The brown bear (Ursus arctos) is a large bear distributed across much of northern Eurasia and North America. It weighs 100 to 680 kilograms (220–1,500 lb) and its largest subspecies, the Kodiak Bear, rivals the polar bear as the largest member of the bear family, and as the largest land based predator. While the brown bear's range has shrunk, and it has faced local extinctions, it remains listed as a least concern species by the IUCN, with a total population of approximately 200,000. Its principal range countries are Russia, the United States (especially Alaska), Canada, the Carpathian region (especially Romania), and Finland where it is the national animal. The species primarily feeds on vegetable matter, including roots and fungi. Fish are a primary source of meat. It also eats small land mammals and occasionally larger mammals, such as deer. Adult brown bears 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, meaning brown.
Brown bears have furry coats in shades of blonde, brown, black, or a combination of those colors. The longer outer guard hairs 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 (5.9 in) in length which are mainly used for digging. The 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 meters (5.6 to 9.2 ft) and a shoulder height of 90 to 150 centimeters (35–60 in). The smallest subspecies is the Eurasian Brown Bear whose mature females weigh 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 (330 lb). The largest subspecies are the Kodiak Bear and the Kamchatka Brown Bear. It is not unusual for large male Kodiak Bears to stand over 3 m (9.8 ft) while on their hind legs, and to weigh up to 680 kg (1,500 lb). The largest wild Kodiak Bear on record weighed over 1,100 kilograms (2,400 lb). 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 lb), one example being "Goliath" from New Jersey's Space Farms Zoo and Museum. Another example is Kodiak brown bear "Barbucha" at the zoo in Duisburg, who weighs 1000 kilograms (2200 lb). Size seems related to food availability, and subspecies distinctions is more related to nutrition than geographical location. Despite their size, some brown bears have been clocked at speeds in excess of 64 km/h (40 mph). One of the subspecies of the brown bear, the Kodiak Bear, which is native to Kodiak Island, matches the polar bear as the largest member of the bear family, and as the largest land predator. The hides and skulls of the two species are comparable in size, thus making morphological comparisons difficult as it is often difficult to weigh wild specimens.
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 lower 48 they are repopulating slowly but steadily along the Rockies and plains. Although many people 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 fragmented populations, from Spain in the west, to Russia in the east, and from Scandinavia in the north to Romania, Bulgaria, Slovakia (with about 800–900 animals), 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 Carpathian brown bear population is the largest in Europe outside Russia, estimated at 4,500 to 5,000 bears. Scandinavia is home to a large bear population, with an estimated 2,500 (range 2,350–2,900) in Sweden, 840 in Finland, and 70 in Norway. Another large and relatively stable population of brown bears in Europe, consisting of 2,500–3,000 individuals, is the Dinaric-Pindos (Balkans) population, with contiguous distribution in North-East Italy, Slovenia, Croatia, Bosnia and Herzegovina, Serbia, Montenegro, Macedonia, Albania, and Greece. 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 14 to 18 with a shortage of females, that bears, mostly female, from Slovenia were released in spring 2006 to reduce the imbalance and preserve the species' presence in the area, despite protests from French farmers. A little population of brown bears (Ursus arctos marsicanus) still lives in central Italy (Apennine mountains, Abruzzo and Latium) with no more than 70 speciemens, protected by severe laws but endangered for the strong human presence in the area. In Arctic areas, the potential habitat of the brown bear is increasing. The warming of that region has allowed the species to move 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. This is 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.
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 highly 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 areas based on opportunity. 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. In some areas of Russia and Alaska, brown bears feed mostly on spawning salmon, whose nutrition and abundance explains the enormous size of the bears in these areas. Brown bears also occasionally prey on large mammals, such as deer, elk, moose, caribou, and bison. When brown bears attack these animals, they tend to choose the young ones as they are 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, such as bison. They also feed on carrion and use their size to intimidate other predators such as wolves, cougars, tigers, and black bears from their kills.
The mating season is from late May to early July. Being serially monogamous, brown bears remain with the same mate from several days to a couple of weeks. Females mature sexually between the age of 5 and 7 years, while males usually mate a few years later when they are large and strong enough to successfully compete with other males for mating rights. Through the process of delayed implantation, a female's fertilized egg divides and floats free in the uterus for six months. During winter dormancy, the fetus attaches to the uterine wall. The cubs are born eight weeks later, while the mother sleeps. If the mother does not gain enough weight to survive through the winter, the embryo does not implant and is reabsorbed into the body. The average litter has one to four cubs, usually two. There have been cases of bears with five cubs, though sometimes females adopt strange cubs. Older females tend to give birth to larger litters. The size of a litter also depends on factors such as geographic location and food supply. At birth, the cubs are blind, toothless, hairless, and weigh less than 1 pound. They feed on their mother's milk until spring or even early summer depending on climate conditions. At this time, the cubs weigh 15 to 20 pounds and have developed enough to follow her and begin to forage for solid food.
Cubs remain with their mother from two to four years, during which time they learn survival techniques, such as which foods have the highest nutritional values and where to attain them; how to hunt, fish, and defend themselves; and where to den. The cubs learn by following and imitating their mother's actions during the period they are with her. Brown bears practice infanticide. An adult male bear may kill the cubs of another bear either to make the female sexually receptive or simply for consumption. Cubs flee up a tree when they see a strange male bear, and the mother defends them even though the male may be twice her size.