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 global 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.^[1]

Taxonomy and evolution

Despite living in North America, American black bears are not closely related to brown bears and polar bears; genetic studies reveal that they split from a common ancestor 5.05 million years ago (mya).^[3] Both American and Asian black bears are considered sister taxa, and are more closely related to each other than to other species of bear.^[3][4] Reportedly, the sun bear is also a relatively recent split from this lineage.^[5]

A small primitive bear called Ursus abstrusus is the oldest known North American fossil member of the genus Ursus, dated to 4.95 mya.^[6] This suggests that U. abstrusus may be the direct ancestor of the American black bear, which evolved in North America.^[3][7] Although Wolverton and Lyman still consider U. vitabilis an "apparent precursor to modern black bears",^[8] it has also been placed within U. americanus.^[7]

The ancestors of American black bears and Asiatic black bears diverged from sun bears 4.58 mya. The American black bear then split from the Asian black bear 4.08 mya.^[3][9] The earliest American black bear fossils, which were located in Port Kennedy, Pennsylvania, greatly resemble the Asiatic species,^[10] though later specimens grew to sizes comparable to grizzlies.^[11] From the Holocene to present, American black bears seem to have shrunk in size,^[3] but this has been disputed because of problems with dating these fossil specimens.^[8]

The American black bear lived during the same period as short-faced bears (Arctodus simus and A. pristinus) and the Florida spectacled bear (Tremarctos floridanus). These Tremarctine bears evolved from bears that had emigrated from Asia to North America 7–8 ma.^[12] The short-faced bears are thought to have been heavily carnivorous and the Florida spectacled bear more herbivorous,^[13] while the American black bears remained arboreal omnivores, like their Asian ancestors. The black bear's generalist behavior allowed it to exploit a wider variety of foods and has been given as a reason why, of these three genera, it alone survived climate and vegetative changes through the last ice age while the other more specialized North American predators became extinct. However, both Arctodus and Tremarctos had survived several other ice ages. After these prehistoric ursids became extinct during the last glacial period 10,000 years ago, black bears were probably the only bear present in much of North America until the migration of brown bears to the rest of the continent.^[11]

Hybrids

American black bears are reproductively compatible with several other bear species, and have occasionally produced hybrid offspring. According to Jack Hanna's Monkeys on the Interstate, a bear captured in Sanford, Florida, was thought to have been the offspring of an escaped female Asian black bear and a male American black bear.^[14] In 1859, a black bear and a Eurasian brown bear were bred together in the London Zoological Gardens, but the three cubs died before they reached maturity. In The Variation of Animals and Plants under Domestication Charles Darwin noted:

In the nine-year Report it is stated that the bears had been seen in the zoological gardens to couple freely, but previously to 1848 most had rarely conceived. In the reports published since this date three species have produced young (hybrids in one case), ...^[15]

A black bear shot in autumn 1986 in Michigan was thought by some to be a black bear/grizzly bear hybrid, due to its unusually large size and its proportionately larger braincase and skull. DNA testing was unable to determine whether it was a large black bear or grizzly.^[16]

Subspecies

Listed alphabetically.^[17]

