Temporal range: 0.5–0 Ma Middle Pleistocene-Holocene
|Alaska Peninsula brown bear in Hallo Bay, Katmai National Park, Alaska|
16, see text
|Brown bear range map|
The brown bear (Ursus arctos) is a large bear with the widest distribution of any living ursid. The species is distributed across much of northern Eurasia and North America. It 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. There are several recognized subspecies, many of which are quite well-known within their native ranges, found in the brown bear species.
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 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 (Atlas bear), 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 race, in central Italy is believed to have a population of just 30 to 40 bears.
- 1 Evolution and taxonomy
- 2 Description
- 3 Distribution and habitat
- 4 Conservation status
- 5 Behavior
- 6 Home ranges
- 7 Reproduction
- 8 Longevity and mortality
- 9 Dietary habits
- 10 Relationship with humans
- 11 Legal status
- 12 Potential Maximum Size
- 13 See also
- 14 References
- 15 Bibliography
- 16 External links
Evolution and taxonomy
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 Middle Dutch bruun or bruyn, meaning brown (the color). In the mid-19th century United States, the brown bear was termed "Old Ephraim" and sometimes as "Moccasin Joe".
Generalized brown bear names and evolution
Brown bears are thought to have evolved from Ursus etruscus in Asia. The brown bear, per Kurten (1976), has been stated as "clearly derived from the Asian population of Ursus savini about 800,000 years ago; spread into Europe, to the New World." A genetic analysis indicated that the brown bear lineage diverged from the cave bear species complex approximately 1.2-1.4 million years ago but did not clarify if U. savini persisted as a paraspecies for the brown bear before perishing. The oldest fossils positivity identified as from this species occur in China from about 0.5 million years ago. Brown bears entered Europe about 250,000 years ago, and North Africa shortly after. Brown bear remains from the Pleistocene period are common in the British Isles, where it is thought they might have outcompeted cave bears (Ursus spelaeus). The species entered Alaska 100,000 years ago, though they did not move south until 13,000 years ago. It is speculated that brown bears were unable to migrate south until the extinction of the much larger Arctodus simus.
Several paleontologists suggest the possibility of two separate brown bear migrations: inland brown bears, also known as grizzlies, are thought to stem from narrow-skulled bears which migrated from northern Siberia to central Alaska and the rest of the continent, while Kodiak bears descend from broad-skulled bears from Kamchatka, which colonized the Alaskan peninsula. Brown bear fossils discovered in Ontario, Ohio, Kentucky and Labrador show the species occurred farther east than indicated in historic records. In North America, two types of the subspecies Ursus arctos horribilis are generally recognized—the coastal brown bear and the inland grizzly bear; these two types broadly define the range of sizes of all brown bear subspecies.
Scientific brown bear taxonomy
There are many methods used by scientists to define bear species and subspecies as no one method is always effective. Brown bear taxonomy and subspecies classification has been described as “formidable and confusing” with few authorities listing the same specific set of subspecies. Genetic testing is now perhaps the most important way to scientifically define brown bear relationships and names. Generally genetic testing uses the word clade rather than species because a genetic test alone cannot define a biological species. Most genetic studies report on how closely related the bears are (or their Genetic distance). There are hundreds of obsolete brown bear subspecies, each with its own name, and this can become confusing; Hall (1981) lists 86 different types and even as many as 90 have been proposed. However, recent DNA analysis has identified as few as five main clades which contain all extant brown bears. As of 2005, 16 living global subspecies are recognized by the general scientific community.
As well as the exact number of overall brown bear subspecies, its precise relationship to the polar bear also remains in debate. The polar bear is a recent offshoot of the brown bear. The point at which the polar bear diverged from the brown bear is unclear with estimations based on genetics and fossils ranging from 400,000 to 70,000 years ago, but most recent analysis has indicated that the polar split somewhere between 250,000 and 130,000 years ago. Under some definitions, the brown bear can be construed as the paraspecies for the polar bear. DNA analysis recently revealed that the brown bears in North America are genetically quite homogeneous except for the one subspecies Kodiak bear and the enigmatic ABC Islands Bears that have the mtDNA of the polar bear (Ursus maritimus).
The subspecies have been listed as follows:
|Ursus arctos arctos – Eurasian brown bear||Represents every population found in Europe as well as their range in western Russia and the Caucasus. May be found as far east in Russia as the Yenisei River in Yamalo-Nenets Autonomous Okrug to Novosibirsk Oblast in the south, where bears grade into U. a. collaris.||A predominantly dark, richly brown-colored (with rare light-colored individuals), moderately sized subspecies with dark claws, the Eurasian browns occurring in Russia are larger than their European counterparts, which may be in part because they are hunted less.|
|Ursus arctos beringianus – Kamchatka brown bear (or Far Eastern brown bear)||Found in the coastal lands surrounding the Sea of Okhotsk down as far as Shantar Islands, Kolyma, all land around the Shelikhov Gulf, the Kamchatka Peninsula and Paramushir Island.||A very large bear with a broad muzzle. Overall has dark coloring, some animals appearing almost blackish-brown but will usually be paler at the top of the back. It may overlap with U. a. collaris extensively a few miles inland. It is thought to be the ancestor of the polar bear and the Kodiak bear. and the Peninsular brown bears of Alaska. Middendorf described it from Greater Shantar Island with its distribution range comprising the eastern coast of Siberia and Japan.|
|Ursus arctos collaris – East Siberian brown bear||A majority of Siberia from the Yenisei River to as far south as the Altai Mountains in northern Mongolia, northermost Xinjiang and northeastern Kazakhstan. Ranges as far north as southwestern Taymyr Peninsula and Anabar River. As far east ranging of all Eurasian brown bear races, it is found in Chukotka as far as the coast of the Bering Strait to the east and the coast of the Chukchi Sea in the north.||Most bears of this race are fairly dark but some are as pale as grizzly bears. It is intermediate in size between U. a. arctos and U. a. beringianus, with a proportionately larger skull than the nominate subspecies. In the sub-Arctic region of Yakutia, bears are reportedly quite small compared to other regions.|
|Ursus arctos crowtheri – †Atlas bear (extinct)||Habitat while still extant was the Atlas Mountains and adjacent areas in North Africa, from Morocco to Libya.||Last surviving bear is thought to have been killed by hunters in 1890.|
|Ursus arctos isabellinus – Himalayan brown bear||Northern Nepal, Northern and Northeastern India, and Northern Pakistan, most continuous current range in Jammu and Kashmir.||Quite distinctive physically, as it possess a reddish-brown or sandy coat color and relatively large ears. This bear is smaller than most other brown bears found on the Asian continent. Prefers high altitude forest and alpine meadow. Critically Endangered.|
|Ursus arctos pruinosus – Tibetan blue bear||Tibetan plateau, some of the bears found in the Himalayas are reportedly actually wandering individuals from the more robustly populated Tibetan subspecies.||This is a moderately sized subspecies with long and shaggy fur. Both dark and light variants are encountered, with intermediate colors predominating. The fur around the neck is light, and frequently forms a "collar" which no other brown bear possess in a mature state. Like the Himalayan brown bear, the ears are relatively prominent. The skull is distinguished its relatively flattened choanae, an arch-like curve of the molar row and large teeth.|
|Ursus arctos lasiotus – Ussuri brown bear (or Amur brown bear, black grizzly or horse bear)||Russia: Southern Kuril Islands, Sakhalin, Maritime territory, and the Ussuri/Amur River region south of the Stanovoy Range, China (former Manchuria): Heilongjiang, Japan: Hokkaidō, Honshu (last glacial period), Korean Peninsula: North Korea Became extinct on Rebun and Rishiri Islands in 13th century.||Ursus arctos lasiotus is quite variable in size. Skull dimensions from mainland Russia (i.e. Primorsky and Khabarovsk) indicate they can rival Kamchatka brown bears in size. On the contrary, the population found in Hokkaido is one of the smallest northern form of brown bears. Nonetheless, individuals from Hokkaido can reportedly get larger than expected and have reached 400 to 550 kg (880 to 1,210 lb). in weight by feeding on cultivations. This bear is thought to be the ancestor of U. a. horribilis. It is perhaps the darkest colored race on average and some specimens are almost fully black in colour, although lighter brown and intermediate forms are known. Due its coloring, this race is sometimes informally referred to as the “black grizzly”.|
|Ursus arctos syriacus – Syrian brown bear||Transcaucasia, Iraq, Turkey (Asia Minor), Iran, western Afghanistan, Pakistan, western Himalayas and the Pamir-Alay and Tien Shan mountains, Despite historical presence in Israel and the Syrian Arab Republic (the races’ namesake), it is believed to extinct in these countries now.||The Syrian is a moderate to small-sized subspecies with light claws. This race tends to be an whitish blond color without less noticeable black-based hairs than grizzly bears have.|
|Ursus arctos alascensis – Alaska brown bear||Northern Alaska||Generally still recognized but may be considered inclusive with U. a. horribilis.|
|Ursus arctos californicus – †California grizzly (extinct)||California, mainly in Sierra Nevadas and some areas of coastal California.||The last known bear was shot in California in 1922. Museum specimens illustrate that this race was golden-blonde overall typically without the contrasting black fur base of true grizzly bears. It also appeared to have been considerably larger with a broader muzzle than true grizzly bears.|
|Ursus arctos dalli – Dall Island brown bear||Dall Island of Alaska.||Poorly described, possibly merely a coastal variation of other North American bears but any such alliance is genetically ambiguous.|
|Ursus arctos horribilis – Grizzly bear||Most of the historic and present North American range including the entire range in both Northern and Western Canada (arguably excluding British Columbia), most of Alaska, excluding the coastal reaches, and the northwestern United States, historically also existed in Great Plains.||Grizzlies are identified by a medium to dark brown coat with gray or blond "grizzled" tips on the fur which contrast with the black base. Highly variable in size based largely on environmental conditions. Also it is highly adaptable: it can live in montane pine forests, temperate rainforest, semi-arid scrubland, tundra and shortgrass prairie.|
|Ursus arctos middendorffi – Kodiak bear||Kodiak, Afognak, Shuyak Islands (Alaska), arguably includes other coastal Alaskan forms, which occur in most of the coasts of the western and southern parts of the state.||This is the largest distinct subspecies of brown bear, though the coastal-living members of other brown bear subspecies potentially rivaling it in size. It is medium-hued, typically not as dark as most forms from eastern Asia but distinctly darker than grizzly bears.|
|Ursus arctos nelsoni – †Mexican grizzly bear (extinct)||The smallest North American brown bear, formerly from northern Mexico, including Chihuahua, Coahuila, and Sonora, southwestern United States including southern ranges of Texas, Arizona, and New Mexico||This bear is believed to have been hunted to extinction due to its interference with cattle ranching in both the United States and Mexico. Scarce by the 1930s, the last recorded sighting was in 1962. Distinct in its ability to survive arid conditions, it could live in both montane pine forests of Mexico and canyonlands of adjacent to the Sonoran Desert.|
|Ursus arctos sitkensis||Admiralty Island, Baranof Island, and Chichagof Island the ABC Islands of Alaska.||Appearing to be more closely related to the polar bear than to other brown bears although it is on average the most dark-colored race in North America, with similar body size to grizzly bears from interior Alaska. This subspecies is called "clade II" by Waits, and others, and is part of the former subspecies identified as U. a. sitkensis, by Hall and as U. a. dalli by Kurtén.|
A grizzly–polar bear hybrid (known as a pizzly bear or grolar bear) 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).
