeding depression. The gestation period for grizzly bears is approximately 180–250 days.

Litter size is between one and four cubs, averaging twins or triplets. Cubs are always born in the mother's winter den while she is in hibernation. Female grizzlies are fiercely protective of their cubs, being able to fend off predators as large as male bears bigger than they are in defense of the cubs. Cubs feed entirely on their mother's milk until summer comes, after which they still drink milk but begin to eat solid foods. Cubs gain weight rapidly during their time with the mother — their weight will have ballooned from 10 to over 100 pounds (45 kg) in the two years spent with the mother. Mothers may see their cubs in later years but both avoid each other.

Diet

Grizzly bear fishing for salmon at Brooks Falls, Alaska

Mother grizzly with a cub

Although grizzlies are of the order Carnivora and have the digestive system of carnivores, they are normally omnivores: their diets consist of both plants and animals. They have been known to prey on large mammals, when available, such as moose, elk, caribou, white-tailed deer, mule deer, bighorn sheep, bison, and even black bears; though they are more likely to take calves and injured individuals rather than healthy adults. Grizzly bears feed on fish such as salmon, trout, and bass, and those with access to a more protein-enriched diet in coastal areas potentially grow larger than inland individuals. Grizzly bears also readily scavenge food or carrion left behind by other animals. Grizzly bears will also eat birds and their eggs, and gather in large numbers at fishing sites to feed on spawning salmon. They frequently prey on baby deer left in the grass, and occasionally they raid the nests of raptors such as bald eagles.

Canadian or Alaskan grizzlies are larger than those that reside in the American Rocky Mountains. This is due, in part, to the richness of their diets. In Yellowstone National Park in the United States, the grizzly bear's diet consists mostly of whitebark pine nuts, tubers, grasses, various rodents, army cutworm moths, and scavenged carcasses. None of these, however, match the fat content of the salmon available in Alaska and British Columbia. With the high fat content of salmon, it is not uncommon to encounter grizzlies in Alaska weighing 1,200 pounds (544 kg). Grizzlies in Alaska supplement their diet of salmon and clams with sedge grass and berries. In areas where salmon are forced to leap waterfalls, grizzlies gather at the base of the falls to feed on and catch the fish. Salmon are at a disadvantage when they leap waterfalls because they cluster together at their bases and are therefore easier targets for the grizzlies. Grizzly bears are well-documented catching leaping salmon in their mouths at Brooks Falls in Katmai National Park and Preserve in Alaska. They are also very experienced in chasing the fish around and pinning them with their claws. At such sites such as Brooks Falls and McNeil Falls in Alaska, big male grizzlies fight regularly for the best fishing spots. Grizzly bears along the coast also forage for razor clams, and frequently dig into the sand to seek them. During the spring and fall, directly before and after the salmon runs, berries and grass make up the mainstay of the diets of coastal grizzlies.

Inland grizzlies may eat fish too, most notably in Yellowstone grizzlies eating cutthroat trout. The relationship with cutthroat trout and grizzlies is unique because it is the only example where Rocky Mountain grizzlies feed on spawning salmonid fish. However, grizzly bears themselves and invasive lake trout threaten the survival of the trout population and there is a slight chance that the trout will be eliminated.

Meat, as already described, is an important part of a grizzly's diet. Grizzly bears occasionally prey on small mammals, such as marmots, ground squirrels, lemmings, and voles. The most famous example of such predation is in Denali National Park and Preserve, where grizzlies chase, pounce on, and dig up Arctic ground squirrels to eat. In some areas, grizzly bears prey on hoary marmots, overturning rocks to reach them, and in some cases preying on them when they are in hibernation. Larger prey includes bison and moose, which are sometimes taken by bears in Yellowstone National Park. Because bison and moose are dangerous prey, grizzlies usually use cover to stalk them and/or pick off weak individuals or calves. Grizzlies in Alaska also regularly prey on moose calves, which in Denali National Park may be their main source of meat. In fact, grizzly bears are such important predators of moose and elk calves in Alaska and in Yellowstone, that they may kill as many as 51 percent of elk or moose calves born that year. Grizzly bears have also been blamed in the decline of elk in Yellowstone National Park when the actual predators were thought to be gray wolves. In northern Alaska, grizzlies are a significant predator of caribou, mostly taking sick or old individuals or calves. Several studies show that grizzly bears may follow the caribou herds year-round in order to maintain their food supply. In northern Alaska, grizzly bears often encounter muskox. Despite the fact that muskox do not usually occur in grizzly habitat and that they are bigger and more powerful than caribou, predation on muskox by grizzlies has been recorded.

