Bear
Bears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats throughout the Northern Hemisphere and partially in the Southern Hemisphere. Bears are found on the continents of North America, South America, Europe, and Asia.
Common characteristics of modern bears include large bodies with stocky legs, long snouts, shaggy hair, plantigrade paws with five nonretractile claws, and short tails. While the polar bear is mostly carnivorous, and the giant panda feeds almost entirely on bamboo, the remaining six species are omnivorous with varied diets.
With the exception of courting individuals and mothers with their young, bears are typically solitary animals. They are generally diurnal, but may be active during the night (nocturnal) or twilight (crepuscular), particularly around humans. Bears possess an excellent sense of smell and, despite their heavy build and awkward gait, are adept runners, climbers, and swimmers. Bears use shelters, such as caves and burrows, as their dens; most species occupy their dens during the winter for a long period (up to 100 days) of sleep similar to hibernation.
Bears have been hunted since prehistoric times for their meat and fur. With their tremendous physical presence and charisma, they play a prominent role in the arts, mythology, and other cultural aspects of various human societies. In modern times, the bears' existence has been pressured through the encroachment on their habitats and the illegal trade of bears and bear parts, including the Asian bile bear market. The IUCN lists six bear species as vulnerable or endangered, and even least concern species, such as the brown bear, are at risk of extirpation in certain countries. The poaching and international trade of these most threatened populations are prohibited, but still ongoing.
Morphology:
Bears are generally bulky and robust animals with relatively short legs. They are sexually dimorphic with regard to size, with the males being larger. Larger species tend to show increased levels of sexual dimorphism in comparison to smaller species and where a species varies in size across its distribution, individuals from larger-sized areas tend also to vary more. Bears include the most massive terrestrial members of the order Carnivora. Some exceptional polar bears and Kodiak bears (a brown bear subspecies) have been weighed at 1,002 kg (2,209 lb) and 751 kg (1,656 lb) respectively. As to which species is the largest depends on whether the assessment is based on which species has the largest individuals (brown bears) or on the largest average size (polar bears), as some races of brown bears are much smaller than polar bears. Adult male Kodiak bears average 480 to 533 kg (1,058 to 1,175 lb) compared to an average of 386 to 408 kg (851 to 899 lb) in adult male polar bears, per the Guinness Book of World Records. The smallest bears are the sun bears of Asia, which weigh an average of 65 kg (143 lb) for the males and 45 kg (99 lb) for the females, though the smallest mature females can weigh only 20 kg (44 lb). All "medium"-sized bear species (which include the other five extant species) are around the same average weight, with males averaging around 100 to 120 kg (220 to 260 lb) and females averaging around 60 to 85 kg (132 to 187 lb), although it is not uncommon for male American black bears to considerably exceed "average" weights. Head-and-body length can range from 120 cm (47 in) in sun bears to 300 cm (120 in) in large polar and brown bears and shoulder height can range from 60 cm (24 in) to over 160 cm (63 in) in the same species, respectively. The tails of bears are often considered a vestigial feature and can range from 3 to 22 cm (1.2 to 8.7 in).
Unlike most other land carnivorans, bears are plantigrade. They distribute their weight toward the hind feet, which makes them look lumbering when they walk. They are still quite fast, with the brown bear reaching 48 km/h (30 mph), although they are still slower than felines and canines. Bears can stand on their hind feet and sit up straight with remarkable balance. Bears' nonretractable claws are used for digging, climbing, tearing, and catching prey. Their ears are rounded.
Bears have an excellent sense of smell, better than the dogs (Canidae), or possibly any other mammal. This sense of smell is used for signalling between bears (either to warn off rivals or detect mates) and for finding food. Smell is the principal sense used by bears to find most of their food.
Distribution and habitat:
Bears are primarily found in the Northern Hemisphere, and with one exception, only in Asia, North America, and Europe. The single exception is the spectacled bear (Tremarctos ornatus); native to South America it inhabits the Andean region. The Atlas bear, a subspecies of the brown bear, was the only bear native to Africa. It was distributed in North Africa from Morocco to Libya, but has been extinct since around the 1870s. The most widespread species is the brown bear, which occurs from Western Europe eastwards through Asia to the western areas of North America. The American black bear is restricted to North America, and the polar bear is restricted to the Arctic Sea. All the remaining species are Asian.
With the exception of the polar bear, bears are mostly forest species. Some species, particularly the brown bear, may inhabit or seasonally use other areas, such as alpine scrub or tundra.
Behaviour:
Bears are generally diurnal, meaning that they are active for the most part during the day. The belief that they are nocturnal apparently comes from the habits of bears that live near humans, which engage in some nocturnal activities, such as raiding trash cans or crops while avoiding humans. The sloth bear of Asia is the most nocturnal of the bears, but this varies by individual, and females with cubs are often diurnal to avoid competition with males and nocturnal predators. Bears are overwhelmingly solitary and are considered to be the most asocial of all the Carnivora. Liaisons between breeding bears are brief, and the only times bears are encountered in small groups are mothers with young or occasional seasonal bounties of rich food (such as salmon runs
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