Analyses of the genomes of bears have recovered multiple instances of introgressive hybridization between various bear species, including introgression of polar bear DNA intro brown bears during the Pleistocene.
Formerly considered subspecies
|Ursus arctos marsicanus – Marsican brown bear or Apennine brown bear||Marsica, central Italy||There are an estimated 30 to 40 bears remaining in the Marsica area. This is an unrecognized subspecies that is considered to be a member of the nominate subspecies.|
|Ursus arctos pyrenaicus – Iberian brown bear, sometimes called Cantabrian brown bear, now considered Ursus arctos arctos – Eurasian brown bear||See photographs in Eroski article (in Spanish, also available in Catalan, Basque and Galician) and in Fauna Ibérica. Oso pardo ibérico (Ursus arctos pyrenaicus), in Spanish||Iberian Peninsula, primarily the Cantabrian Mountains and hills in Galicia, and the Pyrenees||Until recently, this bear was considered a separate subspecies. Today, it is considered to belong to the U. arctos arctos subspecies. Scientific evidence based on DNA studies would furthermore indicate the Eurasian brown bear can be divided into two distinct lineages. "There is a clear division into two main mitochondrial lineages in modern Eurasian brown bear populations. These populations are divided into those carrying an eastern lineage (clade IIIa, Leonard et al. 2000), which is composed of Russian, northern Scandinavian and eastern European populations, and those carrying a western lineage (clade I, Leonard et al. 2000), which is composed of two subgroups, one believed to originate from the Iberian Peninsula, including southern Scandinavian bears and the Pyreneean populations; and the other from the Italian–Balkan peninsulas (Taberlet et al. 1994; see however Kohn et al. 1995). In addition, based on the subfossil record in northwestern Moldova and mitochondrial DNA data from modern populations, a Carpathian refuge has also been proposed (Sommer & Benecke 2005; Saarma et al. 2007)."
The brown bear is the largest wild animal on the Iberian Peninsula, although one of the smallest of the brown bears, weigh between 92 and 180 kg (203 and 397 lb) as adults. Their fur varies from a pale cream color to dark brown, but always with a distinctively darker, nearly black tone at the paws and a yellowish tinge at the tip of each hair. The brown bear population is considered endangered in Spain.
|Ursus arctos gobiensis – Gobi bear||Gobi Desert||The taxonomic alliance of these extremely rare bears found in the Gobi desert are unclear. They’ve been allied with both the east Siberian brown bear, which is found in northern Mongolia somewhat north of the Gobi desert, and the Tibetan blue bear, with which it is most often considered synonymous is distributed hundreds of miles to the south. At one time, Gobi bears probably overlapped and possibly interbreed with Tibetan bears in western China but the species is now extinct in this area. The Gobi bear is adapted to desert dwelling, dwelling in oases and rocky outcrops. It is rather small and pale and it appears to lack the whitish collar characteristic of Tibetan bears.|
|Ursus arctos gyas – Alaska Peninsula brown bear||Coastal Alaska from the Aleutian islands as far west as Unimak, the Alaska Peninsula to the Kenai Peninsula.||Considered by some biologists to be same subspecies as U. a. middendorffi. Based on known size of adult males, if a true subspecies, it may match or exceed the Kodiak bear in size.|
|Ursus arctos stikeenensis – Stikine brown bear||Northwestern British Columbia From the Stikine River to the Skeena River.||Considered by biologists to be part of the race U. a. horribilis, it once was thought a subspecies. Larger than most other grizzly bear populations, with male sizes approaching the great bears of coastal Alaska.|
Color of brown bears
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 shoulders. North American grizzlies can be dark brown (almost black) to cream (almost white) or yellowish brown. The common name grizzly stems from their typical coloration, with their hairs usually being brownish-black at the base and whitish-cream at the tips, giving them their distinctive “grizzled” color. The winter fur is very thick and long, especially in northern subspecies, and can reach 11 to 12 centimetres (4 to 5 in) at the withers. The winter hairs are thin, yet rough to the touch. The summer fur is much shorter and sparser, and its length and density varies geographically.
Claws and feet
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 centimetres (2.0 to 2.4 in) and may measure 7 to 10 centimetres (2.8 to 3.9 in) along the curve. They are generally dark with a light tip, with some forms having completely light claws. Brown bear claws are longer and straighter than those of American black bears (Ursus americanus). The claws are blunt, while those of a black bear are sharp. 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. The claws of a polar bear are also quite different, being notably shorter but broader with a strong curve and sharper point, presumably both as an aid to traveling over ice (sometimes nearly vertically) and procuring active prey. The paws of the brown bear are quite large. 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. All four feet in average sized brown bears tend to be about 17.5 to 20 cm (6.9 to 7.9 in) in width. In large coastal or Kodiak bear males, the hindfoot may measure up to 40 cm (16 in) in length, 28.5 cm (11.2 in) in width, while outsized Kodiak bears having having had confirmed measurements of up to 46 cm (18 in) along their rear foot. Brown bears are the only extant bears with a hump at the top of their shoulder, which are made entirely of muscle, this feature having developed presumably for imparting more force in digging, which is habitual during foraging for most bears of the species and also used heavily in den construction prior to hibernation.
Cranial morphology and size
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 races, 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.
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. This is in part due to sexual dimorphism as male brown bears which average at least 30% larger in most races. Additional variability in size is complicated by seasonal variations in body mass: the spring low weights, which are lowest in newly active bears due to lack of foraging during hibernation, are always much lower than fall weights. Due to autumn hypophagia, bears put on additional weight to prepare for hibernation and continued rapid weight increases every year are not infrequently recorded in adult bears, particularly males, in the years following maturity. Therefore, a bear may need to be weighed in both spring and fall to get an idea of its mean annual weight. 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). The tail is relatively short, as in all bears, ranging from 6 to 22 cm (2.4 to 8.7 in) in length. The smallest brown bears, females during spring among barren-ground populations, can weigh so little as to roughly match the body mass of males of the smallest living bear species, the sun bear (Helarctos malayanus), while the largest coastal races attain sizes broadly similar to those of the largest living bear species, the polar bear. Interior brown bears are generally smaller than is often perceived, being around the same weight as an average African lion (Panthera leo leo) at an estimate average of 180 kg (400 lb) in males and 135 kg (298 lb) in females, whereas adults of the coastal races weigh about twice as much. 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).
Ecotype or regional populations
Brown bear size, most often measured in body mass, is highly variable and is correlated to extent of food access. Therefore, bears who range in ecozones that include have access to openings, cover and moisture or water tend to average larger whereas those bears that range into ecozones with enclosed forested areas or arid, sparsely vegetated regions, both of which tend to be sub-optimal foraging habitat for brown bears, average smaller. The brown bear in northern Europe (i.e. Scandinavia, eastern Europe, western Russia), Yellowstone National Park or interior Alaska seasonally weigh on average between 115 and 360 kg (254 and 794 lb), from mean low adult female weights in spring to male bear mean high weights in fall. Bears from the Yukon Delta, interior British Columbia, Jasper National Park and southern Europe (i.e. Spain, the Balkans) can weigh from 55 to 175 kg (121 to 386 lb) on average. These mass variations represent only two widespread subspecies, the grizzly bear in North America, and the Eurasian brown bear in Europe. Due to the lack of genetic variation within subspecies, the environmental conditions in a given area likely plays the largest part in such weight variations.
The grizzly is especially variable in size, as grizzlies from the largest populations, i.e. interior Alaska, with the heaviest weights recorded in Nelchina, Alaska, nearly three times heavier in males than the smallest grizzlies from Alberta, Canada’s Jasper National Park. Between the sexes, the grizzlies of Nelchina average around 207 kg (456 lb), whereas the Jasper grizzlies averaged about 74 kg (163 lb). The enclosed taiga habitat of Jasper presumably is sub-optimal foraging habitat for grizzlies, requiring them to range widely and feed sparsely, thus reducing body weights and putting bears at risk of starvation, while in surfaces areas in the tundra and prairie are apparently ideal for feeding. Even elsewhere in the Alberta province, weights averaging more than twice those of Jasper grizzlies have been recorded. A gradual diminishment in body size is noted in grizzly bears from the sub-Arctic zone, from the Brooks Range to the Mackenzie Mountains, presumably because food becomes much sparser in such regions, although perhaps the most northerly recorded grizzly bears ever, in the Northwest Territories, was a large and healthy male weighing 320 kg (710 lb), more than twice as much as an average male weighs near the Arctic Circle. Data from Eurasia similarly indicates a diminished body mass in sub-Arctic brown bears, based on the weights of bears from northern Finland and Yakutia.
Head-and-body length in grizzly bears averages from 1.8 to 2.13 m (5 ft 11 in to 7 ft 0 in) while in Eurasian brown bears it similarly averages from 1.7 to 2.1 m (5 ft 7 in to 6 ft 11 in). Adult shoulder height averaged 95.2 cm (3 ft 1 in) in Yellowstone (for any bear measured five or more years old) and a median of 98.5 cm (3 ft 3 in) (for adults only 10 or more years old) in Slovakia. Standing on its hindlegs, a posture only assumed occasionally, typically sized brown bears can reportedly range from 1.83 to 2.75 m (6 ft 0 in to 9 ft 0 in) in standing height. Exceptionally large inland specimens have been reported in several parts of North America, Europe, Russia and even Hokkaido. The largest recorded grizzlies from Yellowstone and Washington state both weighed approximately 500 kg (1,100 lb) and eastern European bears have been weighed in Slovakia and Bulgaria of up to 400 kg (880 lb), about double the average weight for male bears in these regions. Among the grizzly and Eurasian brown bear subspecies, the largest reportedly shot from each being 680 kg (1,500 lb) and 481 kg (1,060 lb), respectively. The latter bear, from western Russia, reportedly measured just under 2.5 m (8 ft 2 in) in head-and-body length.
In Eurasia, the size of bears roughly increases from the west to the east, with the largest bears there native to eastern Russia. Even in the nominate subspecies size increases in the eastern limits, with mature male bears in Arkhangelsk Oblast and Bashkortostan commonly exceeding 300 kg (660 lb). Other bears of intermediate size may occur in inland races of Russia. Much like the grizzly and Eurasian brown bear, populations of the Ussuri brown bear (U. a. lasiotus) and the East Siberian brown bear (U. a. collaris) may vary widely in size. In some cases, the big adult males of these races may have matched the Kodiak bear in size. East Siberian brown bears from outside the sub-Arctic and mainland Ussuri brown bears average about the same size as the largest-bodied populations of grizzly bear, i.e. those of similar latitude in Alaska, and have been credited with weights ranging from 100 to 400 kg (220 to 880 lb) throughout the seasons. On the other hand, the Ussuri brown bears found in the insular population of Hokkaido are usually quite small, usually weighing less than 150 kg (330 lb), exactly half the weight reported for male Ussuri brown bears from Khabarovsk Krai. This is due presumably to the enclosed mixed forest habitat of Hokkaido. A similarly diminished size has been reported in east Siberian brown bears from Yakutia, as even adult males average around 145 kg (320 lb), thus about 40% less than the average weight of male bears of this race from central Siberia and the Chukchi Peninsula.