Grizzly bears along the Alaskan coast also scavenge on dead or washed up whales. Usually such incidents involve only one or two grizzlies at a carcass, but up to ten large males have been seen at a time eating a dead humpback whale. Dead seals and sea lions are also consumed.

Although the diets of grizzly bears vary extensively based on seasonal and regional changes, plants make up a large portion of them, with some estimates as high as 80–90%. Various berries constitute an important food source when they are available. These can include blueberries, blackberries (Rubus fruticosus), salmon berries (Rubus spectabilis), cranberries (Vaccinium oxycoccus), buffalo berries (Shepherdia argentea), and huckleberries (Vaccinium parvifolium), depending on the environment. Insects such as ladybugs, ants, and bees are eaten if they are available in large quantities. In Yellowstone National Park, grizzly bears may obtain half of their yearly caloric needs by feeding on miller moths that congregate on mountain slopes. When food is abundant, grizzly bears will feed in groups. For example, many grizzly bears will visit meadows right after an avalanche or glacier slide. This is due to an influx of legumes, such as Hedysarum, which the grizzlies consume in massive amounts. When food sources become scarcer, however, they separate once again.

Interspecific competition

Grizzly bear cub in Western Canada

With the reintroduction of gray wolves to Yellowstone, many visitors have witnessed a once common struggle between a keystone species, the grizzly bear, and its historic rival, the gray wolf. The interactions of U. arctos horribilis with the wolves of Yellowstone have been under considerable study. Typically, the conflict will be in the defense of young or over a carcass, which is commonly an elk killed by wolves. The grizzly bear uses its keen sense of smell to locate the kill. As the wolves and grizzly compete for the kill, one wolf may try to distract the bear while the others feed. The bear then may retaliate by chasing the wolves. If the wolves become aggressive with the bear, it is normally in the form of quick nips at its hind legs. Thus, the bear will sit down and use its ability to protect itself in a full circle. Rarely do interactions such as these end in death or serious injury to either animal. One carcass simply is not usually worth the risk to the wolves (if the bear has the upper hand due to strength and size) or to the bear (if the wolves are too numerous or persistent). While wolves usually dominate grizzly bears during interactions at wolf dens, both grizzly and black bears have been reported killing wolves and their cubs at wolf dens even when the latter was in defense mode.

Black bears generally stay out of grizzly territory, but grizzlies may occasionally enter black bear terrain to obtain food sources both bears enjoy, such as pine nuts, acorns, mushrooms, and berries. When a black bear sees a grizzly coming, it either turns tail and runs or climbs a tree. Black bears are not strong competition for prey because they have a more herbivorous diet. Confrontations are rare because of the differences in size, habitats, and diets of the bear species. When this happens, it is usually with the grizzly being the aggressor. The black bear will only fight when it is a smaller grizzly such as a yearling or when the black bear has no other choice but to defend itself. There is at least one confirmed observation of a grizzly bear digging out, killing and eating a black bear when the latter was in hibernation.

The segregation of black bear and grizzly bear populations is possibly due to competitive exclusion. In certain areas, grizzly bears outcompete black bears for the same resources. For example, many Pacific coastal islands off British Columbia and Alaska support either the black bear or the grizzly, but rarely both. In regions where both species coexist, they are divided by landscape gradients such as age of forest, elevation and openness of land. Grizzly bears tend to favor old forests with high productivity, higher elevations and more open habitats compared with black bears.

The relationship between grizzly bears and other predators is mostly one-sided; grizzly bears will approach feeding predators to steal their kill. In general, the other species will leave the carcasses for the bear to avoid competition or predation. Any parts of the carcass left uneaten are scavenged by smaller animals. Cougars generally give the bears a wide berth. Grizzlies have less competition with cougars than with other predators, such as coyotes, wolves, and other bears. When a grizzly descends on a cougar feeding on its kill, the cougar usually gives way to the bear. When a cougar does stand its ground, it will use its superior agility and its claws to harass the bear, yet stay out of its reach until one of them gives up. Grizzly bears occasionally kill cougars in disputes over kills. There have been several accounts, primarily from the late 19th and early 20th centuries, of cougars and grizzly bears killing each other in fights to the death.

