The species primarily feeds on vegetable matter, including roots and fungi. Fish are a primary source of meat, and it will also kill small mammals on land. Larger mammals, such as deer, are taken only occasionally. Adult brown bears face no serious competition from other predators and can match wolf packs and large felines, often driving them off their kills.
It is sometimes referred to as the bruin, from Middle English, based on the name of the bear in History of Reynard the Fox, translated by William Caxton, from Middle Dutch bruun or bruyn.
Brown bears have furry coats in shades of blonde, brown, black, or a combination of those colors. The longer outer guard hairs of the brown bear are often tipped with white or silver, giving a "grizzled" appearance. Their tail is 4-5 inches (10-13 cm) long. Like all bears, brown bears are plantigrades and can stand up on their hind legs for extended periods of time. Brown bears have a large hump of muscle over their shoulders which distinguishes them from other species. Brown bears are very powerful, and can break the backs and necks of large prey. The forearms end in massive paws with claws up to 15 cm (6 inches) in length which are mainly used for digging. Brown bear claws are not retractable, and have relatively blunt points. Their heads are large and round with a Concave facial profile, a characteristic used to distinguish them from other bears. Males are 38-50% larger than females. The normal range of physical dimensions for a brown bear is a head-and-body length of 1.7 to 2.8 m (5.6 to 9.2 feet) and a shoulder height 90 to 150 cm (35 to 60 inches). The smallest subspecies is the Eurasian Brown Bear with mature females weighing as little as 90 kg (200 lb). Barely larger, Grizzly Bears from the Yukon region (which are a third smaller than most grizzlies) can weigh as little as 100 kg (220 lb) in the spring and the Syrian Brown Bear, with mature females weighing as little as 150 kg (331 lb). The largest subspecies of the brown bear are the Kodiak bear, Siberian Brown Bear, and the bears from coastal Russia and Alaska. It is not unusual for large male Kodiak Bears to stand over 3 m (10 feet) while on their hind legs and to weigh about 680 kg (1,500 lb). The largest wild Kodiak bear on record weighed over 1,100 kilograms (2,500 pounds).. Bears raised in zoos are often heavier than wild bears because of regular feeding and limited movement. In zoos, bears may weigh up to 900 kilograms (2,000 pounds), one example being "Goliath" from New Jersey's Space Farms Zoo and Museum. Size seems related to food availability, with subspecies distinctions being more related to nutrition rather than geographical location. In spite of their size, some brown bears have been clocked at speeds in excess of 56 km/h (35 mph).
There are about 200,000 brown bears in the world. The largest populations are in Russia, with 120,000, the United States with 32,500, and Canada with 21,750. 95% of the brown bear population in the United States is in Alaska, though in the West they are repopulating slowly but steadily along the Rockies and plains. Although many hold on to the belief that some brown bears may be present in Mexico and the Atlas Mountains of Morocco, both are almost certainly extinct. The last Mexican brown bear was shot in 1960. In Europe, there are 14,000 brown bears in ten separate fragmented populations, from Spain in the west, to Russia in the east, and from Scandinavia in the north to Romania, Bulgaria and Greece (with about 200 animals) in the south. They are extinct in the British Isles, extremely threatened in France and Spain, and in trouble over most of Central Europe. The brown bear is Finland's national animal. The Carpathian brown bear population is the largest in Europe outside Russia, estimated at 4,500 to 5,000 bears.
Brown bears were once native to Asia, the Atlas Mountains in Africa, Europe and North America, but are now extinct in some areas and their populations have greatly decreased in other areas. They prefer semi-open country, usually in mountainous areas.
Brown bears live in Alaska, east through the Yukon and Northwest Territories, south through British Columbia and through the western half of Alberta. Small populations exist in the Greater Yellowstone Ecosystem of northwest Wyoming (with about 600 animals), the Northern Continental Divide Ecosystem of northwest Montana (with about 400-500 animals), the Cabinet-Yaak Ecosystem of northwest Montana and northeast Idaho (with about 30-40 animals), the Selkirk Ecosystem of northeast Washington and northwest Idaho (with about 40-50 animals), and the North Cascades Ecosystem of north-central Washington (with about 5-10 animals). These five ecosystems combine for a total of roughly 1,200 wild grizzlies still persisting in the contiguous United States. Unfortunately, these populations are isolated from each other, inhibiting any genetic flow to occur between ecosystems. This poses one of the greatest threats to the future survival of the grizzly bear in the contiguous United States.