In linear measurements and mean body mass, several subspecies may vie for the title of smallest race, although thus far their reported body masses broadly overlaps with those of the smaller-bodied populations of Eurasian brown and grizzly bears. Leopold (1959) described the now extinct Mexican grizzly that, according to Rausch (1963), as the smallest race of grizzly bear in North America although the exact parameters of its body size are not known today. Bears from the Syrian (U. a. syriacus) subspecies will reportedly weigh around 100 to 160 kg (220 to 350 lb) in adulthood. The Himalayan race (U. a. isabellinus) is another rival for smallest subspecies, in Pakistan this race averages about 70 kg (150 lb) in females and 135 kg (298 lb) in males. Himalayan brown bear females were cited with an average head-and-body length of merely 1.4 m (4 ft 7 in). Brown bears of the compact Gobi Desert population, which is not usually listed as a distinct subspecies in recent decades, weigh around 90 to 138 kg (198 to 304 lb) between the sexes so are similar in weight to bears from the Himalayas and even heavier than grizzlies from Jasper National Park. However, the Gobi bear has been reported to measure as small as 1 m (3 ft 3 in) in head-and-body length, which if accurate would make them the smallest known brown bear in linear dimensions. These smallest brown bear races are characteristically found in “barren ground” type habitats, i.e. sub-desert in bears from the Syrian and Gobi races and arid alpine meadow in Himalayan bears.
The largest subspecies are the Kodiak bear (U. a. middendorffi) and the questionably distinct peninsular or coastal brown bear (U. a. gyas). Also the extinct California grizzly (U. a. californicus) was rather large. Once mature, the typical female Kodiak bear can range in body mass from 120 to 318 kg (265 to 701 lb) and while from sexual maturity onward male ranges from 168 to 675 kg (370 to 1,488 lb). According to Guinness Records the average male Kodiak bear is 2.44 m (8 ft 0 in) in total length (head-to-tail) and has a shoulder height of 1.33 m (4 ft 4 in). When averaged between their spring low and fall high weights from both localities, males from Kodiak island and coastal Alaska weighed from 312 to 389 kg (688 to 858 lb) with a mean body mass of 357 kg (787 lb) while the same figures in females were 202 to 256 kg (445 to 564 lb) with a mean body mass of 224 kg (494 lb). By the time they reach or exceed eight to nine years of age, male Kodiak bears tend to be much larger than newly mature 6-year-old males, potentially tripling their average weight within three years’ time, and can expect to average between 360 and 545 kg (794 and 1,202 lb). The reported mean adult body masses for both sexes of polar bear are very similar to the peninsular and Kodiak bears. Due to their roughly corresponding body sizes, the two races and the species can both legitimately be considered the largest living member of the bear family Ursidae and largest extant terrestrial carnivores.
The largest variety of brown bear from Eurasia is the Kamchatka brown bear (U. a. beringianus). In the Kamchatka brown bear in past decades, old males have been known to reach body mass of 500–685 kg (1,102–1,510 lb) by fall, putting the race well within Kodiak bear sizes and leading it to be considered the largest of the extant Russian races. However, a diminishment in body size of U.a. berigianus has been noted, mostly likely in correlation with overhunting. In the 1960s and 1970s, most adult Kamchatka brown bears weighed merely between 150 and 285 kg (331 and 628 lb), however mean weights of mature male bears has been reported as averaging 350 to 450 kg (770 to 990 lb) in 2005.
Distribution and habitat
Brown bears were once native to much of Asia, some parts of the Atlas Mountains of Africa and perhaps most of Europe and North America, but are now extinct in some areas, and their populations have greatly decreased in other areas. 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.The brown bear currently occurs in the countries of Afghanistan, Albania, Andorra (recently reoccupied), Armenia, Azerbaijan, Belarus, Bhutan (possibly extinct), Bosnia and Herzegovina, Bulgaria, Canada, China, Croatia, Czech Republic (possibly only vagrants), Estonia, Finland, France, Georgia, Greece, India, Iran, Iraq, Italy, Japan, Kazakhstan, Kyrgyzstan, Latvia (extinct before WWII; possibly vagrants from Estonia or Russia after WWII), Republic of Macedonia, Mongolia, Montenegro, Nepal, North Korea, Norway, Pakistan, Poland, Romania, Russia, Serbia, Slovakia, Slovenia, Spain, Sweden, Tajikistan, Turkey, Turkmenistan, Ukraine, the United States, and Uzbekistan.
As many as 20,000 brown bears range throughout the Yukon, Northwest Territories, and British Columbia, and in the majority of Alberta. Canada has one of the most stable brown bear populations today. They reach their current eastern limits of their distribution in North America in a majority of Nunavut, northeastern Saskatchewan and northern Manitoba, where they range as far east as the west coast of the Hudson Bay from around Rankin Inlet south to Southern Indian Lake.
The brown bear has lost 98% of its habitat in the lower 48 states. About 95% of the brown bear population in the United States is in Alaska, though in the lower 48 states, they are repopulating gradually but steadily along the Rockies and the western Great Plains. The Alaskan population is estimated at 32,000 individuals. The largest populations of brown bears in the lower 48 states are found in the 23,300-km2 Greater Yellowstone Ecosystem and the 24,800-km2 Northern Continental Divide Ecosystem. The Greater Yellowstone Ecosystem of northwest Wyoming is estimated to hold about about 674–839 grizzly bears, followed slightly the Northern Continental Divide Ecosystem of northwest Montana with about 765 animals, the Cabinet-Yaak Ecosystem of northwest Montana and northeast Idaho with about 42-65 bears of the species, the Selkirk Ecosystem of northeast Washington and northwest Idaho with only about 40–50 animals and even less the North Cascades Ecosystem of northcentral Washington with about 5–10 grizzlies. These five ecosystems combine for a total of a maximum 1,729 wild grizzlies still persisting in the contiguous United States. Unfortunately, these populations are isolated from each other, inhibiting any genetic flow between ecosystems and creating low genetic diversity in remaining populations which can have negative long-time effects. This isolation poses one of the greatest threats to the future survival of the grizzly bear in the contiguous United States. Although there is no record of their existence in the United States east of the Rocky Mountain and Great Plain regions in human history, fossil records from Kentucky and the Ungava Peninsula do show in fact show that grizzly bears once roamed in eastern North America.
Although many people hold the belief some brown bears may be present in Mexico they are almost certainly extinct. The last Mexican grizzly bear was shot in 1976. None had been seen since 1960 prior.
In Europe, there are 14,000 brown bears in ten fragmented populations. They are extinct in the British Isles, extremely threatened in France and Spain, and in trouble over most of Central Europe.
Brown bears reach their western limits in Spain. In the Cantabrian mountains of northwest Spain, some 210 bears dwell in Asturias, Cantabria, Galicia and León, in the Picos de Europa and adjacent areas in 2013. As of 2015, the population was estimated at around 250 individuals, but only due it being a more extensive survey and their numbers may be declining rather than increasing. However, the population of brown bears in the Pyrenees mountains, in a range shared between France, Spain and Andorra,is much lower, estimated at 14 to 25, with a shortage of breeding females. Their rarity in this area has led biologists to release bears, mostly female, from Slovenia in spring 2006 to reduce the imbalance and preserve the species' presence in the area. The bears were released despite protests from French farmers.
A small population of brown bears (formerly assigned to the race Ursus arctos marsicanus which is now considered part of the nominate race) still lives in central Italy (Apennine Mountains, Abruzzo and Latium), with no more than 70 individuals, protected by strong laws, but endangered by the human presence in the area.
In eastern and northern Europe, the range of brown bear currently extends more broadly. Among the most populous countries for brown bears in the eastern region are Romania which has approximately 4,000–5,000 brown bears, Bulgaria with 900–1,200, Slovakia at about 600–800 bears, Slovenia at approximately 500–700 animals and Greece holds about 200 animals in the south. The Carpathian brown bear population of Romania is the largest in Europe outside of Russia. Despite the relatively large size of the country’s bear population, the species’ numbers there are declining alarmingly due to overhunting. There is also a smaller brown bear population in the Carpathian Mountains in Ukraine (estimated at about 200 in 2005), Slovakia and Poland (estimated at about 100 in 2009 in the latter country). The total Carpathian population is estimated at about 8,000.
Northern Europe is home to a large bear population, with an estimated 2,500 (range 2,350–2,900) in Sweden, about 1,600 in Finland, about 700 in Estonia and 70 in Norway, totaling to nearly 5,000 individuals in the wild. 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 northeast Italy, Slovenia, Croatia, Bosnia and Herzegovina, Serbia, Montenegro, Macedonia, Albania, Bulgaria and Greece. Brown bears inhabited the mountains of Austria until as recently as 2011, after a reintroduction effort failed and the species became extinct again. There is currently no effort to reintroduce the species into Austria.
Asia Minor and Middle East
In this part of the world, the brown bear occurs from Georgia, Armenia and Azerbaijan southbound spottily through Turkey, northernmost Iraq, western and northern Iran, thence discontinuously in northeastern Kazakhstan, southeastern Uzbekistan and north to Kyrgyzstan. The populations in these countries are generally very small and fragmented, thus at high risk of genetic isolation, and they occupy only small segments of their former range here. At least 20-30 were present in northern Iran as of 2015.
In Asia, brown bears are found in nearly every part of Russia, thence to the southeast in a small area of Northeast China, western China, and parts of North Korea. Further west, they reach the southern limits of their worldwide distribution, dwelling spottily in northern Pakistan, Afghanistan and the northernmost point of India, i.e. Jammu and Kashmir. They possibly persist in northern Nepal, northern Bhutan and northern Myanmar but are not confirmed residents today in these nations.
Three distinct lineages of the Hokkaido brown bear (Ursus arctos yesoensis L.) can also be found on the Japanese island of Hokkaidō. Hokkaido has the largest number of non-Russian brown bears in eastern Asia with about 2,000–3,000 animals, although, in 2015, the Biodiversity Division of the Hokkaido government estimated the population as being as high as 10,600.
Many people hold the belief some brown bears may be present in the Atlas Mountains of Morocco but there have been none sighted in the last century. In addition to the native Atlas bear the Romans apparently imported bears from Spain for spectacles with some escaping and founding a population in Africa, though it is doubtful that they still persist today.
This species inhabits the broadest range of habitats of any living bear species. They seem to have no altitudinal preferences and have been recorded from sea-level to an elevation of 5,000 m (16,000 ft) (the latter in the Himalayas). In most of their range, brown bears generally seems to prefer semiopen country, with a scattering of vegetation that can allow them a resting spot during the day. However, they have been recorded as inhabiting every variety of northern temperate forest known to occur. North American brown bears, or grizzly bears, generally seem to prefer open or semi-open landscapes, with the species once having been common on the Great Plains and continues to occur in sizeable numbers in tundra and coastal estuaries and islands. Variable numbers still occur in prairie areas of the northern Rocky Mountains (mostly in Canada but some in the contiguous United States). Where continuous and protected, such as the Greater Yellowstone Ecosystem, the prairie is near ideal interior habitat for the species.
In western Eurasia, they inhabit mostly mountainous woodlands, in ranges such as the Alps, the Pyrenees and the Caucasus, though they may have been driven into more wooded, precipitous habitats due to the prior extensive persecution of the species in some regions. Desolate parts of northern and eastern Europe, like large patches of Scandinavia and the Carpathian Mountains, have always been quite heavily forested and have maintained relatively stable populations of bears, indicating that the brown bears here are well-adapted to forest-dwelling, although they generally seek foraging opportunities in forest openings such as bogs. In general, enclosed forest is sub-standard foraging habitat for brown bears and so they occur irregularly in true taiga lands, despite the boreal forest falling at the middle of their circumpolar distribution.