Coyotes, foxes, and wolverines are generally regarded as pests to the grizzlies rather than competition, though they may compete for smaller prey, such as ground squirrels and rabbits. All three will try to scavenge whatever they can from the bears. Wolverines are aggressive enough to occasionally persist until the bear finishes eating, leaving more than normal scraps for the smaller animal. Packs of coyotes have also displaced grizzly bears in disputes over kills.

Ecological role

The grizzly bear has several relationships with its ecosystem. One such relationship is a mutualistic relationship with fleshy-fruit bearing plants. After the grizzly consumes the fruit, the seeds are dispersed and excreted in a germinable condition. Some studies have shown germination success is indeed increased as a result of seeds being deposited along with nutrients in feces. This makes grizzly bears important seed distributors in their habitats.

While foraging for tree roots, plant bulbs, or ground squirrels, bears stir up the soil. This process not only helps grizzlies access their food, but also increases species richness in alpine ecosystems. An area that contains both bear digs and undisturbed land has greater plant diversity than an area that contains just undisturbed land. Along with increasing species richness, soil disturbance causes nitrogen to be dug up from lower soil layers, and makes nitrogen more readily available in the environment. An area that has been dug by the grizzly bear has significantly more nitrogen than an undisturbed area.

Nitrogen cycling is not only facilitated by grizzlies digging for food, it is also accomplished via their habit of carrying salmon carcasses into surrounding forests. It has been found that spruce tree (Picea glauca) foliage within 500 m (1,600 ft) of the stream where the salmon have been obtained contains nitrogen originating from salmon on which the bears preyed. These nitrogen influxes to the forest are directly related to the presence of grizzly bears and salmon.

Grizzlies directly regulate prey populations and also help prevent overgrazing in forests by controlling the populations of other species in the food chain. An experiment in Grand Teton National Park in Wyoming in the United States showed removal of wolves and grizzly bears caused populations of their herbivorous prey to increase. This, in turn, changed the structure and density of plants in the area, which decreased the population sizes of migratory birds. This provides evidence grizzly bears represent a keystone predator, having a major influence on the entire ecosystem they inhabit.

When grizzly bears fish for salmon along the coasts of Alaska and British Columbia, they often only eat the skin, brain and roe of the fish. In doing so, they provide a food source for gulls, ravens, and foxes, all or which eat salmon as well; this benefits both the bear and the smaller predators.

Conflicts with humans

Grizzlies are considered by some experts to be more aggressive than black bears when defending themselves and their offspring. Aggressive behavior in grizzly bears is favored by numerous selection variables. Unlike the smaller black bears, adult grizzlies are too large to escape danger by climbing trees, so they respond to danger by standing their ground and warding off their attackers. Increased aggressiveness also assists female grizzlies in better ensuring the survival of their young to reproductive age. Mothers defending their cubs are the most prone to attacking, being responsible for 70% of fatal injuries to humans. Historically, bears have competed with other large predators for food, which also favors increased aggression.

Campers are warned to hang food, garbage, and toiletries out of reach of bears, or to use a secure bear cache.

Grizzly bears normally avoid contact with people. In spite of their obvious physical advantages and many opportunities, they almost never view humans as prey; bears rarely actively hunt humans. Most grizzly bear attacks result from a bear that has been surprised at very close range, especially if it has a supply of food to protect, or female grizzlies protecting their offspring. In such situations, property may be damaged and the bear may physically harm the person.

Exacerbating this is the fact that intensive human use of grizzly habitat coincides with the seasonal movement of grizzly bears. An example of this spatiotemporal intersection occurs during the fall season: grizzly bears congregate near streams to feed on salmon when anglers are also intensively using the river.

Increased human–bear interaction has created "problem bears", which are bears that have become adapted to human activities or habitat. Aversive conditioning, a method involving using deterrents such as rubber bullets, foul-tasting chemicals or acoustic devices to teach bears to associate humans with negative experiences, is ineffectual when bears have already learned to positively associate humans with food. Such bears are translocated or killed because they pose a threat to humans. The B.C. government kills approximately 50 problem bears each year and overall spends more than one million dollars annually to address bear complaints, relocate bears and kill them.

