Temporal range: Late Pleistocene – Recent
|Brown bear (U. arctos) in Hallo Bay, Katmai National Park, Alaska|
16, see text
|Brown bear range map|
The brown bear (Ursus arctos) is a large bear distributed across much of northern Eurasia and North America. Adult bears generally weigh between 100 and 635 kg (220 and 1,400 lb). Its largest subspecies, the Kodiak bear, rivals the polar bear as the largest member of the bear family and as the largest land-based predator. There are several recognized subspecies within the brown bear species. 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. An adult grizzly living inland in Yukon may weigh as little as 80 kg (180 lb), while an adult coastal brown bear in nearby coastal Alaska living on a steady, nutritious diet of spawning salmon may weigh as much as 680 kg (1,500 lb). The exact number of overall brown subspecies remains in debate.
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 twentieth centuries, and many of the southern Asian subspecies are highly endangered. The smallest 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's principal range includes parts of Russia, India, China, Canada, the United States (mostly Alaska), Scandinavia and the Carpathian region (especially Romania), The brown bear is recognized as a national and state animal in several European countries. It is the most widely distributed of all bears.
Naming and etymologyEdit
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). During the Old West, the grizzly was termed "Old Ephraim" and sometimes as "Moccasin Joe". The scientific name of the brown bear, Ursus arctos, comes from the Latin "ursus", meaning "bear", and Άρκτος "arctos", from the Greek word for bear.
Taxonomy and evolutionEdit
Brown bears are thought to have evolved from Ursus etruscus. The oldest fossils occur in China from about 0.5 million years ago. They 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 outcompeted cave bears. The species entered Alaska 100,000 years ago, though they did not move south until 13,000 years ago. It is thought 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: 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.
There is little agreement on classification of brown bears. Some systems have proposed as many as 90 subspecies, while recent DNA analysis has identified as few as five clades. DNA analysis recently revealed that the identified subspecies of brown bears, both Eurasian and North American, are genetically quite homogeneous, and that their genetic phylogeography does not correspond to their traditional taxonomy. As of 2005, 16 living subspecies have been recognized. The subspecies have been listed as follows:
|Ursus arctos arctos – Eurasian brown bear||Europe, Caucasus, Siberia (except the east) and Mongolia||A predominantly dark colored (rarely light colored), moderately sized subspecies with dark claws, the Eurasian browns occurring in Siberia are larger than their European counterparts, as they are hunted less. Where found in Europe, primarily a forest creature|
|Ursus arctos beringianus – Kamchatka brown bear (or Far Eastern brown bear)||Kamchatka Peninsula and Paramushir Island||This is a very large, dark colored form. Light colored forms are encountered less than in European-Siberian subspecies. The claws are dark; it is thought to be the ancestor of the Kodiak bear U. a. middendorffi. and Peninsular brown bears U. a. gyas of Alaska.|
|Ursus arctos collaris – East Siberian brown bear||East Siberia from the Yenisei River to the Altai Mountains, also found in northern Mongolia||A predominantly dark form, it is intermediate in size between U. a. arctos and U. a. beringianus, with a proportionately larger skull.|
|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||Nepal, Pakistan, and Northern India||Has a reddish-brown or sandy coat color and 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 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: Heilongjiang, Japan: Hokkaidō||This bear is thought to be the ancestor of U. a. horribilis.|
|Ursus arctos marsicanus – Marsican 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 pruinosus – Tibetan blue bear||Tibetan plateau  an isolated sub-population lives in the Gobi Desert.||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 forms a "collar". The skull is distinguished its relatively flattened choanae, an arch-like curve of the molar row and large teeth.|
|Ursus arctos syriacus – Syrian brown bear||The trans-Caucasus, Syria, Iraq, Turkey (Asia Minor), Iran, Afghanistan, Pakistan, western Himalayas and the Pamir-Alai and Tien Shan mountains, probable historical presence in Israel||The Syrian is a light colored, moderate to small-sized subspecies with light claws. Recently, however, it was shown that this form, at least matrilineally, is not monophyletic and belongs to Ursus arctos arctos.|
|Ursus arctos alascensis – Alaska brown bear||Coastal Alaska|
|Ursus arctos californicus – †California grizzly (extinct)||California||The last known bear was shot in California in 1922.|
|Ursus arctos dalli - Dall Island brown bear||Dall Island|
|Ursus arctos gyas – Peninsular brown bear||Alaska Peninsula||Considered by some biologists to be same subspecies as U. a. middendorffi.|