American black bear sub-species

Sub-species name	Common name	Distribution	Description
Ursus americanus altifrontalis	Olympic black bear	Pacific Northwest coast from central British Columbia through northern California and inland to the tip of northern Idaho and British Columbia
Ursus americanus amblyceps	New Mexico black bear	Native to Colorado, New Mexico, west Texas, the eastern half of Arizona into northern Mexico, and southeastern Utah
Ursus americanus americanus	Eastern black bear	Eastern Montana to the Atlantic coast, from Alaska south and east through Canada to Maine and south to Texas. Thought to be increasing in some regions.	Common to Eastern Canada and U.S. wherever suitable habitat is found. A large-bodied subspecies, almost all specimens have black fur. May very rarely sport a white blaze on chest.
Ursus americanus californiensis	California black bear	Mountain ranges of southern California, north through the Central Valley to southern Oregon	Able to live in varied climates: found in temperate rainforest in the north and chaparral shrubland in the south. Small numbers may feature a cinnamon brown fur.
Ursus americanus carlottae	Haida Gwaii black bear, Queen Charlotte black bear	Haida Gwaii/Queen Charlotte Islands and Alaska	Generally larger than its mainland counterparts with a huge skull and molars, and is found only as a black color phase[18]
Ursus americanus cinnamomum	Cinnamon bear	Colorado, Idaho, western Montana, and Wyoming, eastern Washington and Oregon, northeastern Utah	Has brown or red-brown fur, reminiscent of cinnamon.
Ursus americanus emmonsii	Glacier bear	Southeast Alaska. Stable.	Distinguished by the fur of its flanks being silvery gray with a blue luster[19]
Ursus americanus eremicus	Mexican black bear	Northeastern Mexico and US borderlands with Texas. Very endangered.	Most often found in Big Bend National Park and the desert border with Mexico. Numbers unknown in Mexico, but presumed very low.
Ursus americanus floridanus	Florida black bear	Florida, southern Georgia, and Alabama	Has a light brown nose and shiny black fur. A white chest patch is also common. An average male weighs 136 kg (300 lb).
Ursus americanus hamiltoni	Newfoundland black bear	Newfoundland	Generally bigger than its mainland relatives, ranging in size from 90 to 270 kg (200 to 600 lb) and averaging 135 kg (298 lb). It has one of the longest hibernation periods of any bear in North America.[20] Known to favor foraging in fields of Vaccinium species.
Ursus americanus kermodei	Kermode bear, spirit bear	Central coast of British Columbia	Approximately 10% of the population of this subspecies have white or cream-colored coats due to a recessive gene and are called "kermodes" or "spirit bears". The other 90% appear as normal-colored black bears.[21]
Ursus americanus luteolus	Louisiana black bear	Eastern Texas, Louisiana, southern Mississippi. Threatened (federal list).	Has relatively long, narrow, and flat skull, and proportionately large molars[22] Prefers hardwood bottom forests and bayous as habitat
Ursus americanus machetes	West Mexico black bear	North-central Mexico
Ursus americanus perniger	Kenai black bear	Kenai Peninsula, Alaska
Ursus americanus pugnax	Dall black bear	Alexander Archipelago, Alaska
Ursus americanus vancouveri	Vancouver Island black bear	Vancouver Island, British Columbia	Found in the northern section of the island, but occasionally will appear in the suburbs of Victoria metropolitan area

Distribution and population

Historically, black bears occupied the majority of North America's forested regions. Today, they are primarily limited to sparsely settled, forested areas.^[23] Black bears currently inhabit much of their original Canadian range, though they seldom occur in the southern farmlands of Alberta, Saskatchewan, and Manitoba; they have been extinct in Prince Edward Island since 1937.^[24] The total Canadian black bear population is between 396,000 and 476,000,^[25] based on surveys taken in the mid-1990s in seven Canadian provinces, though this estimate excludes black bear populations in New Brunswick, Northwest Territories, Nova Scotia, and Saskatchewan. All provinces indicated stable populations of black bears over the last decade.^[23]

The current range of black bears in the United States is constant throughout most of the northeast, and down in the Appalachian Mountains almost continuously from Maine to north Georgia, the northern midwest, the Rocky Mountain region, the west coast and Alaska.^[24] However it becomes increasingly fragmented or absent in other regions. Despite this, black bears in those areas seems to have expanded their range during the last decade, such as with recent sightings in Ohio^[24] and southern Indiana, though these probably do not represent stable breeding populations yet. Surveys taken from 35 states in the early 1990s indicate that black bears are either stable or increasing, except in Idaho and New Mexico. The overall population of black bears in the United States has been estimated to range between 339,000 and 465,000,^[26] though this excludes populations from Alaska, Idaho, South Dakota, Texas, and Wyoming, whose population sizes are unknown.^[23] In the state of Maine, there are an estimated 30,000 black bears, making it the largest black bear population in the Contiguous United States.^[27][28]

As of 1993, known Mexican black bear populations existed in four areas, though knowledge on the distributions of populations outside those areas have not been updated since 1959. Mexico is the only country where the black bear is classified as "endangered".^[23]