The population of brown bears in the Pyrenees mountain range between France and Spain is so low, estimated at fourteen to eighteen with a shortage of females, that bears, mostly female, from Slovenia were released in the spring of 2006 to alleviate the imbalance and preserve the species' presence in the area, despite protests from French farmers.
In Arctic areas, the potential habitat of the brown bear is increasing. The warming of that region has allowed the species to move farther and farther north into what was once exclusively the domain of the polar bear. In non-Arctic areas, habitat loss is blamed as the leading cause of endangerment, followed by hunting.
North American brown bears seem to prefer open landscapes, whereas in Eurasia they inhabit mostly dense forests. It is thought that the Eurasian bears which colonized America were tundra adapted, something indicated by brown bears in the Chukotka Peninsula on the Asian side of Bering Strait, which are the only Asian brown bears to live year-round in lowland tundra like their American cousins.
The time of the Arctodus extinction is about the same as that of the long-horned Bison and other megafauna. Both of these animals were replaced by Eurasian immigrants, specifically the Brown Bear and American Bison. Since this was also about the same time as the Clovis tool kit hunting culture appeared in North America, with culturally advanced humans entering the Americas from Asia, the implication is that the brown bear was better adapted to human competition than the megafauna, presumably due to a long term coexistence in the Old World with people.
The extinction of ice-age herbivorous megafauna resulted in the extinction of the sabertooth, American lion, and giant short-faced bear, leaving the brown bear as the major large predator in North America, with the gray wolf, the jaguar in the south, the American black bear, and cougar also competing for large prey. The origin of human presence in America is widely accepted to have occurred across the Bering Land Bridge with the largest known immigration being that of the Paleo Indians at about the last ice age, bringing with them the Clovis point and advanced hunting techniques (see: Migration to the New World). When the last ice age ended about 10,000 years ago, brown bears from farther south in North America slowly expanded their range northward and back up into Alaska. Today there are three genetically distinct grizzly bear clades in North America: the Alaskan-Yukon Grizzly, the Alberta-Saskatchewan lineage, and those found in the Colorado-Washington-Idaho-Montana-Wyoming area.
They are omnivores and feed on a variety of plant products, including berries, roots, and sprouts, fungi as well as meat products such as fish, insects, and small mammals. Despite their reputation, most brown bears are not particularly carnivorous as they derive up to 90% of their dietary food energy from vegetable matter. Their jaw structure has evolved to fit their dietary habits. Their diet varies enormously throughout their differing ranges. For example, bears in Yellowstone eat an enormous number of moths during the summer, sometimes as many as 40,000 in a day, and may derive up to half of their annual food energy from these insects. Locally, in areas of Russia and Alaska, brown bears feed mostly on spawning salmon, and the nutrition and abundance of this food accounts for the enormous size of the bears from these areas. Brown bears also occasionally prey on deer, elk, moose, caribou, and bison. When brown bears attack these animals, they tend to choose the young ones since they are much easier to catch. When hunting, the brown bear uses its sharp canine teeth for neck-biting its prey. On rare occasions, bears kill by hitting their prey with their powerful forearms which can break the necks and backs of large prey. They also feed on carrion and will use their size to intimidate other predators such as wolves, cougars, black bears and tigers from their kills.
Adults bears are generally immune from predatory attacks from anything other than another bear. Some bears emerging from hibernation will seek out tigers in order to steal their kills. However, in the Russian Far East brown bears, along with smaller Asiatic black bears constitute 5-8% of the diet of Siberian tigers. In particular, the brown bear's input is estimated as 1-1,5%. However, for the tiger, even bears of the same size are a force to be reckoned with when confronted head on. Adult Brown Bears are known for killing and driving off Adult Male Tigers. There is an opinion that the brown bear/tiger conflict can eliminate the weakest animals from both populations.
