The Black Bear

Black Bear Anatomy

The (North) 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.

Contents

• Sub-Species of Black Bear

• General Information on the Black Bear

• Skeleton and Muscles

• Fur

• Behaviour

-Social
-Reproductive
-Feeding

• Communication

Sub-Species of Black Bear

There are sixteen recognized subspecies of black bear:

• Olympic black bear

• New Mexico black bear

• Eastern black bear

• California black bear

• Haida Gwaii black bear

• Cinnamon bear

• Glacier bear

• Mexican black bear

• Florida black bear

• Newfoundland black bear

• Kermode bear/Spirit bear

• Louisiana black bear

• West Mexico black bear

• Kenai black bear

• Dall black bear

• Vancouver Island black bear

   

General Information on the Black Bear

 

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. Adult males typically weigh between 57–250 kg, while females weigh 33% less at 41–170 kg.

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Adults typically range from 120 to 200 cm in head-and-body length, and 70 to 105 cm in shoulder height. The typically small tail is 7.7–17.7 cm long. Although they are the smallest species in North America, large males exceed the size of other bear species except the brown 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 after it had been dressed, meaning it weighed an estimated 500 kg in life, and measured 2.4 m long. 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 in the autumn of 2006. Honey, the female, weighed 219.6 kg in the autumn of 2007.

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Skeleton and Muscles

 

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. Across its range, greatest skull length for the species has been reportedly measured from 23.5 to 35 cm. Females tend to have more slender and pointed faces than males.

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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 sizeable, with a rear foot length of 13.7 to 22.5 cm, being proportionly 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 leathery and deeply wrinkled. The hind legs are relatively longer than those of Asiatic black bears. The ears are small and rounded, and are set well back on the head.

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Black bears are highly dexterous, being capable of opening screw-top jars and manipulating door latches. They also have great physical strength. Even bear cubs have been known to turn over flat-shaped rocks weighing 310 to 325 pounds by flipping them over with a single foreleg. They move in a rhythmic, surefooted way and can run at speeds of 25–30 mph (40–50 km/h). Black bears have good eyesight, and have been proven experimentally to be able to learn visual discrimination tasks based on color 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.

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Fur

 

The fur is soft, with dense underfur and long, coarse, thick guard hairs. The fur is not as shaggy or coarse as that of brown bears. American black bear skins can be distinguished from those of Asiatic black bears by the lack of a white mark on the chin and hairier footpads. Despite their name, black bears show a great deal of color variation. Individual coat colors can range from white, blond, cinnamon, or light brown to dark chocolate brown or to jet black, with many intermediate variations existing. Bluish tinged black bears occur along a portion of coastal Alaska and British Columbia. White to cream colored black bears occur in coastal islands and the adjacent mainland of south-western British Columbia. Albino specimens have also been recorded. Black coats tend to predominate in moist areas such as New England, New York, Tennessee, Michigan and western Washington. Approximately 70% of all black bears are black. Many black bears in Northwestern North America are cinnamon, blond or light brown in color, and thus may sometimes be mistaken for grizzly bears. Grizzly (and other types of brown) bears can be distinguished by their shoulder hump, larger size and broader, more concave skull.

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Behaviour (Social, Reproductive, Feeding)

 

Social

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American black bears tend to be territorial and non-gregarious in nature. However, at abundant food sources (i.e. spawning salmon or garbage dumps) black bears may congregate and dominance hierachies form, with the largest, most powerful males dominating the most fruitful feeding spots. They mark their territories by rubbing their bodies against trees and clawing at the bark. Annual ranges held by mature male black bears tend to be very large but there is some variation. Black bears are excellent and strong swimmers, doing so for pleasure and to feed (largely on fish). Black bears climb regularly to feed, escape enemies or to hibernate.

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Reproductive

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Sows usually produce their first litter at the age of 3–5 years. Sows living in more developed areas tend to get pregnant at younger ages. The breeding period usually occurs in the June–July period, though it can extend to August in the species' northern range. The breeding period lasts for 2–3 weeks. Both sexes are promiscuous. Males try to mate with several females but may large, dominant ones may violently claim a female if another mature male comes near. Sows tend to be short tempered with their mates after copulating.

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The gestation period lasts 235 days, and litters are usually born in late January to early February. Litters usually consist of two cubs, though litters of 6 have been recorded. At birth, cubs weigh 280–450 g, and measure 20.5 cm in length. They are born with fine, gray, downlike hair, and their hind quarters are underdeveloped. They typically open their eyes after 28–40 days, and begin walking after 5 weeks. Cubs are dependent on their mother's milk for 30 weeks, and will reach independence at 16–18 months. They reach sexual maturity at the age of three years, and attain their full growth at 5 years.

 

Feeding

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Up to 85% of the black bear's diet consists of vegetation, though they tend to dig less than brown bears. When initially emerging from hibernation, they will seek to feed on carrion from winter-killed animals and newborn ungulates. As the spring temperature warms, black bears seek new shoots of many plant species, especially new grasses, wetland plants and forbs. Young shoots and buds from trees and shrubs during the spring period are also especially important to black bears emerging from hibernation, as they assist in rebuilding muscle and strengthening the skeleton and are often the only digestible foods available at that time. During summer, the diet is comprised largely by fruits. Hard masts become the most important part of the black bear's diet in autumn and may even partially dictate the species distribution.

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Black bears living in areas near human settlements or around a considerable influx of recreational human activity often come to rely on foods inadvertently provided by humans, especially during summertime. These include refuse, birdseed, agricultural products and honey from apiaries.

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The majority of the black bear's animal diet consists of insects such as bees, yellow jackets, ants and their larvae. Black bears are also fond of honey, and will gnaw through trees if hives are too deeply set into the trunks for them to reach them with their paws. Black bears that live in northern coastal regions (especially the Pacific coast) will fish for salmon during the night, as their black fur is easily spotted by salmon in the daytime. Although black bears do not often engage in active predation of other large animals for much of the year, the species will also regularly prey on mule and white-tailed deer fawns in spring given the opportunity.

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 Like brown bears, black bears try to use surprise to ambush their prey and target the sickly animals in herds. Once a deer fawn is captured, it is frequently torn apart alive while feeding. If able to capture a mother deer in spring, the bear frequently begins feeding on the udder of lactating females, but generally prefer meat from the viscera. Black bears often drag their prey to cover, preferring to feed in seclusion. The skin of large prey is stripped back and turned inside out with the skeleton usually left largely intact. Unlike wolves and coyotes, black bears rarely scatter the remains of their kills. Black bears may attempt to cover remains of larger carcasses, though they do not do so with the same frequency as cougars and grizzly bears. They will readily consume eggs and nestlings of various birds and can easily access many tree nests, even the huge nest of the bald eagle. Black bears have been reported stealing deer and other animals from human hunters.

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Communication

 

In his Great Bear Almanac, Gary Brown lists 20 different sounds in eight different contexts. Sounds expressing aggression include growls, woofs, snorts, bellows and roars. Sounds expressing contentment include mumbles, squeaks and pants.