In Central Asia, human disturbances are minimal as this area has a harsher environment and is more sparsely populated. In this part of the world, bears may be found in steppe, which is sparser and more desert-like than grassland habitats in North America that occur at similar latitudes, and some bears may live out their lives even in desert edge, such as those that live in the Middle East (Syrian bears) and the rare Gobi bear which is native only to the Chinese-Mongolian desert of its name and isolated from other populations. Alpine meadows are the typical habitat in the Himalayan and Tibetan populations of brown bear. In Siberia, the species seems well-adapted to living in almost all parts of the extensive pine forests, usually coming to waterways or poorly drained openings and bogs while feeding and sheltering in broad roots and trunks in the interior. Eastern Russian forests hold arguably the largest number of brown bears in the world outside of possibly Alaska and northwestern Canada. The brown bears of Hokkaido are also largely forest dwelling, but dwell in mixed forests dominated by broadleaf trees such as beech.
It is thought the Eurasian bears which colonized America were tundra-adapted (as are many grizzlies are today in North America) and the species is sometimes found around sub-Arctic ice fields. 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 North American cousins. Genetics relay that two separate radiations led to today’s North American brown bears one a coastal form that lead to Kodiak bear (from U. a. beringianus or a common ancestor) and one an interior form that lead to the grizzly bear (from U. a. lasiotus or a common ancestor). 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 (potentially another offshoot of a radiation of coastal brown bears). In non-Arctic areas, habitat loss is blamed as the leading cause of endangerment, followed by hunting.
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. 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 (Atlas bear), and Mexican subspecies, as well as brown bear populations in the Pacific Northwest were hunted to extinction in the nineteenth and twentieth centuries, and many of the southern Asian subspecies are highly endangered. The Syrian brown bear (Ursus arctos syriacus) is very rare and is has been extirpated from more than half of its historic range. One of the smallest-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 in central Italy is believed to have a population of just 30 to 40 bears.
The brown bear is extinct in: Algeria, Belgium, Denmark, Egypt; Germany; Hungary; Ireland, Israel; Jordan, Lebanon; Liechtenstein; Lithuania, Luxembourg, Mexico; Moldova; Monaco, Morocco; Netherlands; Portugal; San Marino; Switzerland; Syria, Tunisia, United Kingdom, Vatican. (Possibly extinct in Bhutan.)
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. Furthermore, yearling and newly independent bears are more likely to be active diurnally and many adult bears in low-disturbance areas are largely crepuscular. In summer through autumn, a brown bear can double its weight from the spring, gaining up to 180 kg (400 lb) of fat, on which it relies to make it through winter, when it becomes very lethargic. Although they are not full hibernators and can be woken easily, both sexes like to den in a protected spot during the winter months. Hibernation dens may consist of any spot that provides cover from the elements and that can accommodate their bodies, such as a cave, crevice, cavernous tree roots, or hollow logs.
Brown bears have one of the largest brain of any extant carnivoran relative to their body size and have been shown to engage in tool-use (e.g. using a barnacle-covered rock to scratch its neck), which requires advanced cognitive abilities. This species is mostly solitary, although bears may gather in large numbers at major food sources (e.g., moth colonies, open garbage dumps or rivers holding spawning salmon) and form social hierarchies based on age and size. Adult male bears are particularly aggressive and are avoided by adolescent and subadult males both at concentrated feeding opportunities and chance encounters. Female bears with cubs rival adult males in aggression, and are much more intolerant of other bears than single females. Young adolescent males tend to be least aggressive, and have been observed in nonantagonistic interactions with each other. Dominance between bears is asserted by making a frontal orientation, showing off canines, muzzle twisting and neck stretching to which a subordinate will respond with a lateral orientation, by turning away and dropping the head and by sitting or lying down. During combat, bears use their paws to strike their opponents in the chest or shoulders and bite the head or neck. In his Great Bear Almanac, Gary Brown lists 11 different sounds bears produce in 9 different contexts. Sounds expressing anger or aggravation include growls, roars, woofs, champs and smacks, while sounds expressing nervousness or pain include woofs, grunts, and bawls. Sows will bleat or hum when communicating with their cubs.
Brown bears usually occur over vast home ranges, however they are not highly territorial. Several adult bears often roam freely over the same vicinity without issue unless rights to a fertile female or food sources are being contested. Males always cover more area than females each year. Despite their lack of traditional territorial behavior, adult males can seem to have a “personal zone” in which other bears are not tolerated if they are seen. Males always wander further than females due to both increasing access to females and food sources while females are advantaged by smaller territories in part since it decreases the likelihood of encounters with male bears who may endanger their cubs. In areas where food is abundant and concentrated, such as coastal Alaska, home ranges for females are up to 24 km2 (9.3 sq mi) and for males are up to 89 km2 (34 sq mi). Similarly, in British Columbia, bears of the two sexes travel relatively compact home ranges of 115 km2 (44 sq mi) and 318 km2 (123 sq mi). In Yellowstone National Park, home ranges for females are up to 281 km2 (108 sq mi) and up to 874 km2 (337 sq mi) for males. In the central Arctic of Canada, where food sources are quite sparse, home ranges range up to 2,434 km2 (940 sq mi) in females and 8,171 km2 (3,155 sq mi) in males.
A study of male-inherited Y chromosome DNA sequence found that brown bears, over the past few 10,000 years, have shown strong male-biased dispersal That study found surprisingly similar Y chromosomes in brown bear populations as far apart as Norway and coastal Alaska, indicating extensive gene flow across Eurasia and North America. Notably, this contrasts with genetic signals from female-inherited mitochondrial DNA (mtDNA), where brown bears of different geographic regions typically show strong differences in their mtDNA, a result of female philopatry.
The mating season is from mid-May to early July, shifting later the further north the bears are found. Being serially monogamous, brown bears remain with the same mate from a couple of days to a couple of weeks. Outside of this narrow time frame, adult male and female brown bears show no sexual interest in each other. Females mature sexually between the age of 4 and 8 years of age, with an average age at sexual maturity of 5.2-5.5 years old, while males first mate about a year later on average, when they are large and strong enough to successfully compete with other males for mating rights. Males will try to mate with as many females as they can, usually a successful one mates with two females in a span of one to three weeks. The adult female brown bear is similarly promiscuous, mating with up to four, rarely even eight, males while in heat and potentially breeding with two males in a single day. Females come into oestrus on average every three to four years, with a full range of 2.4 to 5.7 years. The urine markings of a female in oestrus can attract several males via scent. Paternity DNA tests have shown that up to 29% of cubs in a litter will be from two to three different males. Dominant males may try to sequester a female for her entire oestrus period of approximately two weeks but usually are unable to retain her for the entire time. Copulation is vigorous and prolonged and can last up to an hour, although the mean time is about 23–24 minutes.
Males take no part in raising their cubs – parenting is left entirely to the females. Through the process of delayed implantation, a female's fertilized egg divides and floats freely 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. There have been cases of bears with as many as six cubs, although the average litter size is 1-3, with more than four being considered uncommon . There are records of females sometimes adopting stray cubs or even trading or kidnapping cubs when they emerge from hibernation (a larger female may claim cubs away from a smaller one). Older and larger females within a population 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 may weigh from 350 to 510 g (0.77 to 1.12 lb), again reportedly based on the age and condition of the mother. They feed on their mother's milk until spring or even early summer, depending on climate conditions. At this time, the cubs weigh 7 to 9 kg (15 to 20 lb) and have developed enough to follow her over long distances and begin to forage for solid food.
The cubs are fully dependent on the mother and a close bond is formed. During the dependency stage, the cubs learning (rather than instinctively inset from birth) survival techniques, such as which foods have the highest nutritional value and where to obtain them; how to hunt, fish, and defend themselves; and where to den. Increased brain size in large carnivores has been positively linked to whether a given species is solitary, as is the brown bear, or raises their offspring communally, thus female brown bears have relatively large, well-developed brains presumably key in teaching behavior. The cubs learn by following and imitating their mother's actions during the period they are with her. Cubs remain with their mother for an average of 2.5 years in North America, uncommonly being independent as early as 1.5 years of age or as late as 4.5 years of age. The stage at which independence is attained may generally be earlier in some parts of Eurasia, as the latest date which mother cubs were together was 2.3 years and most families separated in under two years in a study from Hokkaido and in Sweden most cubs on their own were still yearlings. Brown bears practice infanticide, as an adult male bear may kill the cubs of another bear. When adult male brown bears kill a cub it is usually because he is bringing the female into oestrus, as she will enter that state within 2–4 days after the death of her cubs. Cubs flee up a tree, if available, when they see a strange male bear, and the mother often successfully defends them, even though the male may be twice as heavy as she, although females have been known to lose their lives in these confrontations.
Longevity and mortality
The brown bear is naturally a long-living animal. Wild females have been known to be able to reproduce at as old as 28 years of age, the oldest known age for reproduction in the wild of any ursid. One average the peak reproductive age for females ranges from 4 to 20 years of age. On average, the lifespan of brown bears of both sexes from minimally hunted populations is estimated to be 25 years. The oldest wild brown bear on record was nearly 37 years old. The oldest recorded female in captivity was nearly 40 years old, while males in captivity have been verified to live up to 47 years, with another one possibility attaining 50 years of age. Ironically considering males potentially live longer in captivity, per a study at Yellowstone, female grizzly bears in the wild have a great annual survival rate than males did. Annual mortality for bears of any age is estimated at around 10% in most protected areas. However, in hunted populations, an estimated average mortality rate of 38% is given. Around 13% to 44% of cubs die within their first year even in well-protected areas. Cases of 75-100% of the young of the year dying are not uncommon. Beyond predation by other large predators (rarely by wolf packs or Siberian tigers (Panthera tigris altaica)) and brown bears, starvation and accidents claim a few cubs. Studies have indicated that the most prevalent source of mortality for first-year cubs is malnutrition. By the second to third years of their live, annual mortality in cubs in the care of their mother drops to 10-15%. Even in populations living in protected areas without legal, non-governmental hunting, though, humans are still the leading cause of mortality for brown bears. The largest number of legally hunting on the species occurs in Canada, Finland, Russia, Slovakia and Alaska. In many areas, hunting is unregulated and even where it legally permitted, most biologist feel that the numbers hunted are excessive considering this species low reproductive rates and sparse distribution. In different parts of the range, several brown bears may also be killed by automobile collisions, which is mostly a cause of mortality in the United States and Europe.
The brown bear is one of the most omnivorous animals in the world and has been recorded consuming the greatest variety of foods of any bear. Throughout life, this species is regularly curious about the potential of eating virtually any organism or object that they encounter. Certainly no other animal in their given ecosystems, short perhaps of other bear species and humans, can claim to feed on as broad a range of dietary opportunities. Food that is both abundant and easily obtained is preferred. Their jaw structure has evolved to fit their dietary habits. Their diet varies enormously throughout their differing areas based on opportunity. In spring, winter-provided carrion, grasses, shoots, sedges and forbs are the dietary mainstays for brown bears from almost every part of their distribution. Fruits, including berries, become increasingly important during summer and early autumn. Roots and bulbs become critical in autumn for some inland bear populations if fruit crops are poor. The dietary variability is illustrated in the western United States, as meat made up 51% of the average year-around diet for grizzly bears from Yellowstone National Park while it made up only 11% of the year-around diet for grizzlies from Glacier National Park a few hundred miles to the north.