Brown bears usually dominate other bear species in areas where they coexist. Due to their smaller size, American black bears are at a competitive disadvantage over brown bears in open, non-forested areas. Although displacement of black bears by brown bears has been documented, actual interspecific killing of black bears by brown bears has only occasionally been reported. The diurnal black bear's habit of living in heavily forested areas as opposed to the largely nocturnal brown bear's preference for open spaces usually ensures that the two species avoid confrontations in areas where they are sympatric. There has been a recent increase in interactions between brown bears and polar bears, theorized to be caused by global warming. Brown bears have been seen moving increasingly northward into territories formerly claimed by polar bears. Brown bears tend to dominate polar bears in disputes over carcasses, and dead polar bear cubs have been found in brown bear dens. Giant Panda cubs have also been reportedly eaten by brown bears.
Bears become attracted to human created food sources such as garbage dumps, litter bins, and dumpsters; and venture into human dwellings or barns in search of food as humans encroach into bear habitat. In the U.S., bears sometimes kill and eat farm animals. When bears come to associate human activity with a "food reward", a bear is likely to continue to become emboldened and the likeliness of human-bear encounters increases, as they may return to the same location despite relocation. The saying, "a fed bear is a dead bear," has come into use to popularize the idea that allowing bears to scavenge human garbage, such as trash cans and campers' backpacks, pet food, or other food sources that draw the bear into contact with humans can result in a bear's death.
Relocation has been used to separate the bear from the human environment, but it does not address the problem bear's newly learned humans-as-food-source behavior. Nor does it address the environmental situations which created the human habituated bear. "Placing a bear in habitat used by other bears may lead to competition and social conflict, and result in the injury or death of the less dominant bear.
Yellowstone National Park, an enormous reserve located in the Western United States, contains prime habitat for the Grizzly Bear (Ursus arctos horribilis), but due to the enormous number of visitors, human-bear encounters are common. The scenic beauty of the area has led to an influx of people moving into the area. In addition, because there are so many bear relocations to the same remote areas of Yellowstone, and because male bears tend to dominate the center of the relocation zone, female bears tend to be pushed to the boundaries of the region and beyond. The result is that a large proportion of repeat offenders, bears that are killed for public safety, are females. This creates a further depressive effect on an already endangered species. The grizzly bear is officially described as threatened in the U.S. Though the problem is most significant with regard to grizzlies, these issues affect the other types of brown bear as well.
In Europe, part of the problem lies with shepherds; over the past two centuries, many sheep and goat herders have gradually abandoned the more traditional practice of using dogs to guard flocks, which have concurrently grown larger. Typically they allow the herds to graze freely over sizeable tracts of land. As bears reclaim parts of their range, they may eat livestock. In some cases, the shepherd will shoot the bear thinking that his livelihood is under threat. Many are now better informed about the ample compensation available and will make a claim when a loss to his livestock due to a bear takes place.
There is little agreement on classification of brown bears. Some systems have proposed as many as 90 sub-species while recent DNA analysis has identified as few as five clades. DNA analysis has recently revealed that the identified subspecies of brown bears, both Eurasian and North American, are genetically quite homogeneous, and that their genetic phylogeography does not correspond to their traditional taxonomy. The subspecies of brown bears have been listed as follows: one of which (called clade I by Waits, et al., part of the subspecies identified as U. a. sitkensis, by Hall and U. a. dalli by Kurtén) appears to be more closely related to the polar bear than to other brown bears.
A grizzly–polar bear hybrid is a rare ursid hybrid resulting from a union of a brown bear and a polar bear. It has occurred both in captivity and in the wild. In 2006, the occurrence of this hybrid in nature was confirmed by testing the DNA of a strange-looking bear that had been shot in the Canadian arctic. Previously, the hybrid had been produced in zoos and was considered a "cryptid" (a hypothesized animal for which there is no scientific proof of existence in the wild).
The Alaska Science Center ranks the following as the most likely reasons for bear attacks:
If a bear is killed near camp the bear’s carcass must be adequately disposed of, including entrails and blood if possible. Failure to move the carcass has often resulted in it attracting other bears and further exacerbating a bad situation.