American Black Bear

The American black bear (Ursus americanus) is a medium-sized bear native to North America. It is the continent's smallest and most widely distributed bear species. Black bears are omnivores, with their diets varying greatly depending on season and location. They typically live in largely forested areas, but do leave forests in search of food. Sometimes they become attracted to human communities because of the immediate availability of food. The American black bear is the world's most common bear species.
It is listed by the International Union for Conservation of Nature (IUCN) as a least-concern species, due to its widespread distribution and a large population estimated to be twice that of all other bear species combined. Along with the brown bear, it is one of only two of the eight modern bear species not considered globally threatened with extinction by the IUCN. American black bears often mark trees using their teeth and claws as a form of communication with other bears, a behavior common to many species of bears.
== Description ==
The skulls of American black bears are broad, with narrow muzzles and large jaw hinges. In Virginia, the total length of adult bear skulls was found to average 262 to 317 mm (10.3 to 12.5 in). Across its range, greatest skull length for the species has been reportedly measured from 23.5 to 35 cm (9.3 to 13.8 in). Females tend to have slenderer and more pointed faces than males. Their claws are typically black or grayish-brown. The claws are short and rounded, being thick at the base and tapering to a point. Claws from both hind and front legs are almost identical in length, though the foreclaws tend to be more sharply curved. The paws of the species are relatively large, with a rear foot length of 13.7 to 22.5 cm (5.4 to 8.9 in), which is proportionately larger than other medium-sized bear species but much smaller than the paws of large adult brown, and especially polar, bears. The soles of the feet are black or brownish, and are naked, leathery, and deeply wrinkled. The hind legs are relatively longer than those of Asiatic black bears. The vestigial tail is usually 4.8 inches (120 mm) long. The ears are small and rounded, and are set well back on the head.
Black bears are highly dexterous, being capable of opening screw-top jars and manipulating door latches. They also have great physical strength. They have been known to turn over flat-shaped rocks weighing 310 to 325 pounds (141 to 147 kg) by flipping them over with a single foreleg. They move in a rhythmic, sure-footed way and can run at speeds of 25 to 30 miles per hour (40 to 48 km/h). Black bears have good eyesight and have been proven experimentally to be able to learn visual color discrimination tasks faster than chimpanzees and as fast as dogs. They are also capable of rapidly learning to distinguish different shapes such as small triangles, circles, and squares.
Black bear weight tends to vary according to age, sex, health, and season. Seasonal variation in weight is very pronounced: in autumn, their pre-den weight tends to be 30% higher than in spring, when black bears emerge from their dens. Black bears on the East Coast tend to be heavier on average than those on the West Coast, although black bears follow Bergmann's rule and bears from the Northwest are often slightly heavier than the bears from the Southeast. Adult males typically weigh between 57–250 kg (126–551 lb), while females weigh 33% less at 41–170 kg (90–375 lb).
In the state of California, studies have indicated that the average mass is 86 kg (190 lb) in adult males and 58 kg (128 lb) in adult females. Adult black bears in Yukon Flats National Wildlife Refuge in east-central Alaska were found to average 87.3 kg (192 lb) in males and 63.4 kg (140 lb) in females, whereas on Kuiu Island in southeast Alaska (where nutritious salmon are readily available) adult bears averaged an estimated 115 kg (254 lb). In Great Smoky Mountains National Park, adult males averaged 112 kg (247 lb) and adult females averaged 47 kg (104 lb) per one study. In Yellowstone National Park, a population study found that adult males averaged 119 kg (262 lb) and adult females averaged 67 kg (148 lb). In New York state, the two sexes reportedly average 135 kg (298 lb) and 74 kg (163 lb), respectively. Adults typically range from 120 to 200 cm (47 to 79 in) in head-and-body length, and 70 to 105 cm (28 to 41 in) in shoulder height. The typically small tail is 7.7–17.7 cm (3.0–7.0 in) long. Although they are the smallest species in North America, large males exceed the size of other bear species except the brown bear and polar bears.
The biggest wild American black bear ever recorded was a male from New Brunswick, shot in November 1972, that weighed 409 kg (902 lb) after it had been dressed, meaning it weighed an estimated 500 kg (1,100 lb) in life, and measured 2.41 m (7.9 ft) long. Another notably outsized wild black bear, weighing in at 408 kg (899 lb) in total, was the cattle-killer shot in December 1921 on the Moqui Reservation in Arizona. The record-sized bear from New Jersey was shot in Morris CountyDecember 2011 and scaled 376.5 kg (830 lb). Even larger, the most massive black bear recorded in Pennsylvania (one of six weighing over 363 kg (800 lb) shot in the last 15 years in the state) weighed in at 399 kg (880 lb) and was shot in November 2010 in Pike County. The North American Bear Center, located in Ely, Minnesota, is home to the world's largest captive male and female black bears. Ted, the male, weighed 431–453.5 kg (950–1,000 lb) in the fall of 2006. Honey, the female, weighed 219.6 kg (484 lb) in the fall of 2007.
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