Plants and fungi
Despite their reputation, most brown bears are not highly carnivorous, as they derive up to 90% of their dietary food energy from vegetable matter. Brown bears often feed on a variety of plant life, including berries, grasses, flowers, acorns (Quercus ssp.) and pine cones as well as mosses and fungi such as mushrooms. In total, over 200 plant species have been identified in their foods. Arguably the most herbivorous diets have come from the warmer temperate parts of Eurasia as more than 90% of the diet may be herbivorous. These include countries and regions such as Spain, Slovakia, most of the Balkans including Greece, Turkey, the Himalayas, and presumably the Middle East. In many inland portions of North America, the diet of grizzly bears is between 80 and 90% plant-based but animal meat can be much more important in some areas. It has been found that being restricted to a largely vegetarian diet puts constraints on the growth and size of bears who live off of them, largely because their digestive systems do not process plants as well as animal fats and proteins.
Among all living bears, brown bears are uniquely equipped to dig for tough foods such as roots and shoots. They use their long, strong claws to dig out earth to reach the roots and their powerful jaws to bite through them. For the most part, the consumed plant life in spring, predominantly roots immediately post-hibernation and grasses later in spring, is not highly nutritious for bears and mainly staves off hunger and starvation until more nutritious food is available. Brown bears have difficulty digesting large quantities of tough, fibrous foods. Hedysarum roots are among the most commonly eaten foods from throughout the range and can become important substitutes if stable foods such as fruits become unavailable. Corms and bulbs are important when available as they are one of the greater sources of protein in plant life as are hard masts such as acorns. Brown bears are restricted in their access to hard masts compared to black bears because of the limited climbing abilities of grown bears and therefore are confined largely to masts fallen to the ground, pirated from other creatures or within a reach of about 3 m (9 ft 10 in) that the bears can stretch to with their paws extended and standing on their hindlegs. Hard masts can become the most important food (although consumed mainly in late summer and fall) where available in large quantities such as on Hokkaido, Italy and Spain. One of the most important foods in the Rocky Mountain region of the United States is the Whitebark pine nut (Pinus albicaulis), which is attained perhaps a majority of the time by raiding the once abundant caches of American red squirrels (Tamiasciurus hudsonicus) rather than direct foraging. The decline of whitebark pine nut due to the inadvertent introduction by man of the invasive, virulent fungi Cronartium ribicola has in turn required grizzlies to seek alternate food sources, many of which are carnivorous. In a Greek food study, soft mast were found to outrank hard masts as a food source, with about a quarter of the year-around diet comprised by the legume Medicago.
Fruits and berries are indispensable for brown bears in most areas as a high-energy food stuff for bears which is necessary to survive the hibernation cycle. The variety of fruits consumed is high, with most of the well-known, wild fruiting plants in temperate North America and Eurasia attracting brown bears in late summer and fall. Among the most prominent fruits found in their foods from through the range include many Prunus species including prunes and cherries, crowberries (Empetrum nigrum), pears (Pyrus ssp.), crabapples (Malus ssp.), brambles (Rubus fruticosus), raspberries (Rubus idaeus), bearberries (Arctostaphylos ssp.) (reportedly named for bears’ fondness for them), blueberries (Vaccinium ssp.), lingonberries (Vaccinium vitis-idaea) and huckleberries (Vaccinium parvifolium). Fruit appears to become more secondary in the diet in areas where hard masts and animal protein are abundant in late summer and fall, as these more protein-rich foods appear to be more nutritious for bears than carbohydrate-rich fruits are, despite their fondness for fruit. Even where fruit are commonly eaten, other foods must be eaten to meet nutritional requirements. It is estimated that a small female brown bear may need to eat nearly 30,000 berries each day in late summer/fall in order to subsist on a purely fruit-based diet.
Brown bears will also commonly consume animal matter, which in summer and autumn may regularly be in the form of insects, larvae and grubs, including beehives. Most insects eaten as the highly social varieties found in colonial nests which provides a likely greater quantity of food, although they will also tear apart rotten logs on the forest floor, turn over rocks or simply dig in soft earth in attempts to consume individual invertebrates such as bugs, beetles and earthworms. Honey bees and wasps are important supplemental foods in Eurasia from the furthest west of their range, in Spain, to the furthest east, in Hokkaido. Bears in Yellowstone and Montana eat an enormous number of moths during the summer, sometimes consuming as many as 40,000 army cutworm moths (Euxoa auxiliaris) in a single day, and may derive up to half of their annual food energy from these insects. In Europe, a variety of species of ants have been found to factor heavily into the diet in some areas such as Scandinavia and eastern Europe. In Slovenia, for example, up to 25% of the dry mass consumed by bears was comprised by ants. Locally heavy consumption of ants has been reported in North America as well, as in west-central Alberta, 49% of scat contained ants. This species mainly feed on ants with a passive response to the colony being dug out and low levels of formic acid, therefore carpenter ants (Camponotus ssp.), which are accessed through rotten logs rather than underground colonies, are preferred where available. Other important insect aggregations that brown bears feed heavily on in some regions include ladybirds and caddisfly. Brown bears living near coastal regions will regularly eat crabs and clams. In Alaska’s Katmai National Park and Preserve, bears along the beaches of estuaries regularly dig through the sand for soft-shell clam (Mya arenaria) and Pacific razor clam (Siliqua patula), providing a more nutritious source of dietary energy in spring than plant life before fish become available there. The zarigani (Cambaroides japonicus), a type of crayfish, of Hokkaido is also an important, protein-rich dietary supplement for bears there.
By far the closest dietary relationship between brown bears and fish occurs between the salmon and trout of the Oncorhynchus genus, particularly in coastal areas but also in some inland areas of North America. 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. Sockeye salmon (O. nerka) and pink salmon (O. gorbuscha) are the two most commonly predated, but many coho (O. kisutch), Chinook (O. tshawytscha), masu (O. masou) and chum salmon (O. keta) are also taken. Even in the coastal ranges of the Pacific, a diverse omnivorous diet is eaten, with the salmon spawning reliably providing food only in late summer and early fall. Exceptionally, salmon may come to inland rivers as early as June in the Brooks River when other coastal Alaskan bears are in their dietary “lean period” and provide food for bears sooner than normal. On Kodiak island, it appears the availability of alternate food sources is high, as berry crops are often profuse, marine organisms often wash up and ungulates both wild and domesticated are available. The fishing techniques of bears are well-documented. They often congregate around falls when the salmon are forced to breach the water, at which point the bears will try to catch the fish in mid-air (often with their mouths). They will also wade into shallow waters, hoping to pin a slippery salmon with their claws. While they may eat almost all the parts of the fish, bears at the peak of spawning, when there is usually a glut of fish to feed on, may eat only the most nutritious parts of the salmon (including the eggs and head) and then indifferently leave the rest of the carcass to scavengers, which can include red foxes (Vulpes vulpes), bald eagles (Haliaeetus leucocephalus), common ravens (Corvus corax) and gulls. Despite their normally solitary habits, Brown bears will gather rather closely in numbers at good spawning sites. The largest and most powerful males claim the most fruitful fishing spots and bears (especially males) will sometimes fight over the rights to a prime fishing spot. Despite their aggressive defensive abilities, female brown bears usually select sub-optimal fishing spots to avoid male bears that could potential threaten their cubs.
One other key relationship occurs between brown bears and Oncorhynchus species occurs with the grizzly bear and the cutthroat trout (O. clarki) in the Rockies such as around Yellowstone. Here this species was consumed in considerable numbers although, like the whitebark pine nut, this food source has declined due to invasive species introduced by man, i.e. invasive trout which are outcompeting cutthroat trout. The now extinct California grizzly bear was also a fairly specialized Onocorhynchus predator in California's mountain streams and rivers, principally of rainbow trout (O. mykiss). Outside of Pacific-based salmonids, predatory relationships between brown bears and fish are uncommon. Predation on broad whitefish (Coregonus nasus) and longnose suckers (Catostomus catostomus) has been reported in sub-Arctic Canada and northern pike (Esox lucius) and grayling (Thymallus thymallus) in Siberia, plus other older records of brown bears hunting miscellaneous freshwater fish in Eurasia.
Beyond the regular predation of salmon, most brown bears are not particularly active predators. Nonetheless, brown bears are capable of obtaining practically all forms of the mammals that they encounter: from mouse-like rodents to those as fearsome as a tiger or as large as a bison. Over 100 species of mammal have been recorded either in the scats of brown bears or have been observed as being killed or consumed by the species, although much of this consumption probably represents merely scavenging on carrion.
A perhaps surprisingly high balance of mammalian foods are comprised by rodents or similar smallish mammals, as about half of the species consumed by brown bears are those weighing less than 10 kg (22 lb) on average. These may include hares (Lepus ssp.), pikas (Ochotona ssp.) marmots (Marmota ssp.), ground squirrels, chipmunks, mice, rats, lemmings and voles. Due to their propensity for digging, brown bears are able to smell out active subterranean burrows of these small mammals and either wait quietly or furiously dig away until the animals are either displaced and lunged at or are cornered in their burrows. Not only do they consume the small mammals but they also feed on their caches, as has been recorded in grizzly bears attacking voles and northern pocket gophers (Thomomys talpoides). In some areas, caches may be the primary target when bears dig at these animals burrows, this may be the case with Siberian chipmunks (Eutamias sibiricus), whose hoards can contain up to 20 kg (44 lb) of food, with the chipmunks themselves only being caught occasionally. With particular regularity, tundra-dwelling grizzlies will wait at burrows of Arctic ground squirrels (Spermophilus parryii) hoping to pick off a few of the 1 kg (2.2 lb) rodents. Ground squirrel hunting is most successful in September and October, when early snow may impede the rodents’ rocky escape routes. In Denali National Park, Arctic ground squirrels represent about 8% of the year-around diet of grizzly bears and are the most consistent source of animal protein for grizzlies there. An even more important dietary relationship with a small mammal occurs in the Tibetan blue bear, which is apparently the most completely carnivorous brown bear race, foraging most regularly for plateau pikas (Ochotona curzoniae), a species about one-sixth the weight of an Arctic ground squirrel. As many as 25 pikas have been found in a single bear’s stomach and in Changtang 60% of the diet consisted of pikas. Where plateau pikas are absent, as in the Mustang region of Nepal, Himalayan marmots (Marmota himalayana) became the dietary stable of the bear, occurring in about half of nearly a thousand scats. Large rodents such as beavers (Castor spp.) and North American porcupines (Erethizon dorsatum) are rare prey items, mostly due to differing habitat preferences, as well as the obvious defenses of the latter. Up to five species of cetacean have been recorded as a food source in the coastal regions of Alaska, the Central Arctic and (formerly) California when beached.