|Ursus arctos horribilis – Grizzly bear||Northern and Western Canada, Alaska, and the northwestern United States, historically existed in Great Plains||Grizzlies are identified by a medium to dark brown coat with gray or blond "grizzled" tips on the fur. Smaller than coastal bears, a large male grizzly can weigh up to 364 kilograms (802 lb) in inland areas, with bears in the Yukon region weighing as little as 80 kg (180 lb). Coastal bears may be nearly twice a mountain grizzly's weight. Highly adaptable: it can live in montane pine forests, temperate rainforest, semi-arid scrubland, and shortgrass prairie.|
|Ursus arctos middendorffi – Kodiak bear||Kodiak, Afognak, Shuyak Islands (Alaska)||This is the largest subspecies of brown bear, with other coastal brown bears potentially reaching nearly as large.|
|Ursus arctos nelsoni – †Mexican grizzly bear (extinct)||Formerly northern Mexico, including Chihuahua, Coahuila, and Sonora, southwestern United States including southern ranges of Texas, Arizona, and New Mexico||This bear is believed extinct due to cattle ranching in both the United States and Mexico. Distinct in its ability to survive arid conditions, it could live in both montane pine forests of Mexico and canyonlands of 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, this species is called "clade I" by Waits, and others, and is part of the subspecies identified as U. a. sitkensis, by Hall and as U. a. dalli by Kurtén.|
|Ursus arctos stikeenensis||Northwestern British Columbia Around the Stikine River.||Considered by some biologists to be same subspecies as U. a. horribilis.|
|Ursus arctos ugavaesis – †Ungava brown bear (extinct)||Ungava Peninsula, Quebec||Inhabited the forests of northern Quebec. The species was hunted by Indians and early settlers, and the last one was killed in c. 1913.|
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 subspeciesEdit
|Ursus arctos pyrenaicus – Iberian brown bear, sometimes called Cantabrian brown bear, now considered Ursus arctos arctos – European 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 European brown bear can be divided into two distinct lineages. "There is a clear division into two main mitochondrial lineages in modern European 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 animal on the Iberian Peninsula, although one of the smallest of the brown bears, weigh between 130 and 180 kg (290 and 400 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.
Brown bears have long, thick fur, with a moderately long mane at the back of the neck. 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. Black hairs usually have white tips. 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.
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 sometimes 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. 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 climb trees as can both species of black bear. 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, with huge Kodiak bears having measured up to 46 cm (18 in) along their rear foot.
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: 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. Although they have powerful jaws, brown bear jaws are incapable of breaking large bones with the ease of spotted hyenas.
The brown bear is the most variably sized of extant bear species. The dimensions of brown bears fluctuate very greatly according to sex, age, individual, geographic location, and season. The normal range of physical dimensions for a brown bear is a head-and-body length of 1.4 to 2.8 m (4.6 to 9.2 ft) and a shoulder height of 70 to 153 cm (28 to 60 in). Males are invariably larger than females, typically weighing around 30% more in most races. The tail is relatively short, ranging from 6 to 22 cm (2.4 to 8.7 in) in length.
Young of the year typically weigh 2–27 kg (4.4–59.5 lb), while yearlings typically weigh 9–37 kg (20–82 lb).
Generally speaking, brown bears weigh the least when they emerge from hibernation in the spring and then reach peak weights when preparing for hibernation in the fall (when they often gorge on large food stuffs). Some subspecies show considerable variation. Whereas Eurasian brown bear (U. a. arctos) and grizzly bears (U. a. horribilis) from Northern Europe, Yellowstone National Park or interior Alaska seasonally weigh on average between 115 and 360 kg (254 and 794 lb), bears from the Yukon Delta, interior British Columbia, Jasper National Park and southern Europe can weigh from 55 to 155 kg (121 to 342 lb) on average. Bears from the Syrian (U. a. syriacus) and the Gobi Desert (U. a. gobiensis) subspecies are around the same mass as the smaller Eurasian brown and grizzly bears and can exceptionally measure as small as 1 m (3.3 ft) in head-and-body length. On the other end of the scale among interior brown bears, exceptional grizzly, Eurasian brown bears, and East Siberian brown bears (U. a. collaris) have been weighed up to 680 kg (1,500 lb), 481 kg (1,060 lb) and 600 kg (1,300 lb), respectively. 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. Interior brown bears are generally smaller than is often perceived, being around the same weight as an average African lion at an estimate average of 180 kg (400 lb) in males and 135 kg (298 lb) in females. The largest inland brown bear subspecies appears to be the Ussuri brown bear (U. a. lasiotus), likely the ancestor of the modern-day American grizzly, which can obtain sizes comparable to those of the coastal bears as described below.