For back-country campers, hanging food between trees at a height unreachable to bears is a common procedure, although some grizzlies can climb and reach hanging food in other ways. An alternative to hanging food is to use a bear canister.

Traveling in groups of six or more can significantly reduce the chance of bear-related injuries while hiking in bear country.

Grizzly bears are especially dangerous because of the strength of their bite, which has been measured at over 8 megapascals (1160 psi). It has been estimated that a bite from a grizzly could crush a bowling ball.

Protection

A grizzly in Denali National Park

The grizzly bear is listed as threatened in the contiguous United States and endangered in parts of Canada. In May 2002, the Canadian Species at Risk Act listed the Prairie population (Alberta, Saskatchewan and Manitoba range) of grizzly bears as being wiped out in Canada. As of 2002, grizzly bears were listed as Special Concern under the COSEWIC registry and considered threatened under the U.S. Fish and Wildlife Service.

Within the United States, the U.S. Fish and Wildlife Service concentrates its effort to restore grizzly bears in six recovery areas. These are Northern Continental Divide (Montana), Yellowstone (Montana, Wyoming, and Idaho), Cabinet-Yaak (Montana and Idaho), Selway-Bitterroot (Montana and Idaho), Selkirk (Idaho and Washington), and North Cascades (Washington). The grizzly population in these areas is estimated at 750 in the Northern Continental Divide, 550 in Yellowstone, 40 in the Yaak portion of the Cabinet-Yaak, and 15 in the Cabinet portion (in northwestern Montana), 105 in Selkirk region of Idaho, 10–20 in the North Cascades, and none currently in Selway-Bitterroots, although there have been sightings. These are estimates because bears move in and out of these areas, and it is therefore impossible to conduct a precise count. In the recovery areas that adjoin Canada, bears also move back and forth across the international boundary.

The U.S. Fish and Wildlife Service claims the Cabinet-Yaak and Selkirk areas are linked through British Columbia, a claim that is disputed.

All national parks, such as Banff National Park, Yellowstone and Grand Teton, and Theodore Roosevelt National Park have laws and regulations in place to protect the bears. Even so, grizzlies are not always safe in parks. In Glacier National Park in Montana and Banff National Park in Alberta, grizzlies are regularly killed by trains as the bears scavenge for grain that has leaked from poorly maintained grain cars. Road kills on park roads are another problem. The primary limiting factors for grizzly bears in Alberta and elsewhere are human-caused mortality, unmitigated road access, and habitat loss, alienation, and fragmentation. In the Central Rocky Mountains Ecosystem, most bears have died within a few hundred meters of roads and trails.

On 9 January 2006, the US Fish and Wildlife Service proposed to remove Yellowstone grizzlies from the list of threatened and protected species. In March 2007, the U.S. Fish and Wildlife Service "de-listed" the population, effectively removing Endangered Species Act protections for grizzlies in the Yellowstone National Park area. Several environmental organizations, including the NRDC, brought a lawsuit against the federal government to relist the grizzly bear. On September 22, 2009, U.S. District Judge Donald W. Molloy reinstated protection due to the decline of whitebark pine tree, whose nuts are a main source of food for the bears. In 1996 the International Union for Conservation of Nature moved the grizzly bear to "Lower Risk Least Concern" status on the IUCN Red List.

Farther north, in Alberta, Canada, intense DNA hair-snagging studies on 2000 showed the grizzly population to be increasing faster than what it was formerly believed to be, and Alberta Sustainable Resource Development calculated a population of 841 bears. In 2002, the Endangered Species Conservation Committee recommended that the Alberta grizzly bear population be designated as threatened due to recent estimates of grizzly bear mortality rates that indicated the population was in decline. A recovery plan released by the Provincial government in March 2008 indicated the grizzly population is lower than previously believed. In 2010, the Provincial government formally listed its population of about 700 grizzlies as "Threatened".

Environment Canada consider the grizzly bear to a "special concern" species, as it is particularly sensitive to human activities and natural threats. In Alberta and British Columbia, the species is considered to be at risk. In 2008, it was estimated there were 16,014 grizzly bears in the British Columbia population, which was lower than previously estimated due to refinements in the population model.

The Mexican grizzly bear (Ursus arctos nelsoni) is extinct.

