American black bear

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American Black Bear
Conservation status
Least concern
Scientific classification
Kingdom: Animalia   Phylum: Chordata   Class: Mammalia   Order: Carnivora   Family: Ursidae   Genus: Ursus   Species: americanus
Binomial name
Ursus americanus Pallas, 1780

For the Eurasian Black Bear, see Asiatic Black Bear.

The American Black Bear (Ursus americanus) is the most common bear species native to North America.

It lives throughout much of the continent, from northern Canada and Alaska south into Mexico, from the Atlantic to the Pacific. This includes 40 of the 50 U.S. states and all Canadian provinces except Prince Edward Island. Populations in the east-central and southern United States remain in the protected mountains and woodlands of parks and preserves, though bears will occasionally wander outside the parks' boundaries and have set up new territories, in some cases on the margins of urban environments in recent years as their populations increase. Although there were probably once as many as two million black bears in North America long before European colonization, the population declined to a low of 200,000 as a result of habitat destruction and unrestricted hunting culls. By current estimates, more than 800,000 are living today on the continent [1].

Contents 1 Physical description 2 Habitat and behavior 3 Taxonomy and subspecies ranges 4 History and controversy 5 Legal status 6 Miscellaneous 7 See also 8 References 9 External links 10 Gallery

Physical description

The American Black Bear is about 1.8 m (6 feet) long. Females weigh between 40 and 180 kg (90 and 400 pounds); males weigh between 68 and 225 kg (150 and 500 pounds). Cubs usually weigh 200 to 450 g (between seven ounces and one pound) at birth. The adult has small eyes, rounded ears, a long snout, a large body, and a short tail. It has an excellent sense of smell. Though they generally have shaggy black hair, the coat can vary in color depending on the subspecies, from white through chocolate-brown, cinnamon-brown and blonde, found mostly west of the Mississippi River, to black in the east (the same is generally true in Canada, the border being between Manitoba and Ontario). Further adding to the confusion, they occasionally have a slight white chest blaze on either side of the river.

Although they are able to stand and walk on their hind legs, they usually stand or walk on all four legs; when they do stand, it is usually to get a better scent or look at something. Their characteristic shuffling gait results from walking flat-footed (called plantigrade), with the hind legs slightly longer than the front legs. Another reason for the apparent shuffle is that they commonly walk with a pacing gait. Unlike many quadrupeds, the legs on one side move together instead of alternating, much like a pacer horse. Each paw has five strong claws used for tearing, digging, and climbing. One blow from a powerful front paw can kill an adult elk.

Habitat and behavior

Black bears prefer forested and shrubby areas, but use wet meadows, high tidelands, ridgetops, burned areas, riparian areas, agricultural fields, and avalanche chutes. They also frequent swampy hardwood and conifer forests. Black bears sometimes hibernate during winter and may build dens in tree cavities, under logs or rocks, in banks, caves, or culverts, and in shallow depressions. After emerging from their winter dens in spring, they seek carion from winter-killed animals and new shoots of many plant species, especially wetland plants. In mountainous areas, they seek southerly slopes at lower elevations for forage and move to northerly and easterly slopes at higher elevations as summer progresses. Black bears use dense cover for hiding and thermal protection, as well as for bedding. They climb trees to escape danger and use forested areas as travel corridors.

Females generally reach breeding maturity at 3 to 4 years of age and with adequate nutrition can breed every 2 years. In poor quality habitat, they may not mature until 5-7 and may skip breeding cycles. Males are sexually mature at same age, but may not become large enough to win breeding rights until they are 4-5 years old (they have to be large enough to win fights with other males and be accepted by females). Mating is generally during summer, from Mid-June to mid-August with some variation depending on latitude, but with embryonic diapause (delayed implantation), the embryos do not begin to develop until the mother dens in the fall to hibernate through the winter months. Because of this delay, gestation can be 7 to 8 months, but actual development takes about 60 days. However, if food was scarce and the mother has not gained enough fat to sustain herself during hibernation as well as produce and feed cubs, the embryos do not develop.

The cubs are generally born in January or February. They are very small, about 10-14 ounces, and are blind, nearly hairless, and helpless when born. Two to three cubs are most common, though up to four and even five cubs has been documented. First-time mothers typically have only a single cub. The mother nurses the cubs with rich milk, and by spring thaw, when the bears start leaving their dens, the cubs are fur-balls of energy, inquisitive and playful. By this time they are about 4 to 8 pounds (2-4 kg). When their mother senses danger, she grunts to the cubs to climb high up a tree. They are weaned between July and September of their first year and stay with the mother through the first winter. The cubs become independent during their second summer (when they are 1.5 years old). At this time, the sow goes into estrus (heat) again.

Cub survival is totally dependent on the skill of the mother in teaching her cubs what to eat, where and how to forage (find food), where to den, and when and where to seek shelter from heat or danger.

American Black Bears are omnivores. They eat a wide variety of foods, relying most heavily on grasses, herbs, fruits, and mast. They also feed on carrion and insects (mainly for the larvae) such as carpenter ants (Campanotus spp.), yellow jackets (Vespula spp.), bees (Apidae), and termites (Isoptera), and raid bee's nests for honey.

They sometimes kill and eat small rodents and ungulate fawns. Like many animals, they seldom attack unless cornered or threatened, or wounded. They are less likely to attack humans than grizzly bears and typically have long since run for cover before one catches sight of them. Grizzly attacks are most often defensive, while black bear attacks on humans, although extremely rare, are often predatory. This makes feigning death when a black bear attacks ineffective. It is estimated that there have been only 56 documented killings of humans by black bears in North America in the past 100 years.

Black bears eat a great variety of vegetation and nuts, as shown in the list below. The list reflects the different types of habitat in which it is found, from prairie to swamps to both eastern and western types of forest.