The brown bears found in coastal regions of Alaska and far eastern Russia are the largest. The largest subspecies is the Kodiak bear (U. a. middendorffi), followed closely by the Kamchatka brown bear (U. a. beringianus), although bears from other coastal regions of eastern Asia and western North America can be comparably large. In these areas, the female averages from 181.4 to 318 kg (400 to 701 lb) and the male averages from 272 to 635 kg (600 to 1,400 lb). The heaviest verified Kodiak bear weighed about 748 kg (1,650 lb). It is not unusual for Kodiak bear males to weigh up to 680 kg (1,500 lb) in fall with some specimens attaining 780 kg (1,720 lb) or more.[verification needed] Such huge males can stand over 3 m (9.8 ft) tall while on their hind legs and loom 1.5 m (5 ft) high at the shoulder. The heaviest recorded brown bear weighed over 1,150 kilograms (2,500 lb).[verification needed] Furthermore, a maximum weight of 1,500 kg (3,300 lb) for the Kodiak bear was published.[verification needed]
Distribution and habitatEdit
Brown bears were once native to much of Asia, the Atlas Mountains of Africa, 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. About 95% of the brown bear population in the United States is in Alaska, though in the lower 48 states, they are repopulating slowly but steadily along the Rockies and the western Great Plains. Although many people hold the belief some brown bears may be present in Mexico and the Atlas Mountains of Morocco, both are almost certainly extinct. The last Mexican grizzly bear was shot in 1960. In Europe, there are 14,000 brown bears in ten fragmented populations, from Spain (estimated at only 20–25 animals in the Pyrenees in 2010, in a range shared between France, Spain and Andorra, and some 210 animals in Asturias, Cantabria, Galicia and León, in the Picos de Europa and adjacent areas in 2013  in the west, to Russia in the east, and from Sweden and Finland in the north to Romania (4000–5000), Bulgaria (900–1200), Slovakia (with about 600–800 animals), Slovenia (500–700 animals) and Greece (with about 200 animals) in the south. They are extinct in the British Isles, extremely threatened in France and Spain, and in trouble over most of Central Europe. The Carpathian brown bear population of Romania is the largest in Europe outside Russia, estimated at 4,500 to 5,000 bears, although 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. 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 live in Alaska, east through the Yukon and Northwest Territories, south through British Columbia and through the western half of Alberta. The Alaskan population is estimated at a healthy 32,000 individuals. Small populations exist in the Greater Yellowstone Ecosystem of northwest Wyoming (with about 600 animals), the Northern Continental Divide Ecosystem of northwest Montana (with about 750 animals), the Cabinet-Yaak Ecosystem of northwest Montana and northeast Idaho (with about 30–40 animals), the Selkirk Ecosystem of northeast Washington and northwest Idaho (with about 40–50 animals), and the North Cascades Ecosystem of northcentral Washington (with about 5–10 animals). These five ecosystems combine for a total of roughly 1,470 wild grizzlies still persisting in the contiguous United States. Unfortunately, these populations are isolated from each other, inhibiting any genetic flow between ecosystems. This poses one of the greatest threats to the future survival of the grizzly bear in the contiguous United States.
In Asia, brown bears are found primarily throughout Russia, thence more spottily southwest to parts of the Middle East, to as far south as southwestern Iran, and to the southeast in a small area of Northeast China, Western China, and parts of North Korea, Pakistan, Afghanistan and India. They can also be found on the Japanese island of Hokkaidō, which holds the largest number of non-Russian brown bears in eastern Asia with about 2,000–3,000 animals.
The population of brown bears in the Pyrenees mountain range between France and Spain is extremely low, estimated at 14 to 18, with a shortage of 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 (Ursus arctos marsicanus) 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 Arctic areas, the potential habitat of the brown bear is increasing. The warming of that region has allowed the species to move farther north into what was once exclusively the domain of the polar bear. In non-Arctic areas, habitat loss is blamed as the leading cause of endangerment, followed by hunting.
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). 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. 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, alpine meadows and even desert edge. In Siberia, the species seems well-adapted to living in denser pine forests. Eastern Russian forests hold arguably the largest number of brown bears in the world outside of possibly Alaska and northeastern Canada. It is thought the Eurasian bears which colonized America were tundra-adapted 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.