In most of their range, brown bears regularly feed on ungulates. In many cases, this important food source is obtained as carrion. Carrion is mostly eaten in spring, when winter snow and ice conditions (including snow-slides) and starvation claim many ungulate lives. As carcasses are often solidly frozen when encounter, brown bears may sit on them to thaw them sufficiently for consumption. While perhaps a majority of bears of the species will charge at ungulates at one point in their lives, many predation attempts start with the bear clumsily and half-heartedly pursuing the prey and end with the prey escaping alive. On the other hand, some brown bears are quite self-assured predators who habitually pursue and catch large prey items mainly comprised by ungulates. Such bears are usually taught how to hunt by their mothers from an early age. They are the most regular predator of ungulates among extant bear species. The extent of hunting behavior differs by region. For example, in Slovenia, ungulate meat was four times more likely to be obtained as carrion than through hunting, while on the contrary in east-central Alaska, live hunting of ungulates was four times more likely than scavenging of carrion. The extent of carnivory in brown bears has been proven to increase at northern latitudes. When brown bears attack these large animals, they usually target young or infirm ones, as they are easier to catch. Typically when hunting (especially with young prey), the bear pins its prey to the ground and then immediately tears and eats it alive. Despite being characterized as unskilled predator with minimally refined hunting skills, most individual bears who are routine ungulate-predators have shown the ability to vary their hunting strategy and have hunting success rates comparable to other large, solitary carnivorans. Brown bears will on occasion bite or swipe some prey in order to stun it enough to knock it over for consumption. To pick out young or infirm individuals, bears will charge at herds so the slower-moving and more vulnerable individuals will be made apparent. Brown bears may also ambush young animals by finding them via scent. Despite being characterized as a danger to ungulates mostly on spring neonatal young in the first couple days of life when they have undeveloped legs and cannot run at full speed, young ungulates may be pursued well into summer or fall after they’ve developed running abilities. Most attacks on adult ungulate occur when the prey has some variety of physical disadvantage. When emerging from hibernation, brown bears, whose broad paws allow them to walk over most ice and snow, may pursue large prey such as moose whose hooves cannot support them on encrusted snow. Similarly, predatory attacks on large prey sometimes occur at riverbeds, when it is more difficult for the prey specimen to run away due to muddy or slippery soil. On rare occasions, most importantly for confronting unusually large, fully-grown and dangerous prey, bears kill them by hitting with their powerful forearms, which can break the necks and backs of large creatures such as adult moose and adult bison.
The leading ungulate prey for brown bears is normally deer. Up to a dozen species have been eaten by brown bears but the main prey species are the larger species they encounter: elk (Cervus canadensis), moose (Alces alces) and caribou (Rangifer tarandus). Larger deer are preferred because they tend to be less agile and swift than small or medium-sized deer (although a caribou can handily outpace a grizzly bear in the open), they are found in large quantities in several areas inhabited by brown bears and provide a larger meal per carcass. Moose may be preferred where found in large numbers because of their solitary habits and tendency to dwell in wooded areas, both of which makes them easier to ambush. Despite its diminished reputation as a predator, the brown bear is the most dangerous solitary predator of moose, only packs of wolves are a more regular predator and even Siberian tigers take other prey primarily (elk and boar) where they co-exist with the giant deer. Brown bear normally avoid the potential risks of hunting large deer, which can potentially fight back but usually escape bears by running, by picking out young calves or sickly adults from deer herds. In northeastern Norway, it was found that moose were the most important single food item (present in up to 45% of scats and locally comprising more than 70% of the bear's dietary energy) for local brown bears and several local bears appear to be specialized moose hunters, most often picking off sickly yearling moose and pregnant but healthy cows. In a study from Yellowstone National Park, grizzly bears who derived much of the food energy from ungulates were studied, 30% of the ungulates consumed were through predation, the remaining amount from scavenging of carcasses, elk, bison and moose (the 3 largest native ungulates in the region) each nearly comprised a quarter each of the overall ungulate diet. 13% of the total ungulates actively hunted and killed per that study in Yellowstone were elk calves, while 8% of the actively and successfully hunted prey there were adult cow elk. Despite their lack of preference for smaller deer, other species including red deer (Cervus elaphus), sika deer (Cervus nippon ), axis deer (Axis axis), European roe deer (Capreolus capreolus), Siberian roe deer (Capreolus pygargus), fallow deer (Dama dama), mule deer (Odocoileus hemionus) and white-tailed deer (Odocoileus virginianus) have turned up in their diet.
As many as 20 species of bovids are also potential prey including various sheep, goats, antelope, bison (Bison ssp.) and muskoxen (Ovibos moschatus). Bovids are mostly taken in random encounters when bears come across a vulnerable, usually young or sickly individuals, as smaller species are extremely agile (and often live in rocky environments) and larger varieties are potentially dangerous especially if aware of the bear’s presence. In some parts of eastern Europe and Russia, wild boar (Sus scrofa) may be taken in surprisingly large quantities considering the mostly herbivorous reputation of bears in these regions. One study from the Amur territory of Russia found that brown bears were actually more prolific killers of wild boars than both tigers and gray wolves, but probably are biased by scarcity of tigers in the region after overhunting of the big cat. In rare cases, brown bears are capable of killing bulls of the largest ungulates in regions they inhabit, reportedly including moose, muskox, yak (Bos grunniens) and both American and European bison (Bison bison & bonasus). Remarkably, such attacks are sometimes carried out by bears that were not particularly large including interior sow grizzlies or small-bodied bears from the Central Arctic and some ungulates taken may exceptionally be up to two to three times the weight of the attacking bear. However, most of the bears who took adult moose in east-central Alaska and Scandinavia were large, mature males.
This species may eat birds and their eggs, including almost entirely ground- or rock-nesting species. Although not typically able to capture a healthy grown bird, eggs, nestlings and fledglings of large bird species can be very attractive to brown bears. Species attacked have ranged can be any size available from Aleutian terns (Onychoprion aleuticus) to trumpeter and whooper swans (Cygnus buccinator & cygnus). Most recorded avian prey have consisted of geese and sea ducks nesting in the lower Arctic Circle, followed by coveys of galliforms, as these birds place their nests in shallow water and on the ground as well as raise their chicks in such areas, so are relatively more vulnerable. Large birds of prey including sea eagles, gyrfalcons (Falco rusticolus) and golden eagles (Aquila chrysaetos) are sometimes exploited as prey if nesting in rock formations are accessible on foot and eagles and falcons may furiously dive at bears near their nests. Due to their inhabitance of cooler temperate areas, reptiles and amphibians are rarely a food source and have been verified as prey only in a few cases: frogs in the Italian Alps, rat snakes in Hokkaido, grass lizards in the Amur territory and tortoises in Greece.
When forced to live in close proximity with humans and their domesticated animals, bears may potentially predate any type of domestic animal. Most type of livestock have been domesticated for millennia and have little to no anti-predator defenses. Therefore, brown bears are somewhat more likely to attack healthy adults than they are of healthy adult wild animals. Among domestic and farm animals, domestic cattle (Bos primigenius taurus) are sometimes exploited as prey. Cattle are bitten on the neck, back or head and then the abdominal cavity is opened for eating. In Norway, free-ranging domestic sheep (Ovis aries) are numerous and the local brown bears derive 65–87% of their dietary energy in late summer from sheep. Due to the aforementioned vulnerability, examination of Norwegian sheep remains suggest many of the sheep consumed there are adults that were killed by the bears rather than merely scavenged, and thus some local farmers received partial compensation for their stock losses. In nearby northern Sweden, free-ranging sheep are not present and the bear derive their food predominantly from natural sources. Horses (Equus ferus caballus), goats (Capra aegagrus hircus), pigs (Sus scrofa domesticus), chickens (Gallus gallus domesticus) and dogs (Canis lupus familaris) may be opportunistically killed in several parts of the brown bear’s range as well. Plants and fruit farmed by humans are readily consumed as well, including corn (Zea mays ), wheat (Triticum spp.), apple (Malus domestica), sorghum (Sorghum ssp.), melons and any form of berries. They will also feed at domestic bee farms, readily consuming both honey and the contents of the honey bee (Apis mellifera) colony. Human foods and trash or refuse is eaten when possible. When an open garbage dump was kept in Yellowstone, brown bears were one of the most voracious and regular scavengers. The dump was closed after both brown and American black bears came to associate humans with food and lost their natural fear of them. In other areas, such as Alaska, dumps may continue to be an attractant for brown bears.
Enemies and competitors
While feeding on carrion, brown bears use their size to intimidate other predators, such as wolves, cougars (Puma concolor), tigers (Panthera tigris), and black bears from their kills. Due to the formidable size and aggressive disposition, predation by wild animals outside of their own species is rare for brown bears of any age, even cubs are often safe due to their watchful mother. There are two records of golden eagles (Aquila chrysaetos) predating brown bear cubs.
Adult bears are generally immune to predatory attacks except from tigers and other bears. Siberian tigers (Panthera tigris altaica) prefer preying on young bears but smaller, fully grown adult female brown bears outside their dens may also be taken. Successful predatory attacks by tigers on adult brown bears are usually on female bears, with or without cubs, in their dens. Of 44 recorded encounters between the two predators, 20 resulted in confrontations; in 50% of these, the brown bears were killed, in 27% the tigers were killed, and 23% of the cases ended with both animals surviving and parting ways despite injuries sustained in the conflict. Some bears emerging from hibernation seek out tigers in order to steal their kills. Despite the possibility of tiger predation, some large brown bears may actually benefit from the tiger's presence by appropriating tiger kills that the bears may not be able to successfully hunt themselves and follow tiger tracks. Geptner et al. (1972) stated bears are generally afraid of tigers and change their path after coming across tiger trails. In the winters of 1970–1973, Yudakov and Nikolaev recorded 1 case of brown bear showing no fear of the tigers and another case of brown bear changing path upon crossing tiger tracks. Other researchers have observed bears following tiger tracks for various reasons. Bears frequently track down tigers to usurp their kills, with occasional fatal outcomes for the tiger. A report from 1973 describes twelve known cases of brown bears killing tigers, including adult males; in all cases the tigers were subsequently eaten by the bears. There are reports of brown bears specifically targeting Amur tigers and leopards to abstract their prey. In the Sikhote-Alin reserve, 35% of tiger kills were stolen by bears, with tigers either departing entirely or leaving part of the kill for the bear.
Brown bears regularly intimidate gray wolves (Canis lupus) away from their kills, with wolves occurring in most of the brown bear’s worldwide distribution. In Yellowstone National Park, brown bears pirate wolf kills so often, Yellowstone's Wolf Project director Doug Smith wrote, "It's not a matter of if the bears will come calling after a kill, but when." Similarly, in Denali National Park, grizzly bears routinely rob wolf packs of their kills. On the contrary, in Katmai National Park and Preserve, wolves, even lone wolves, may manage to displace brown bears at carrion sites. Despite the high animosity between the two species, most confrontations at kill sites or large carcasses end without bloodshed on either side. Though conflict over carcasses is common, on rare occasions the two predators tolerate each other on the same kill. To date, there are only a few cases of fully-grown wolves being killed by brown bears and none of wolves killing healthy adult brown bears. Given the opportunity, however, both species will prey on the other's cubs. Conclusively, the individual power of the bear against the collective strength of the wolf pack usually results in a long battle for kills or domination.
In some areas, the grizzly bear also regularly displaces cougars (Puma concolor) from their kills with some estimates showing cougar locally lose up to a third of their dietary energy to grizzly bears. Cougars kill small bear cubs on rare occasions, but there was one report of a bear killing a cougar of unknown age and condition between 1993 and 1996. Eurasian lynx (Lynx lynx), the largest type of lynx and the only to regularly take large prey, is similarly an habitual victim of kleptoparasitism to brown bears throughout Eurasia. Brown bears also co-exist with leopards (Panthera pardus) (in very small remnant wild parts of the Middle East, Jammu and Kashmir, northeastern China and Primorsky Krai) and snow leopards (Panthera uncia), in several areas of northern central Asia and the Tibetan Plateau). Although the brown bears’ interactions with these big cats are little known, they probably have similar relationships as grizzly bears do with cougars in North America. Snow leopards and Tibetan blue bears are verified, however, to be a threat to one another’s cubs.
