Brown bear

The brown bear (Ursus arctos) is a large bear native to Eurasia and North America. Of the land carnivorans, it is rivaled in size only by its closest relative, the polar bear, which is much less variable in size and slightly bigger on average. The brown bear is a sexually dimorphic species, as adult males are larger and more compactly built than females. The fur ranges in color from cream to reddish to dark brown. It has evolved large hump muscles, unique among bears, and paws up to 21 cm (8.3 in) wide and 36 cm (14 in) long, to effectively dig through dirt. Its teeth are similar to those of other bears and reflect its dietary plasticity.

Throughout the brown bear's range, it inhabits mainly forested habitats in elevations of up to 5,000 m (16,000 ft). It is omnivorous, and consumes a variety of plant and animal species. Contrary to popular belief, the brown bear derives 90% of its diet from plants. When hunting, it will target animals as small as insects and rodents to those as large as moose or muskoxen. In parts of coastal Alaska, brown bears predominantly feed on spawning salmon that come near shore to lay their eggs. For most of the year, it is a usually solitary animal that associates only when mating or raising cubs. Females give birth to an average of one to three cubs that remain with their mother for 1.5 to 4.5 years. It is a long-lived animal, with an average lifespan of 25 years in the wild. Relative to its body size, the brown bear has an exceptionally large brain. This large brain allows for high cognitive abilities, such as tool use. Attacks on humans, though widely reported, are generally rare.

While the brown bear's range has shrunk, and it has faced local extinctions across its wide range, it remains listed as a least concern species by the International Union for Conservation of Nature (IUCN) with a total estimated population in 2017 of 110,000. Populations that were hunted to extinction in the 19th and 20th centuries are the Atlas bear of North Africa and the Californian, Ungavan and Mexican populations of the grizzly bear of North America. Many of the populations in the southern parts of Eurasia are highly endangered as well. One of the smaller-bodied forms, the Himalayan brown bear, is critically endangered: it occupies only 2% of its former range and is threatened by uncontrolled poaching for its body parts. The Marsican brown bear of central Italy is one of several currently isolated populations of the Eurasian brown bear and is believed to have a population of only about 50 bears.

The brown bear is considered to be one of the most popular of the world's charismatic megafauna. It has been kept in zoos since ancient times, and has been tamed and trained to perform in circuses and other acts. For thousands of years, the brown bear has had a role in human culture, and is often featured in literature, art, folklore, and mythology.

The brown bear is sometimes referred to as the bruin, from Middle English. This name originated in the fable History of Reynard the Fox, translated by William Caxton, from the Middle Dutch word bruun or bruyn, meaning "brown". In the mid-19th-century United States, the brown bear was given the nicknames "Old Ephraim" and "Moccasin Joe".

The scientific name of the brown bear, Ursus arctos, comes from the Latin ursus, meaning "bear", and the Greek ἄρκτος/arktos, also meaning "bear".

Carl Linnaeus scientifically described the species under the name Ursus arctos in the 1758 edition of Systema Naturae. Brown bear taxonomy and subspecies classification has been described as "formidable and confusing", with few authorities listing the same set of subspecies. There are hundreds of obsolete brown-bear subspecies. As many as 90 subspecies have been proposed. A 2008 DNA analysis identified as few as five main clades, which comprise all extant brown bear species, while a 2017 phylogenetic study revealed nine clades, including one representing polar bears. As of 2005^[update], 15 extant, or recently extinct, subspecies were recognized by the general scientific community.

DNA analysis shows that, apart from recent, human-caused population fragmentation, brown bears in North America are generally part of a single interconnected population system, with the exception of the population (or subspecies) in the Kodiak Archipelago, which has probably been isolated since the end of the last Ice Age. These data demonstrate that U. a. gyas, U. a. horribilis, U. a. sitkensis, and U. a. stikeenensis are not distinct or cohesive groups, and would more accurately be described as ecotypes. For example, brown bears in any particular region of the Alaska coast are more closely related to adjacent grizzly bears than to distant populations of brown bears.