Conservation efforts

Drum or barrel trap used to safely relocate bears adjacent to a building in Grand Teton National Park in Wyoming, United States

Conservation efforts have become an increasingly vital investment over recent decades, as population numbers have dramatically declined. Establishment of parks and protected areas are one of the main focuses currently being tackled to help reestablish the low grizzly bear population in British Columbia. One example of these efforts is the Khutzeymateen Grizzly Bear Sanctuary located along the north coast of British Columbia; at 44,300 hectares (109,000 acres) in size, it is composed of key habitat for this threatened species. Regulations such as limited public access, as well as a strict no hunting policy, have enabled this location to be a safe haven for local grizzlies in the area. When choosing the location of a park focused on grizzly bear conservation, factors such as habitat quality and connectivity to other habitat patches are considered.

The Refuge for Endangered Wildlife located on Grouse Mountain in Vancouver is an example of a different type of conservation effort for the diminishing grizzly bear population. The refuge is a five-acre terrain which has functioned as a home for two orphaned grizzly bears since 2001. The purpose of this refuge is to provide awareness and education to the public about grizzly bears, as well as providing an area for research and observation of this secluded species.

Another factor currently being taken into consideration when designing conservation plans for future generations are anthropogenic barriers in the form of urban development and roads. These elements are acting as obstacles, causing fragmentation of the remaining grizzly bear population habitat and prevention of gene flow between subpopulations (for example, Banff National Park). This, in turn, is creating a decline in genetic diversity, and therefore the overall fitness of the general population is lowered. In light of these issues, conservation plans often include migration corridors by way of long strips of "park forest" to connect less developed areas, or by way of tunnels and overpasses over busy roads. Using GPS collar tracking, scientists can study whether or not these efforts are actually making a positive contribution towards resolving the problem. To date, most corridors are found to be infrequently used, and thus genetic isolation is currently occurring, which can result in inbreeding and therefore an increased frequency of deleterious genes through genetic drift. Current data suggest female grizzly bears are disproportionately less likely than males to use these corridors, which can prevent mate access and decrease the number of offspring.

Bear-watching

In the past 20 years in Alaska, ecotourism has boomed. While many people come to Alaska to bear-hunt, the majority come to watch the bears and observe their habits. Some of the best bear viewing in the world occurs on coastal areas of the Alaska Peninsula, including in Lake Clark National Park and Preserve, Katmai National Park and Preserve, and the McNeil River State Game Sanctuary and Refuge. Here bears gather in large numbers to feast on concentrated food sources, including sedges in the salt marshes, clams in the nearby tidal flats, salmon in the estuary streams, and berries on the neighboring hillsides.

Katmai National Park and Preserve is one of the best spots to view brown bears. The bear population in Katmai is estimated at a healthy 2100. The park is located on the Alaskan Peninsula about 300 miles south of the city of Anchorage. At Brooks Camp, a famous site exists where grizzlies can be seen catching salmon from atop a platform—you can even view this online from a cam. In coastal areas of the park, such as Hallo Bay, Geographic Harbor, Swikshak Lagoon, American Creek, Big River, Kamishak River, Savonoski River, Moraine Creek, Funnel Creek, Battle Creek, Nantuk Creek, Kukak Bay, and Kaflia Bay you can often watch bears fishing alongside wolves, eagles, and river otters. Coastal areas host the highest population densities year round because there is a larger viariety of food sources available, but Brooks Camp hosts the highest population (100 bears).

The McNeil River State Game Sanctuary and Refuge, on the McNeil River, is home to the greatest concentration of brown bears in the world. An estimated 144 individual bears have been identified at the falls in a single summer with as many as 74 at one time; 60 or more bears at the falls is a frequent sight, and it is not uncommon to see 100 bears at the falls throughout a single day. The McNeil River State Game Refuge, containing Chenik Lake and a smaller number of grizzly bears, has been closed to grizzly hunting since 1995. All of the Katmai-McNeil area is closed to hunting except for Katmai National Preserve, where regulated legal hunting takes place. In all, the Katmai-McNeil area has an estimated 2500 grizzly bears.