Smaller carnivorous animals are dominated by brown bears and generally avoid direct interactions with them, unless attempting to steal scraps of food. Species which utilize underground or rock dens tend to be more vulnerable to predatory attacks by brown bears, several mustelids including badgers are not infrequently preyed upon, and seemingly even arboreal martens may be attacked (especially if unhealthy or caught in furbearer traps). In North America, both species of otter have been known to be ambushed by brown bears when on land. On the contrary, wolverines (Gulo gulo)for one have been persistent enough to fend off a grizzly bear as much as ten times their weight off a kill. In some rare cases, wolverines have lost their lives to grizzly bears and wolverines in Denali National Park will reportedly try to avoid encounters with grizzlies. Beyond wolves, other canids may occasionally be killed around their den (most likely pups or kits) or adults if overly incautious near a carrion site including coyotes (Canis latrans), multiple species of fox and raccoon dogs (Nyctereutes procyonoides). Medium-sized cats may also be rarely killed by brown bears. Seals are on rare occasions killed by brown bears, including eye-witness accounts of Russian bears ambushing spotted (Phoca largha) and harbor seals (Phoca vitulina). Consumption of ringed (Pusa hispida ) and bearded seal (Erignathus barbatus) has reported in the Mackenzie river delta, presumably via predation or scavenging of polar bear kills, as pinnipeds are not usually encountered as carrion from land.
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 to brown bears in open, unforested 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. Confrontation is mostly avoided due to the black bear's diurnal habits and preference for heavily forested areas, as opposed to the brown bear's largely nocturnal habits and preference for open spaces. Where they do not live in close proximity to grizzly bears and especially where found near human habitations, American black bears may become to a larger extent nocturnal. Brown bears may also kill Asian black bears, though the latter species probably largely avoids conflicts with the brown bear due to similar habits and habitat preferences to the American black species. Brown bears will eat the fruit dropped by the Asian black bear from trees, as they themselves are too large and cumbersome to climb. Improbably, in the Himalayas, brown bears are reportedly intimidated by Asian black bears in confrontations. However, the Himalayan black bears are reportedly more aggressive towards humans than the region’s Himalayan brown bear and the latter is one of the smaller races of brown bear, it is still somewhat larger than the black bear. In Siberia, the opposite is true and the black bears are not known to attack people but brown bears are. Both black bears seem to be most vulnerable to predatory attacks by brown bears when the latter species leaves hibernation sooner in early spring and ambushes the smaller ursids in their dens.
There has been a recent increase in interactions between brown bears and polar bears, theorized to be caused by climate change. Brown bears have been seen moving increasingly northward into territories formerly claimed by polar bears. Despite averaging somewhat smaller, brown bears tend to dominate polar bears in disputes over carcasses, and dead polar bear cubs have been found in brown bear dens.
Large herbivores, such as moose, buffalo, and muskox may have an intolerance of brown bears due to their possible threat to vulnerable members of their herds or themselves; moose regularly charge grizzly bears in their calf's defense, but seldom are the bears killed. Bison have been known to fatally injure lone grizzly bears in battles, and even a mountain goat (Oreamnos americanus) was observed to do so with its horns, although herbivores are rarely a serious danger to brown bears.
Paleo-ecology and interactions
In the roughly 0.9 million years of its existence, brown bears have had to contend with multiple competing species, a majority of which went extinct at the end of the Pleistocene era. In its much longer history in Eurasia, brown bears diverged from the two species of cave bear, the giant (U. spelaeus) and small cave bears (U. rossicus), two species that it existed alongside in what is now Europe for the larger form and Central Asia and Siberia for the smaller cave bear. The cave bears were similar in size to the larger forms of brown bears and polar bear alive today in terms of length but were bulkier, with much higher density skeletal remains, and presumably rather heavier than the modern brown bear, with the giant cave bear about the same length as a modern Kodiak bear but projected to be some 30% heavier. Pleistocene era brown bears appeared to have been somewhat larger and more carnivorous than most modern forms based on skull dimensions. The cave bears usually have been deemed highly herbivorous, to a greater extent than the brown bear, based on examinations of stable isotopes and dental morphology. Recent studies, however, have shown that cave bears could have opportunistically adapt to a fairly omnivorous diet and consumed many herbivore carcasses. Despite this, the dietary differences and differing habitat preferences (caves of course being much more habitually used in the cave species than the brown bear) allowed the three Ursus to persist at the same time in different parts of Eurasia.
A more dangerous competitor was encountered by brown bears upon crossing the Bering Land Bridge about 100,000 years ago in the form of the short-faced bear, a long-legged bear that was estimated to have weighed about twice as much on average as a modern Kodiak bear. Although at one time deemed a hyper-carnivorous predator that used its long legs to run down large prey, more recent studies have indicated that like the modern brown bear, an omnivorous opportunist that probably scavenged many meals and presumably used its size and great height to intimidate large predators at kills. Until it declined along with its food sources until dwindling to extinction, the short-faced bear presumably prevented the brown bear from spreading south, mainly through competition but also to some extent predation. A single fossil ulna some 70,000 years old found in Great Britain, deemed to come from an extremely large subadult Pleistocene polar bear (Ursus maritimus tyrannus), was projected to be the largest known form of the Ursus genus. However, this cannot be ruled out as an extinct population of brown bear based on the inconclusiveness of the only known fossil. Other carnivorans during the Pleistocene that were possibly occasional predators based on their large sizes of early brown bears (at least females and cubs) were largely big cats including the cave lion (Panthera leo spelaea) and the saber-toothed Machairodus in Eurasia and, perhaps rarely in southern Beringia, the American lion (Panthera leo atrox) and the saber-toothed Smilodon and Homotherium in North America. Interactions with these large cats were probably not highly disparate from those that continue today in brown bears with the Siberian tiger. Unlike most of these forms, the brown bear was able to survive the Quaternary extinction event that concluded the ice age. Presumably this was due to its greater dietary and habitat plasticity and may have adopted a more extensively herbivorous diet as most temperate-zone herbivores that may have provided meals for more specialized large land carnivores went extinct as a warming climate killed off their food source.
It is likely that humans caused extinction of bear populations and fragmentation of their habitats since prehistorical time. It is, for instance, shown that bear populations from the Greater Caucasus and the Lesser Caucasus Mountains, separated by the densely populated Transcaucasian Depression, have been matrilineally isolated since the early Holocene era, i.e., after permanent human settlements appeared throughout the area While hunting by early humans was a (previously underestimated) factor in many of the Quartenary extinction events, a perhaps stronger factor in this species survival compared to many other northern Pleistocene bears is brown bears’ stronger genetic diversity. In comparison, the giant cave bear appeared to enter a genetic bottleneck that started a population decline some 25,000 years before the species’ extinction.
Relationship with humans
Conflicts between bears and humans
Brown bears usually avoid areas where extensive development or urbanization has occurred, unlike the smaller, more inoffensive American black bear which can adapt to peri-urban regions. Under many circumstances, extensive human development may cause brown bears to alter their home ranges. However, bears can easily lose their natural cautiousness upon being attracted to human-created food sources, such as garbage dumps, litter bins, and dumpsters. Brown bears may even venture into human dwellings or barns in search of food as humans encroach into bear habitats. In different parts of their distribution, brown bears sometimes kill and eat domesticated animals. 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.
When bears come to associate human activity with a "food reward", they are likely to continue to become emboldened; the likelihood of human-bear encounters increases, as they may return to the same location despite relocation. Relocation of the bear has been used to separate the bear from the human environment, but it does not address the problem of the bear's newly learned association of humans with food or 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, a reserve located in the western United States, contains prime habitat for the grizzly bear (Ursus arctos horribilis), and 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. As a result, 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 bears 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 as sheep and goat are relatively easy for a bear to kill. In some cases, the shepherds shoot the bear, thinking their livelihood is under threat. Many are now better informed about the ample compensation available, and will make a claim when they lose livestock to a bear. Another issue in several parts of their range in Europe is supplemental feeding stations where various kind of animal carrion is offered, which are set up mainly in Scandinavia and eastern Europe both to support the locally threatened species and so humans can enjoy watching bears that may otherwise prove evasive. Despite that most stations were cautiously set in remote areas far from human habitations, some brown bears in such areas have become conditioned to associate humans with food and become excessively bold “problem bears”. Also supplemental feeding appears to cause no decrease in livestock predation.
Relationship with Native Americans
Native American tribes sympatric with brown bears often view them with a mixture of awe and fear. North American brown bears have at times been so feared by the natives, that they were rarely hunted, especially alone. At traditional grizzly hunts in some western tribes such as the Gwich’in the expedition was conducted with the same preparation and ceremoniality as intertribal warfare, and was never done except with a company of 4–10 warriors. The tribe members who dealt the killing blow were highly esteemed among their compatriots. Californian natives actively avoided prime bear habitat, and would not allow their young men to hunt alone, for fear of bear attacks. During the Spanish colonial period, some tribes, instead of hunting grizzlies themselves, would seek aid from European colonists to deal with problem bears. Many authors in the American west wrote of natives or voyageurs with lacerated faces and missing noses or eyes due to attacks from grizzlies.
Many Native American tribes both respect and fear the brown bear. In Kwakiutl mythology, black and brown bears became enemies when Grizzly Bear Woman killed Black Bear Woman for being lazy. Black Bear Woman's children, in turn, killed Grizzly Bear Woman's own cubs. Sleeping Bear Dunes is named after a Native American legend, where a female bear and her cub swam across Lake Michigan. Exhausted from their journey, the bears rested on the shoreline and fell sound asleep. Over the years, the sand covered them up, creating a huge sand dune.
There are an average of two fatal attacks by bears per year in North America. In Scandinavia, there are only four known cases since 1902 of bear encounters which have resulted in death. The two most common causes for bear attack are surprise and curiosity. Some types of bears, such as polar bears, are more likely to attack humans when searching for food, while American black bears are much less likely to attack. Despite their boldness and potential for predation if the bear is hungry, polar bears rarely attack humans because they are infrequently encountered in the Arctic sea.
The Alaska Science Center ranks the following as the most likely reasons for bear attacks:
- Invaded personal space (this includes a mother bear protecting her young)
- Predatory intent
- Hunting wounded
- Carcass defense
- Provoked charge
Aggressive behavior in brown bears is favored by numerous selection variables. Unlike the smaller black bears, adult brown bears are too large and have improperly shaped claws to escape danger by climbing trees, so they respond to danger by standing their ground and warding off their attackers. Increased aggressiveness also assists female brown bears in better ensuring the survival of their young to reproductive age. Mothers defending cubs are the most prone to attacking, being responsible for 70% of brown bear-caused human fatalities in North America.
Attacks on humans
Brown bears seldom attack humans on sight, and usually avoid people. In Russia, it estimated that one in a thousand on-foot encounters with brown bears results in attack. They are, however, unpredictable in temperament, and may attack if they are surprised or feel threatened. Despite the low rate of attack, they appear to be the most dangerous northern carnivoran to humans, attacking more people on average annually than American black bears or northern races of Asian black bear and Siberian tigers, cougars or gray wolves. Several large carnivorans from tropical regions of Africa and Asia may be more dangerous to humans than brown bears, including other ursids such as the sloth bear and Indian races of the Asian black bear. Each of the latter species of bear may kill up to a dozen people annually in certain Indian districts, about as many in a relatively small area as all of the world’s brown bears combined. The high levels of human-directed aggression in these ursine bears is reportedly their evolution with once large numbers of predatory Bengal tigers (arguably itself the world’s most dangerous carnivoran to humans even with its extreme decline in modern times, being statistically much more likely to attack than their northern Siberian cousins) and a very large human population, increasing the risk of surprising and angering a defensive black or sloth bear, the latter species often charging aggressively rather than fleeing if a surprise encounter occurs as do most other bear species.
