American Black Bear (Priority species: Smokies Discovery Impact Day)

American Black Bear

Ursus americanus

Description ⁴

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 County December 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.

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 southwestern British Columbia. Albino specimens have also been recorded. Black coats tend to predominate in moist areas such as Maine, New York, Tennessee, Michigan and western Washington. Approximately 70% of all black bears are black, though only 50% of black bears in the Rocky Mountains 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.

In his book The Great Bear Almanac, Gary Brown summarized the predominance of black or brown/blond specimens by location:

Dietary habits ⁴

Generally, American black bears are largely crepuscular in foraging activity, though may actively feed at any time. Up to 85% of the black bear's diet consists of vegetation, though they tend to dig less than brown bears, eating far fewer roots, bulbs, corms and tubers than the latter species. 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 largely comprises fruits, especially berries and soft masts such as buds and drupes. During the autumn hyperphagia, feeding becomes virtually the full-time task of black bears. Hard masts become the most important part of the black bear's diet in autumn and may even partially dictate the species distribution. Favored masts such as hazelnuts, oak acorns and whitebark pine nuts may be consumed by the hundreds each day by a single black bear during fall. During the fall period, American black bears may also habitually raid the nut caches of tree squirrels. Also extremely important in fall are berries such as huckleberries and buffalo berries. 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.

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. Once the hive is breached, black bears will scrape the honeycombs together with their paws and eat them, regardless of stings from the bees. 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. However, the white-furred black bears of the islands of western Canada have a 30% greater success rate in catching salmon than their black-furred counterparts. Other fish including suckers, trout and catfish are readily caught when possible. Although black bears do not often engage in active predation of other large animals for much of the year, the species will regularly prey on mule and white-tailed deer fawns in spring, given the opportunity. Bears may catch the scent of hiding fawns when foraging for something else and then sniff them out and pounce. As the fawns reach 10 days of age, they can outmaneuver the bears and their scent is soon ignored until the next year. Black bear have also been recorded similarly preying on elk calves in Idaho and moose calves in Alaska.

Black bear predation on adult deer is rare but has been recorded. They may even hunt prey up to the size of adult female moose, which are considerably larger than themselves, by ambushing them. There is at least one record of a male black bear killing two bull elk over the course of six days by chasing them into deep snow banks which impeded their movements. In Labrador, black bears are exceptionally carnivorous, living largely off caribou, usually sickly, young or dead specimens, and rodents such as voles. This is believed to be due to a paucity of edible plant life in this sub-Arctic region and a local lack of competing large carnivores (including other bear species). 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 prefers 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. Vegetation around the carcass is usually matted down by black bears, and their droppings are frequently found nearby. 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.

Sources and Credits

(c) Michael Webber, some rights reserved (CC BY-NC-SA), https://www.flickr.com/photos/michaelwebber/5853583527/
(c) 116916927065934112165, some rights reserved (CC BY), uploaded by 116916927065934112165, https://picasaweb.google.com/116916927065934112165/INaturalist4#5780987346233114850
(c) oldbilluk, some rights reserved (CC BY-NC-SA), https://www.flickr.com/photos/oldbilluk/5961873541/
(c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/American_black_bear

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