Although the brown bear is primarily nocturnal, it is frequently seen in morning and early evening hours. In summer through autumn, it can double its weight, 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, such as a cave, crevice, or hollow log, during the winter months. Brown bears are mostly solitary, although they 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. Female bears with cubs rival adult males in aggression, and are 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 and will try to mate with as many females as they can (although females are not monogamous either). 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. Being serially monogamous, brown bears remain with the same mate from several days to a couple of weeks. Females mature sexually between the age of 4 and 8 years of age, 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, however, 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. The average litter has one to four cubs, usually two. There have been cases of bears with as many as six cubs. There are records of females sometimes adopting stray cubs or even trading cubs when they emerge from hibernation. Older females tend to give birth to larger litters. The size of a litter also depends on factors such as geographic location and food supply. At birth, the cubs are blind, toothless, hairless, and weigh less than 450 grams (1 lb). 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 and begin to forage for solid food.
Cubs remain with their mother from two to four years (exceptionally to 4 and a half years), during which time they learn 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. The cubs learn by following and imitating their mother's actions during the period they are with her. Brown bears practice infanticide. An adult male bear may kill the cubs of another bear either to make the female sexually receptive or simply for consumption. Cubs flee up a tree when they see a strange male bear, and the mother often successfully defends them, even though the male may be twice as heavy as she.
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. Males commonly can live to 25 years, with the oldest female having been 37 years old. The species can live to 48 years of age in captivity. 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. Beyond predation by other large predators (rarely by gray wolf packs or Siberian tigers) and brown bears, starvation and accidents claim a few cubs. 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.
The Brown Bear is one of the most omnivorous animals in the world and has been recorded as 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. Food that is both abundant and easily accessed or caught is preferred. Their jaw structure has evolved to fit their dietary habits. Their diet varies enormously throughout their differing areas based on opportunity.
Despite their reputation, most brown bears are not highly carnivorous, as they derive up to 90% of their dietary food energy from vegetable matter. They often feed on a variety of plant life, including berries, grasses, flowers, acorns and pine cones as well as fungi such as mushrooms. Among all 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. In spring, winter-provided carrion, grasses, shoots, sedges and forbs are the dietary mainstays for brown bears internationally. 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. They will also commonly consume animal matter, which in summer and autumn may regularly be in the form of insects, larvae and grubs, including beehives. Bears in Yellowstone eat an enormous number of moths during the summer, sometimes as many as 40,000 army cutworm moths in a single day, and may derive up to half of their annual food energy from these insects. Brown bears living near coastal regions will regularly eat crabs and clams. In Alaska, bears along the beaches of estuaries regularly dig through the sand for clams. This species may eat birds and their eggs, including almost entirely ground- or rock-nesting species. The diet may be supplemented by rodents or similar smallish mammals, including marmots, ground squirrels, mice, rats, lemmings and voles. With particular regularity, bears in Denali National Park will wait at burrows of Arctic ground squirrels hoping to pick off a few of the 1 kg (2.2 lb) rodents.
In the Kamchatka peninsula and several parts of coastal Alaska, brown bears feed mostly on spawning salmon, whose nutrition and abundance explain the enormous size of the bears in these areas. 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 nutrious 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, bald eagles, common ravens 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.
Beyond the regular predation of salmon, most brown bears are not particularly active predators. While perhaps a majority of bears of the species will charge at large prey at one point in their lives and most eat carrion, 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. Such bears are usually taught how to hunt by their mothers from an early age. Large mammals preyed on can include various deer species such as elk, red deer, axis deer, European roe deer, Siberian roe deer, fallow deer, mule deer, white tailed deer, moose and caribou. Bovids are also regular prey including various sheep, goats, antelope, bison and muskoxen, as are wild boars. 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. It will also 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. 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, while confronting fully-grown, 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. They also feed on carrion, and use their size to intimidate other predators, such as wolves, cougars, tigers, and black bears from their kills. Carrion is especially important in the early spring (when the bears are emerging from hibernation), much of it comprised by winter-killed big game. Cannibalism is not unheard of, though predation is not normally believed to be the primary motivation when brown bears attack each other.
When forced to live in close proximity with humans and their domesticated animals, bears may potentially predate any type of domestic animal. Among these, domestic cattle are sometimes exploited as prey. Cattle are bitten on the neck, back or head and then the abdominal cavity is opened for eating. Plants and fruit farmed by humans are readily consumed as well, including corn, wheat, sorghum, 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 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.