Sows with cubs account for the majority of injuries and fatalities by brown bears in North America. Habituated or food-conditioned bears can also be dangerous, as their long-term exposure to humans causes them to lose their natural shyness, and, in some cases, to associate humans with food. Small parties of one or two people are more often attacked by brown bears than large groups, with only one known case of an attack on a group of six or more. In that instance, it is thought that due to surprise, the grizzly bear may not have recognized the size of the group. In the majority of attacks resulting in injury, brown bears precede the attack with a growl or huffing sound. In contrast to injuries caused by American black bears, which are usually minor, brown bear attacks more often tend to result in serious injury and, in some cases, death. Brown bears seem to confront humans as they would when fighting other bears: they rise up on their hind legs, and attempt to "disarm" their victims by biting and holding on to the lower jaw to avoid being bitten in turn. Due to the bears' enormous physical strength, even a single bite or swipe can be deadly, as in tigers, with some human victims having had their heads completely crushed by a bear bite. Most attacks occur in the months of July, August, and September, the time when the number of outdoor recreationalists, such as hikers or hunters, is higher. People who assert their presence through noises tend to be less vulnerable, as they alert bears to their presence. In direct confrontations, people who run are statistically more likely to be attacked than those who stand their ground. Violent encounters with brown bears usually last only a few minutes, though they can be prolonged if the victims fight back. In Alberta, two common behaviors by human hunters, imitating the calls of deer to attract them and carrying ungulate carcasses, seem to court aggressive behavior and lead to a higher rate of attack from grizzly bears.
Attacks on humans are considered extremely rare in the former Soviet Union, though exceptions exist in districts where they are not as often pursued by hunters. Siberian bears, for example, tend to be much bolder toward humans than their shyer, more persecuted European counterparts. The delineation in Eurasia between areas where aggressiveness of bears tends to increase is the Ural Mountains, although the bears of eastern Europe are somewhat more aggressive than those of western Europe. In 2008, a platinum mining compound in the Olyotorsky district of northern Kamchatka was besieged by a group of 30 bears, who killed two guards and prevented workers from leaving their homes. Ten people a year on average are killed by brown bears in Russia, more than all the other parts of brown bear’s international range combined, although Russia also holds more brown bears than all other parts of the world combined. In Scandinavia, only three fatal attacks were recorded in the 20th century.
In Japan, a large brown bear nicknamed "Kesagake" (袈裟懸け, "kesa-style slasher") made history for causing the worst bear attack in Japanese history at Tomamae, Hokkaidō during numerous encounters during December 1915. It killed seven people and wounded three others (with possibly another three previous fatalities to its credit) before being gunned down after a large-scale beast-hunt. Today, there is still a shrine at Rokusensawa (六線沢), where the event took place, in memory of the victims of the incident.
Within Yellowstone National Park, injuries caused by grizzly attacks in developed areas averaged approximately one per year during the 1930s through to the 1950s, though it increased to four per year during the 1960s. They then decreased to one injury every two years during the 1970s. Between 1980 and 2002, there have been only two human injuries caused by grizzly bears in a developed area. Though grizzly attacks were rare in the backcountry before 1970, the number of attacks increased to an average of approximately one per year during the 1970s, 1980s, and 1990s. In Alberta, from 1960 to 1998, the number of attacks by grizzly bears ending in injury were nearly three times more common than attacks ending in injury by American black bears despite the black bear being an estimated 38 times more numerous in the province than grizzlies.
History of defense from bears
A study by US and Canadian researchers has found pepper spray to be more effective at stopping aggressive bear behavior than guns, working in 92% of studied incidents versus 67% for guns. Carrying pepper spray is highly recommended by many authorities when traveling in bear country; however, carrying two means of deterrent, one of which is a large caliber gun, is also advised. Solid shotgun slugs, or three buckshot rounds, or a pistol of .44 caliber or more is suggested if a heavy hunting rifle is not available. Guns remain a viable, last resort option to be used in defense of life from aggressive bears. Too often, people do not carry a proper caliber weapon to neutralize the bear. According to the Alaska Science Center, a 12 gauge shotgun with slugs has been the most effective weapon. There have been fewer injuries as a result of only carrying lethal loads in the shotgun, as opposed to deterrent rounds. State of Alaska Defense of Life or Property (DLP) laws require one to report the kill to authorities, and salvage the hide, skull, and claws. A page at the State of Alaska Department of Natural Resources website offers information about how to "select a gun that will stop a bear (12-gauge shotgun or .300 mag rifle)."
Campers are often told to wear bright colored red ribbons and bells, and carry whistles to ward off bears. They are told to look for grizzly scat in camping areas, and be careful to carry the bells and whistles in those areas. Grizzly scat is difficult to differentiate from black bear scat, as diet is in a constant state of flux depending on the availability of seasonal food items. 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. Moving camps immediately is another recommended method.
Brown bears often figure into the literature of Europe and North America, in particular that which is written for children. "The Brown Bear of Norway" is a Scottish fairy tale telling the adventures of a girl who married a prince magically turned into a bear, and who managed to get him back into a human form by the force of her love and after many trials and difficulties. With "Goldilocks and the Three Bears", a story from England, the three bears are usually depicted as brown bears. In German speaking countries, children are often told the fairytale of Snow White and Rose Red; the handsome prince in this tale has been transfigured into a brown bear. In the United States, parents often read their preschool age children the book Brown Bear, Brown Bear, What Do You See? to teach them their colors and how they are associated with different animals.
The Russian bear is a common national personification for Russia (as well as the former Soviet Union) despite the country having no appointed national animal. The brown bear is Finland's national animal.
The grizzly bear is the state animal of Montana. The California golden bear is the state animal of California. Both animals are sub-species of the brown bear, and the species was extirpated from the latter state.
The coat of arms of Madrid depicts a bear reaching up into a madroño or strawberry tree (Arbutus unedo) to eat some of its fruit, whereas the Swiss city of Bern's coat of arms also depicts a bear and the city's name is popularly thought to derive from the German word for bear. The brown bear is depicted on the reverse of the Croatian 5 kuna coin, minted since 1993.
The Bundesliga club Bayern Munich has a brown bear mascot named Berni. The National Football League (NFL) franchise in Chicago, Illinois, is named the Bears. In this context, no differentiation between black and brown bears is needed. The school mascot for George Fox University, Brown University, the University of California, Los Angeles, the University of California, Berkeley, the University of California, Riverside, and the University of Alberta is the brown bear.
In the town of Prats de Molló, in Vallespir, southern France, a "bear festival" (festa de l'ós) is celebrated annually at the beginning of spring, in which the locals dress up as bears, cover themselves with soot or coal and oil, and "attack" the onlookers, attempting to get everyone dirty. The festival ends with the ball de l'os (bear dance).
- The grizzly bear, sometimes called the silvertip bear, is listed as threatened in the contiguous United States. It is slowly repopulating in areas where it was previously extirpated, though it is still vulnerable.
- The California golden bear (Ursus arctos californicus) disappeared from the state of California in 1922, when the last one was shot in Tulare County. It is the official state animal.
- The Mexican grizzly bear is listed as an endangered species, but it may be extinct.
- In Canada, it is listed as vulnerable in Alberta, British Columbia, Northwest Territories, and Yukon Territory. Prairie populations of grizzly bear are listed as extirpated in Alberta, Manitoba, and Saskatchewan.
- The brown bear is a European Protected Species, given protection throughout the European Union.
Potential Maximum Size
The maximum size of Kodiak or brown bears in general is not certain. It is known that males, if they retain access to a consistent source of protein and have a genetic inclination for large size, can exceed expected size parameters if they live well past a decade. However, as with many very large animals, many reported outsized wild brown bears are based on dated hunting reports with often only the skins, which can be stretched several feet beyond their natural dimensions in life, taken from the field. These bears, taken by hunters without scientific staff on hand to verify, leave open the possibility of dubious claims, mistakes and exaggerations, and tend to be reported in modern writings with only fragmentary details. In some cases, the skulls, a more consistent, reliable method of estimating overall size, are occasionally taken however. Exceptionally huge male Kodiaks can stand over 3 m (9 ft 10 in) tall while on their hind legs and may exceed 1.6 m (5 ft 3 in) high at the shoulder. The weight of these enormous bruins is less certain. The following is a list of the largest brown bears reported in literature, with the threshold that all these animals were either estimated or scaled to exceed 700 kg (1,500 lb), therefore being past expected sizes.
- A grizzly bear shot in Nevada in 1881 was reportedly almost exactly 700 kg (1,500 lb).
- A bear shot on Kodiak Island was estimated to weigh around 726 kg (1,601 lb) in life as it weighed 545 kg (1,202 lb) after it had been field-dressing (entrails and blood removed).
- The heaviest verified and well-documented wild Kodiak bear weighed about 751 kg (1,656 lb), as per the Gerard Wood's 1983 publication for the Guinness Book of World Records but, according to some sources, it was reportedly scaled after field-dressing (entrails and blood removed) and so was estimated in life to weigh “a little over a ton”. The stretched skin of this specimen was 4.1 m (13 ft 5 in) indicating that in life this specimen probably measured over 3.1 m (10 ft 2 in) in head-and-body length.
- Whitaker (1996), of the National Audubon Society, and Nowak (1999) accepted cases of male Kodiaks weighing 770 and 780 kg (1,700 and 1,720 lb), respectively.
- An outsized Kodiak Island shot in 1949 was estimated to have weighed some 817 kg (1,801 lb).
- The same weight of 817 kg (1,801 lb) was reported for a coastal brown bear killed on the Kenai Peninsula in 1917.
- The skin of a specimen shot in Cold Bay, Alaska was submitted to and logged by Robert L. Rausch of the Museum of Southwestern Biology in 1952; it reportedly scaled 885 kg (1,951 lb) and measured 3.32 m (10 ft 11 in) in total head-to-tail, unstretched length.
- One California grizzly reportedly weighed 1,000 kg (2,200 lb).
- A bear weighing 1,000 kg (2,200 lb) was also claimed for a coastal Alaskan bear without further details, by Corbet (1966). Furthermore, the Smithsonian Institution accepted the same weight. It is not clear if this references a bear that was shot in 1954 in Port Heiden, Alaska and taken to Alaska Department of Fish and Game in King Salmon, Alaska where the above weight was estimated (but not scaled) for an enormous specimen by the department.
- Gary Brown, in his 1996 publication "The Great Bear Almanac", claimed that the heaviest recorded brown bear weighed over 1,150 kg (2,540 lb), without going into further detail beyond mentioning it was of the Kamchatka brown bear subspecies rather than the Kodiak.
- David W. MacDonald, a well-respected biologist claimed in his guide to the "Mammals of Europe" (2002) while reviewing the species that it is not unusual for old Kodiak bear males to weigh up to 680 kg (1,500 lb) during autumn hypophagia and some specimens can attain 780 kg (1,720 lb) or more in mass. MacDonald also mentions in this account that the Kodiak can attain a maximum mass of 1,500 kg (3,300 lb) although he again does not specify verifiable details.
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