The brown bear (Ursus arctos) is a large bear with the widest distribution of any bear species.
They are found in the forests and mountains of northern North America, Europe, and Asia.
The brown bear’s principal range includes parts of Russia, Central Asia, China, Canada, the United States (mostly Alaska), Scandinavia and the Carpathian region (especially Romania), Anatolia, and Caucasus.
Brown bears can be found in many habitats, from the fringes of deserts to high mountain forests and ice fields. In Europe, the brown bear is mostly found in mountain woodlands, in Siberia it occurs primarily in forests while in North America they prefer tundra, alpine meadows and coastlines. The species’ main requirements are areas with dense cover in which they can shelter by day.
There are 16 subspecies of brown bears including grizzly bears and Kodiak bears.
The brown bear is a naturally long-lived animal. The average lifespan in the wild is about 25 years. The oldest wild brown bear on record was nearly 37 years old. The oldest brown bear in captivity have been verified to live up to 47 years, with one captive male possibly attaining 50 years of age.
The brown bear is one of the two largest terrestrial carnivorans alive today, rivaled in body size only by its close cousin, the polar bear (Ursus maritimus), which is much less variable in size and averages larger due to this.
The size of brown bears is the most variable of modern bears. The typical size depends upon which population it is from, and most accepted races vary widely in size.
The normal range of physical dimensions for a brown bear is a head-and-body length of 1.4 to 2.8 m (4 ft 7 in to 9 ft 2 in) and a shoulder height of 70 to 153 cm (2 ft 4 in to 5 ft 0 in).
Adults have massive, heavily built concave skulls, which are large in proportion to the body.
The tail is relatively short, as in all bears, ranging from 6 to 22 cm (2.4 to 8.7 in) in length.
The average weight of adult male bears from 19 populations, from around the world and various subspecies (including both large and small bodied subspecies), was found to 217 kg (478 lb) while adult females from 24 populations were found to average 152 kg (335 lb).
The largest subspecies are the Kodiak bear (Ursus arctos middendorffi), commonly reaches sizes of 300 to 600 kg (660 to 1,320 lb), and has even been known to exceed weights of 680 kg (1,500 lb) on occasion.
Brown bears are often not fully brown. Brown bears have long, thick fur, with a moderately long mane at the back of the neck which varies somewhat across the races. In India, brown bears can be reddish with silver tips, while in China, brown bears are bicolored with a yellow-brown or whitish cape across the neck, chest, and shoulders. North American grizzlies can be dark brown (almost black) to cream (almost white) or yellowish brown and often have darker colored legs.
One thing all brown bears around the world have in common is a hump of muscle on their back between the shoulders. Combined with huge paws and long front claws, the muscles make these animals powerful diggers.
Brown bears have very large and curved claws, those present on the forelimbs being longer than those on the hind limbs. They may reach 5 to 6 centimeters (2.0 to 2.4 in) and may measure 7 to 10 centimeters (2.8 to 3.9 in) along the curve. The rear feet of adult bears have been found to typically measure 21 to 36 cm (8.3 to 14.2 in) long, while the forefeet tend to measure about 40% less in length.
Due to their claw structure, in addition to their excessive weight, adult brown bears cannot typically climb trees as can both species of black bear, although in rare cases adult female brown bears have been seen in trees.
Despite their enormous size, brown bears are extremely fast, having been clocked at speeds of 50 kilometers (30 miles) per hour.
The home range of a brown bear is extremely large, reaching up to 2,000 square kilometers (770 square miles) in males, however they are not highly territorial.
The brown bear is often described as nocturnal. However, it frequently seems to peak in activity in the morning and early evening hours. Studies have shown that activity throughout the range can occur at nearly any time of night or day, with bears who dwell in areas with more extensive human contact being more likely to be fully nocturnal.
Brown bears tend to be solitary animals, except for females and their cubs; although they may gather in large numbers at major food sources (e.g., moth colonies, open garbage dumps or rivers holding spawning salmon). In these cases, a dominance hierarchy involving aggression is established. While it is large adult males that are the highest-ranking, the most aggressive individuals are females that have young.
Brown bears are omnivorous. Most brown bears are not highly carnivorous, as they derive up to 90% of their dietary food energy from vegetable matter. Their diet varies with the season – from grass and shoots in the spring to berries and apples in the summer, nuts and plums in autumn. All year round they eat roots, insects, mammals, fish, reptiles, and of course, honey.
In the Kamchatka peninsula and several parts of coastal Alaska, including Kodiak Island, brown bears feed largely on spawning salmon, whose nutrition and abundance explain the enormous size of the bears in these areas.
In fall a brown bear may eat as much as 40 kilograms (90 pounds) of food each day, and it may weigh twice as much before hibernation as it will in spring.
Brown bears hibernate throughout winter, preserving energy by reducing heart rate and body temperature by a few degrees. Hibernation takes place in a den, often dug into a sheltered slope, in which the bear may survive for over half a year without eating, drinking, urinating or defecating
Brown bears mate from May to July, and a gestation of 180 to 266 days follows, with births occurring from January to March, usually while the female is still in hibernation. She generally lays down two to three offspring, and breeds again 2 to 4 years later.
Young born bears are vulnerable, being blind, naked and weighing only 350 to 510 g (0.77 to 1.12 lb). They feed on their mother’s milk until spring or even early summer, depending on climate conditions. Cubs remain with their mother for some two and a half years.
While the brown bear’s range has shrunk and it has faced local extinctions, it remains listed as a least concern species by the International Union for Conservation of Nature (IUCN).
There are approximately 200,000 brown bears left in the world. The largest populations are in Russia with 120,000, the United States with 32,500, and Canada with around 25,000.
Brown bears can be dangerous to humans, particularly if surprised or if a person gets between a mother bear and her cubs.
Native American tribes sympatric with brown bears often view them with a mixture of awe and fear.
Brown bears often figure into the literature of Europe and North America, in particular that which is written for children.