Admiralty Island, in southeast Alaska, was known to early natives as Xootsnoowú, meaning "fortress of bears," and is home to the densest grizzly population in North America. An estimated 1600 grizzlies live on the island, which itself is only 90 miles long. The best place to view grizzly bears in the island is probably Pack Creek, in the Stan Price State Wildlife Sanctuary. 20 to 30 grizzlies can be observed at the creek at one time and like Brooks Camp, visitors can watch bears from an above platform. Kodiak Island, hence its name, is another good place to view bears. An estimated 3500 Kodiak grizzly bears inhabit the island, 2300 of these in the Kodiak National Wildlife Refuge. The O'Malley River is considered the best place on Kodiak Island to view grizzly bears.

Hunting

Trophy hunting causes an imbalance between the sexes, as hunters target primarily older males for their size. Older males' deaths allow other males to migrate in and claim the territory. Older male bears will have had cubs with female bears in the region. This may cause the newly migrated male bears to become infanticidal towards the late males' cubs.

Grizzly bear hunting for the purpose of wildlife management is permitted in British Columbia, Canada. Approximately 1602 special hunting license "tags" were drawn for via lottery & sold throughout all of B.C. in 2012, by the Ministry of Forests, Lands and Natural Resource Operations (a provincial government department). The Canadian government website notes that killing female grizzly bears is detrimental to the re-population of the species, and encourages culling of males.

See also

• Brown bear
• Grizzly–polar bear hybrid
• Grizzly Peak (Berkeley Hills)
• List of fatal bear attacks in North America
• Hunting status on grizzly bears in British Columbia, Canada
• "Grizzly Bear Standing", Kalispel chief
• Timothy Treadwell

References

Further reading

• "Ursus arctos horribilis". Integrated Taxonomic Information System. Retrieved 18 March 2006. 
• Banfield, A. W. F. (1987). The Mammals of Canada. Toronto: University of Toronto Press. 
• CBC News article on possible "grolar bear" (Polar Bear/Grizzly Bear hybrid)
• Committee On The Status of Endangered Wildlife in Canada (COSEWIC) Assessment and Update Status Report on the Grizzly Bear (Ursus arctos) in Canada, 2002 2.1 MB PDF file.
• Cronin, M. A. et al. (1991). "Interspecific and specific mitochondrial DNA variation in North American bears (Ursus)". Canadian Journal of Zoology 69 (12): 2985–2992. doi:10.1139/z91-421. 
• Herrero, Stephen (1985). Bear Attacks. Piscataway, NJ: New Centuries Publishers. ISBN 0-8329-0377-9. 
• Waits, L. P. et al. (1998). "Mitochondrial DNA phylogeography of the North American brown bear and implications for conservation". Conservation Biology 12 (2): 408–417. doi:10.1046/j.1523-1739.1998.96351.x. 
• Snyder, Susan (2003). The California Grizzly Bear in Mind. Berkeley: University of California Press. 
• Mattson, J.; Merrill, Troy (2001). "Extirpations of Grizzly Bears in the Contiguous United States, 1850–2000". Conservation Biology 16 (4): 1123–1136. doi:10.1046/j.1523-1739.2002.00414.x. 
• Wielgus, R. B. (2002). "Minimum viable population and reserve sizes for naturally regulated grizzly bears in British Columbia". Biological Conservation 106 (3): 381–388. doi:10.1016/S0006-3207(01)00265-8. 
• Groom, M. J.; Meffe, G. K.; Carroll, C. R. (2006). Principles of Conservation Biology (3rd ed.). Sunderland, MA: Sinauer Associates. 
• Murie, Adolph (1985). The grizzlies of Mount McKinley. Seattle: University of Washington Press. ISBN 0-295-96204-6. 
• McCory, W.P., Herrero, S.M., Jones, G.W., & Mallam, E.D. (1990). A Selection of Papers from the Eighth International Conference on Bear Research and Management, Victoria, British Columbia, Canada. Bears: Their Biology and Management 8. pp. 11–16. 
• Proctor, M.F., McLellan, B.N., Strobeck, C., & Barclay, R.M.R. (2005). "Genetic analysis reveals demographic fragmentation of grizzly bears yielding vulnerably small populations". Proc Biol Sci. 272 (1579): 2409–2416. doi:10.1098/rspb.2005.3246. PMC 1559960. PMID 16243699. 