There have been several sightings quite far away from where the black bear is normally found, such as Union County, North Carolina^[29][30] and western Nebraska.^[31]

Habitat

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 black bear having evolved alongside larger, more aggressive bear species, such as the extinct short-faced bear and the still living grizzly bear, that monopolized more open habitats ^[32] and the historic presence of larger predators such as smilodon and the American lion that could have preyed on black bears. Although found in the largest numbers in wild, undisturbed areas and rural regions, 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.^[5]

In most of the contiguous United States, black bears today are usually found in heavily vegetated mountainous areas, from 400 to 3,000 m (1,300 to 9,800 ft). For 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 Southeast United States. 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, and 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 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 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.^[32] In parts of northeastern Canada, especially Labrador, 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).^[5]

Description

Build

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).^[32] 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).^[5] Females tend to have more slender and 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 sizeable, with a rear foot length of 13.7 to 22.5 cm (5.4 to 8.9 in), being proportionly larger than other medium-sized bear species but much smaller than the paws of large adult brown and especially polar bears.^[5] 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 vestigal tail is usually 4.8 inches (12 cm) 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.^[34] They move in a rhythmic, sure-footed way and can run at speeds of 25–30 mph (40–50 km/h).^[35] 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.^[36]

Size

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).^[5][37]

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.^[32] 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).^[38][39] In Great Smoky Mountains National Park, adult males averaged 112 kg (247 lb) and adult females averaged 47 kg (104 lb) per one study.^[40] In Yellowstone National Park, a population study found that adult males averaged 119 kg (262 lb) and adult females averaged 67 kg (148 lb).^[41] In New York state, the two sexes reportedly average 135 kg (298 lb) and 74 kg (163 lb), respectively.^[42] 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.^{[34][43][44][45]} 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.^[34]

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.^[46] 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.^[46] The record-sized bear from New Jersey was shot in Morris County December 2011 and scaled 376.5 kg (830 lb).^[47] 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.^[48] 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.^[49] Honey, the female, weighed 219.6 kg (484 lb) in the fall of 2007.^[50]

Pelage

The fur is soft, with dense underfur and long, coarse, thick guard hairs.^[34] The fur is not as shaggy or coarse as that of brown bears.^[51] 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.^[52] 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.^[53] 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.^[34] 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.^[54]

In his book The Great Bear Almanac, Gary Brown summarized the predominance of black or brown/blond specimens by location:^[34]

Color variations of black bears by location
Location	Color breakdown
Michigan	100% black
Minnesota	94% black, 6% brown
New England	100% black
New York	100% black
Tennessee	100% black
Washington (coastal)	99% black, 1% brown or blonde
Washington (inland)	21% black, 79% brown or blonde
Yosemite National Park	9% black, 91% brown or blonde

Behavior

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.^[35] A black bear has better eyesight and a better sense of hearing compared to humans. Their keenest sense is the sense of smell, which is about seven times greater than a dog's.^[55] 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 hierarchies form, with the largest, most powerful males dominating the most fruitful feeding spots.^[56] 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. On Long Island off the coast of Washington, ranges average 5 sq mi (13 km²), whereas on the Ungava Peninsula in Canada ranges can average up to 1,000 sq mi (2,600 km²), with some male bears traveling as far as 4,349 sq mi (11,260 km²) in times of food shortages.^[5][56] Black bears are excellent and strong swimmers, doing so for pleasure and to feed (largely on fish). Black bears climb trees regularly to feed, escape enemies and to hibernate. Half of bear species are habitually arboreal (the most arboreal species, the American and Asian black bears and the sun bear, being fairly closely related).^[5] Their arboreal abilities tend to decline with age.^[35] Black bears may be active at any time of the day or night, although mainly forage by night. Bears living near human habitations tend to be more extensively nocturnal and bears living near brown bears tend to be more extensively diurnal.^[5][32]

