American Black Bear (Calgary Zoo Canadian Wilds Guide)

American Black Bear

Ursus americanus

Summary ²

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. American 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 by the IUCN to be globally threatened with extinction. 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.[1]

Throughout their range, habitats preferred by American black bears have a few shared characteristics. They are often found in areas with relatively inaccessible terrain, thick understory vegetation and large quantities of edible material (especially masts). The adaptation to woodlands and thick vegetation in this species may have originally been due to the American black bear having evolved alongside larger, more aggressive bear species, such as the extinct giant short-faced bear and the still-living grizzly bear, that monopolized more open habitats [33] and the historic presence of larger predators, such as Smilodon and the American lion, that could have preyed on American black bears. Although found in the largest numbers in wild, undisturbed areas and rural regions, American black bears can adapt to surviving in some numbers in peri-urban regions, as long as they contain easily accessible foods and some vegetative coverage.[4]

In most of the contiguous United States, American black bears today are usually found in heavily vegetated mountainous areas, from 400 to 3,000 m (1,300 to 9,800 ft) in elevation. For American black bears living in the American Southwest and Mexico, habitat usually consists of stands of chaparral and pinyon juniper woods. In this region, bears occasionally move to more open areas to feed on prickly pear cactus. At least two distinct, prime habitat types are inhabited in the Southeastern United States. American black bears in the southern Appalachian Mountains survive in predominantly oak-hickory and mixed mesophytic forests. In the coastal areas of the Southeast (such as Florida, the Carolinas and Louisiana), bears inhabit a mixture of flatwoods, bays and swampy hardwood sites.

In the northeast part of the range (United States and Canada), prime habitat consists of a forest canopy of hardwoods such as beech, maple, birch and coniferous species. Corn crops and oak-hickory mast are also common sources of food in some sections of the Northeast; small, thick swampy areas provide excellent refuge cover largely in stands of white cedar. Along the Pacific coast, redwood, Sitka spruce and hemlocks predominate as overstory cover. Within these northern forest types are early successional areas important for American black bears, such as fields of brush, wet and dry meadows, high tidelands, riparian areas and a variety of mast-producing hardwood species. The spruce-fir forest dominates much of the range of the American black bear in the Rockies. Important nonforested areas here are wet meadows, riparian areas, avalanche chutes, roadsides, burns, sidehill parks and subalpine ridgetops.

In areas where human development is relatively low, such as stretches of Canada and Alaska, American black bears tend to be found more regularly in lowland regions.[33] In parts of northeastern Canada, especially Labrador, American black bears have adapted exclusively to semi-open areas that are more typical habitat in North America for brown bears (likely due to the absence here of brown and polar bears, as well as other large carnivore species).[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).[33] Across its range, the greatest skull length for the species has been reportedly measured from 23.5 to 35 cm (9.3 to 13.8 in).[4] 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.[4] 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 Asian 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.

American 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.[35] 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).[36] American black bears have good eyesight and have been proven experimentally to be able to learn visual color discrimination tasks faster than chimpanzees and just as fast as domestic dogs. They are also capable of rapidly learning to distinguish different shapes such as small triangles, circles and squares.[37]

American 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. American black bears on the East Coast tend to be heavier on average than those on the West Coast, although American 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).[4][38]

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.[33] Adult American 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 American black bears averaged an estimated 115 kg (254 lb).[39][40] In Great Smoky Mountains National Park, adult males averaged 112 kg (247 lb) and adult females averaged 47 kg (104 lb) per one study.[41] In one of the largest studies on regional body mass, bears in British Columbia averaged 73.7 kg (162 lb) in 89 females and 103.1 kg (227 lb) in 243 males.[42] In Yellowstone National Park, a population study found that adult males averaged 119 kg (262 lb) and adult females averaged 67 kg (148 lb).[43] Black bears in north-central Minnesota averaged 69.9 kg (154 lb) in 163 females and 124.95 kg (275 lb) in 77 males.[44] In New York, the two sexes reportedly average 135 kg (298 lb) and 74 kg (163 lb), respectively.[45] It was found in Nevada and Lake Tahoe region that black bears closer to urban regions were significantly heavier than their arid-country dwelling counterparts, with males near urban areas averaging 138 kg (304 lb) against wild-land males which averaged 115.5 kg (255 lb) whereas peri-urban females averaged 97.9 kg (216 lb) against the average of 65.2 kg (144 lb) in wild-land ones.[46] In Waterton Lakes National Park, Alberta adults reportedly averaged 125 to 128 kg (276 to 282 lb).[47] 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.[35][48][49][50] Although they are the smallest bear species in North America, large males exceed the size of other bear species, except the brown bear and the polar bear.[35]

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.[51] Another notably outsized wild American 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.[51] The record-sized American black bear from New Jersey was shot in Morris County December 2011 and scaled 376.5 kg (830 lb).[52] Even larger, the most massive American 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.[53] The North American Bear Center, located in Ely, Minnesota, is home to the world's largest captive male and female American black bears. Ted, the male, weighed 431–453.5 kg (950–1,000 lb) in the fall of 2006.[54] Honey, the female, weighed 219.6 kg (484 lb) in the fall of 2007.[55]

Sources and Credits

(c) Michael Webber, some rights reserved (CC BY-NC-SA), https://www.flickr.com/photos/michaelwebber/5853583527/
Adapted by calgaryzoo from a work by (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Ursus_americanus

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