Brown Bear
The brown bear is a large bear distributed across much of northern Eurasia and North America and is the largest land-based predator on earth. There are several recognized subspecies within the brown bear species.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, and Mexican subspecies were hunted to extinction in the nineteenth and twentieth centuries, and many of the southern Asian subspecies are highly endangered. The brown bear's principal range includes parts of Russia, India, China, Canada, the United States, Scandinavia and the Carpathian region. The brown bear is recognized as a national and state animal in several European countries. It is the most widely distributed of all bears.
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Description
Brown bears are often not brown. 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 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 and sometimes 7 to 10 centimetres 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 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 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. 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.
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 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 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. 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 size of brown bears is the most variable of modern bears. The typical size depends upon which population it is from. A large barren ground brown bear might seem quite small elsewhere.The brown bear (grizzly bear in 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 and the Gobi Desert 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 have been weighed up to 680 kg (1,500 lb), 481 kg (1,060 lb) and 600 kg (1,300 lb), respectively.
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, likely the ancestor of the modern-day American grizzly, which can obtain sizes comparable to those of the coastal bears.
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, likely the ancestor of the modern-day American grizzly, which can obtain sizes comparable to those of the coastal bears.
Habitat
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,[55] the United States with 32,500, and Canada with around 25,000. In Europe, there are 14,000 brown bears in ten fragmented populations, from Spain.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 over hunting. There is also a smaller brown bear population in the Carpathian Mountains in Ukraine.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. 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 semi open 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.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. 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.
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 over hunting. There is also a smaller brown bear population in the Carpathian Mountains in Ukraine.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. 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 semi open 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.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. 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.
Reproduction
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.[81] 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.[82] Brown bears practice infanticide.[83] 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.
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.[82] Brown bears practice infanticide.[83] 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.