External links

• Smithsonian National Museum of Natural History species account-Grizzly Bear
• Are Grizzly Bears Dangerous?, grizzlybay.org
• The Yellowstone Grizzly

English Journal

• PLANT CONSUMPTION BY GRIZZLY BEARS REDUCES BIOMAGNIFICATION OF SALMON-DERIVED POLYCHLORINATED BIPHENYLS, POLYBROMINATED DIPHENYL ETHERS, AND ORGANOCHLORINE PESTICIDES.

• Christensen JR, Yunker MB, Macduffee M, Ross PS.SourceInstitute of Ocean Sciences, Fisheries & Oceans Canada, Sidney, British Columbia, Canada; School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia, Canada; Raincoast Conservation Foundation, Sidney, British Columbia, Canada.
• Environmental toxicology and chemistry / SETAC.Environ Toxicol Chem.2013 Feb 11. doi: 10.1002/etc.2162. [Epub ahead of print]
• The present study characterizes the uptake and loss of persistent organic pollutants (POPs) in grizzly bears (Ursus arctos horribilis) by sampling and analyzing their terrestrial and marine foods and fecal material from a remote coastal watershed in British Columbia, Canada. The authors estimate tha
• PMID 23401324

• Temperature-driven range expansion of an irruptive insect heightened by weakly coevolved plant defenses.

• Raffa KF, Powell EN, Townsend PA.SourceDepartment of Entomology, University of Wisconsin, Madison, WI 53706, USA. kfraffa@wisc.edu
• Proceedings of the National Academy of Sciences of the United States of America.Proc Natl Acad Sci U S A.2013 Feb 5;110(6):2193-8. doi: 10.1073/pnas.1216666110. Epub 2012 Dec 31.
• Warming climate has increased access of native bark beetles to high-elevation pines that historically received only intermittent exposure to these tree-killing herbivores. Here we show that a dominant, relatively naïve, high-elevation species, whitebark pine, has inferior defenses against mountain
• PMID 23277541

• Does learning or instinct shape habitat selection?

• Nielsen SE, Shafer AB, Boyce MS, Stenhouse GB.SourceDepartment of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada. scottn@ualberta.ca
• PloS one.PLoS One.2013;8(1):e53721. doi: 10.1371/journal.pone.0053721. Epub 2013 Jan 16.
• Habitat selection is an important behavioural process widely studied for its population-level effects. Models of habitat selection are, however, often fit without a mechanistic consideration. Here, we investigated whether patterns in habitat selection result from instinct or learning for a populatio
• PMID 23341983

• Examining market trends in the United States smokeless tobacco use: 2005-2011.

• Delnevo CD, Wackowski OA, Giovenco DP, Manderski MT, Hrywna M, Ling PM.SourceCenter for Tobacco Surveillance & Evaluation Research, University of Medicine & Dentistry of NJ-School of Public Health, New Brunswick, New Jersey, USA.
• Tobacco control.Tob Control.2012 Oct 31. [Epub ahead of print]
• BACKGROUND: While cigarette consumption in the USA continues to decline, promotion for and consumption of smokeless tobacco (SLT) is growing. However, little research has explored what product features are driving SLT growth, despite awareness that product-level factors may be important in SLT use.
• PMID 23117999

Japanese Journal

• アブレシブウオータージェット切断を利用した高クロム鋳鉄肉盛溶接製篩分器の開発

• 本田 嗣男,黒木 博憲,山口 富子,西尾 一政
• 鋳造工学 = Journal of Japan Foundry Engineering Society 83(9), 519-524, 2011-09-25
• NAID 10029579889

• AIRBUS MILITARY A400M GRIZZLY

• 航空技術 (667), 24-29, 2010-10
• NAID 40017326692

• Grizzly見参 ROYAL INTERNATIONAL AIR TATTOO 2010 RIATを乱舞したエアバスA400Mと各国軍用機

• Tokunaga Katsuhiko
• 航空ファン 59(10), 16-25, 2010-10
• NAID 40017247475

• Conservation of biodiversity in Canada and Japan : Different policies and different effectiveness

• Fitz-Earle Malcolm,Kobayashi Satoshi
• Biosphere conservation : for nature, wildlife, and humans 9(1), 17-39, 2008-09
• … To illustrate these insights we compare, in a number of case histories, conservation situations of American Black Bear and Asiatic Black Bear, and North American Grizzly and Japanese Brown Bears, Northern Spotted Owl and Blakiston's Fish Owl, and Whooping Cranes and Red-crowned Cranes. …
• NAID 110006987279

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