Interspecific predatory relationshipsEdit
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Brown bears often use their large size for intimidation when a kill or a territory is in dispute with another large predator and they are normally dominant in such interactions. Sometimes, the conflict will escalate to the point of violence, but usually threat displays are sufficient, since most animals try to avoid potential bodily harm. However, the massive strength and size of the brown bear will usually result in its winning violent conflicts, even against wolf packs and Siberian tigers. In situations where the interspecies conflict turns deadly, brown bears may also eat the competitor, despite it not being the primary reason for attack.
Brown bears regularly intimidate wolves away from their kills. 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." 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 is a single case of fully-grown wolves being killed by a grizzly bear. 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 brown bear also regularly displaces cougars from their kills. Cougars kill small bear cubs on rare occasions, and there have been reports of bears killing fully-grown cougars. Other accounts, told primarily from the 19th and early 20th centuries, tell of cougars and bears engaging in prolonged combat and ending with both combatants fatally wounded. Brown bears are known to handle lions well when the two species interact in circuses. A Kodiak bear in the 1920s reportedly killed a man-eating African lion "so quickly the big audience hardly knew how it was done." An earlier account from the 1890s tells of a 700 lb grizzly bear and a 550 lb African lion engaging in a bloody, prolonged fight in a bullring and ending with the latter badly injured.
Smaller carnivorous animals, including coyotes, wolverines, lynxes and any other sympatric carnivores or raptorial birds, are dominated by Brown bears and generally avoid direct interactions with them, unless attempting to steal scraps of food. However, wolverines have been persistent enough to fend off a grizzly bear as much as ten times their weight off a kill. There is one record of a golden eagle predating a Brown bear cub.
Large herbivores, such as moose, buffalo, and muskox may have an intolerance of brown bears due to their possible threat to calves; moose regularly charge grizzly bears in their calf's defense. Bison have been known to fatally injure lone grizzly bears in battles, and even a mountain goat was observed to do so with its horns.
Adult bears are generally immune to predatory attacks except from other bears. Some bears emerging from hibernation seek out tigers in order to steal their kills. Indeed, Russian researchers have identified "satellite bears" who "follow tigers over extensive periods of time, sequentially usurping kills"; these bears were observed tracking tigers in spring snow and regularly usurped their kills. In the Russian Far East, brown bears along with smaller Asiatic black bears constitute 5–8% of the diet of Siberian tigers. In particular, the brown bear's input is estimated to be 1.0–1.5% in one source. However, another source states that such attacks are rare and do not have any actual significance because Siberian tigers are almost extinct. Siberian tigers most typically attack brown bears in the winter in the hibernaculum or in the late autumn and early spring, and when ungulate populations decrease. Tigers typically attack bears by surprise when hunting them and are believed to forgo attacks if the bear is aware of their presence. Adult bears, generally smaller ones, are sometimes vulnerable to tiger attacks and have been killed in their dens in winter, with the tiger taking advantage of the bear's hibernating condition. There are also records of bears killing tiger, either in self-defense, or in disputes over kills or for consumption.
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. 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. They 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.
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. Brown bears tend to dominate polar bears in disputes over carcasses, and dead polar bear cubs have been found in brown bear dens.
Relationship with humansEdit
Conflicts between bears and humansEdit
Bears become attracted to human-created food sources, such as garbage dumps, litter bins, and dumpsters; they venture into human dwellings or barns in search of food as humans encroach into bear habitats. In the U.S., bears sometimes kill and eat farm animals. 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. 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.
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. 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.
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
Relationship with Native AmericansEdit
Native American tribes sympatric with brown bears often viewed them with a mixture of awe and fear. North American brown bears were so feared by the natives, that they were rarely hunted, especially alone. When natives hunted grizzlies, 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 voyagers with lacerated faces and missing noses or eyes due to attacks from grizzlies.
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.
Many Native American tribes both respected and feared the brown bear, even thinking of it as a god. One tale tells of how the black bear was a creation of the Great Spirit, while the grizzly was created by the Evil Spirit. 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.
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.
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 humansEdit
Brown bears seldom attack humans on sight, and usually avoid people. They are, however, unpredictable in temperament, and may attack if they are surprised or feel threatened. Sows with cubs account for the majority of injuries and fatalities 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 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 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 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.
Attacks on humans are considered extremely rare in the former Soviet Union, though exceptions exist in districts where they are not pursued by hunters. Siberian bears, for example, tend to be much bolder toward humans than their shyer, more persecuted European counterparts. 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 are killed by brown bears in Russia. 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 (including one pregnant woman) 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.
History of defense from bearsEdit
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.
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.
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)." This information is helpful for people venturing into "bear country", regardless of state or country,
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 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.
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.
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.
- The brown bear is the national animal of Finland.
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