Brown Bear

The **brown bear** (*Ursus arctos*) is a bear that is found across much of northern Eurasia and North America. It is one of the largest living terrestrial members of the order Carnivora, rivaled in size only by its closest relative, the polar bear (*Ursus maritimus*), which is much less variable in size and slightly larger on average.

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. The brown bear is recognized as a national and state animal in several European countries.

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) with a total population of approximately 200,000. As of 2012, this and the American black bear are the only bear species not classified as threatened by the IUCN. However, the Californian, North African and Mexican subspecies were hunted to extinction in the nineteenth and early twentieth centuries and many of the southern Asian subspecies are highly endangered. One of the smaller-bodied subspecies, the Himalayan brown bear, is critically endangered, occupying only 2% of its former range and threatened by uncontrolled poaching for its parts. The Marsican brown bear, one of several currently isolated populations of the main Eurasian brown bear population, in central Italy is believed to have a population of just 30 to 40 bears.

## Description

Adults have massive, heavily built concave skulls, which are large in proportion to the body. The forehead is high and rises steeply. The projections of the skull are well developed when compared to those of Asian black bears (*Ursus thibetanus*): the latter have sagittal crests not exceeding more than 19–20% of the total length of the skull, while the former have sagittal crests comprising up to 40–41% of the skull's length. Skull projections are more weakly developed in females than in males. The braincase is relatively small and elongated. There is a great deal of geographical variation in the skull, and presents itself chiefly in dimensions. Grizzlies, for example, tend to have flatter profiles than European and coastal American brown bears. Skull lengths of Russian bears tend to be 31.5 to 45.5 centimetres (12.4 to 17.9 in) for males, and 27.5 to 39.7 centimetres (10.8 to 15.6 in) for females. The width of the zygomatic arches in males is 17.5 to 27.7 centimetres (6.9 to 11 in), and 14.7 to 24.7 centimetres (5.8 to 9.7 in) in females. Brown bears have very strong teeth: the incisors are relatively big and the canine teeth are large, the lower ones being strongly curved. The first three molars of the upper jaw are underdeveloped and single crowned with one root. The second upper molar is smaller than the others, and is usually absent in adults. It is usually lost at an early age, leaving no trace of the alveolus in the jaw. The first three molars of the lower jaw are very weak, and are often lost at an early age. The teeth of brown bears reflect their dietary plasticity and are broadly similar to other bears excluding the two most herbivorous living bears, the giant panda (*Ailuropoda melanoleuca*) and spectacled bear (*Tremarctos ornatus*), which have blunt, small premolars (ideal for grinding down fibrous plants) compared to the jagged premolars of ursid bears that at least seasonally often rely on flesh as a food source. The teeth are reliably larger than American black bears but average smaller in molar length than polar bears. Brown bears have the broadest skull of any extant ursine bear, only the afforementioned most herbivorous living bears exceed them in relative breadth of the skull. Another extant ursine bear, the sloth bear(*Melursus ursinus*), has a proportionately longer skull than the brown bear and can match the skull length of even large brown bear subtypes, presumably as an aid for foraging heavily on insect colonies for which a long muzzle is helpful as an evolved feature in several unrelated mammalian groups.

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