Reproduction and development

Sows usually produce their first litter at the age of 3–5 years.,^[35] with those living in more developed areas tending to get pregnant at younger ages.^[57] 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 months. Both sexes are promiscuous. Males try to mate with several females but large, dominant ones may violently claim a female if another mature male comes near.^[32] Sows tend to be short tempered with their mates after copulating. The fertilized eggs undergo delayed development and do not implant in the female’s womb until November. The gestation period lasts 235 days, and litters are usually born in late January to early February. Litter size is between one and six cubs; typically two or three.^[58] At birth, cubs weigh 280–450 g (0.62–0.99 lb), and measure 20.5 cm (8.1 in) in length. They are born with fine, gray, down-like 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. At the age of six weeks, they attain 900 g (2.0 lb), by 8 weeks they reach 2.5 kg (5.5 lb) and by the age of 6 months they weigh 18 to 27 kg (40 to 60 lb). They reach sexual maturity at the age of three years, and attain their full growth at 5 years.^[35]

Longevity and mortality

The average lifespan in the wild is 18 years, though it is quite possible for wild specimens to survive for more than 23 years.^[54] The record age of a wild specimen was 39 years,^[59] while that in captivity was 44 years.^[34] Average annual survival rates for adult bears is variable, ranging from 86% in Florida to 73% in Virginia and North Carolina.^[32] In Minnesota, 99% of wintering adult bears were able to survive the hibernation cycle in one study.^[32] Remarkably, a study of black bears in Nevada found that the amount of annual mortality of a population of bears in wilderness areas was 0%, whereas in developed areas in the state this figure rose to 83%.^[5] Survival in sub-adults is generally less assured. In Alaska, only 14–17% of sub-adult males and 30–48% of sub-adult females were found in a study to survive to adulthood.^[32] Across the range, the estimated amount of cubs who survive past their first year is 60%.^[5]

With the exception of the rare confrontation with an adult brown bear or gray wolf pack, adult black bears are not usually subject to natural predation.^[32] However, as evidenced by scats with fur inside of them and the recently discovered carcass of an adult sow with puncture marks in the skull, black bears may occasionally have fallen and still do fall prey to jaguars such as the sole extant jaguar in the United States, El Jefe, in the southern parts of their range. In such scenarios, the big cat would have the advantage if it ambushed the bear, killing it with a crushing bite to the back of the skull.^[60] Black bear cubs tend to be more vulnerable to predation than adults. Known predators of bear cubs have included bobcats, coyotes, cougars, wolves, brown bears and other bears of their own species.^[5][32] Many of these will stealthily snatch small cubs right from under the sleeping mother. There is a single record of a golden eagle snatching a yearling cub.^[5] Once out of hibernation, mother bears may be able to fight off most potential predators.^[32] Even cougars will be displaced by an angry mother bear if they are discovered stalking the cubs.^[61] Flooding of dens after birth may also occasionally kill newborn cubs. However, in current times, American black bears fatalities are overwhelmingly attributable to human activities. Seasonally, tens of thousands of black bears are hunted legally across North America, with many more being illegally poached or trapped. Auto-collisions also may claim many black bear lives annually.^[5][32]

Hibernation

Black bears were once not considered true or "deep" hibernators, but because of discoveries about the metabolic changes that allow black bears to remain dormant for months without eating, drinking, urinating, or defecating, most biologists have redefined mammalian hibernation as "specialized, seasonal reduction in metabolism concurrent with scarce food and cold weather". Black bears are now considered highly efficient hibernators.^[62][63] The physiology of American black bears in the wild is closely related to that of bears in captivity. Understanding the physiology of bears in the wild is vital to the bear's success in captivity.^[64]

The bears enter their dens in October and November, although in the southernmost areas of their range (i.e. Florida, Mexico, the Southeastern United States), only pregnant females and mothers with yearling cubs will enter hibernation.^[5] Prior to that time, they can put on up to 14 kg (30 lb) of body fat to get them through the several months during which they fast. Hibernation in black bears typically lasts 3–8 months, depending on regional climate.^[18][65]

Hibernating bears spend their time in hollowed-out dens in tree cavities, under logs or rocks, in banks, caves, or culverts, and in shallow depressions. Although naturally-made dens are occasionally used, most dens are dug out by the bear itself.^[54] Females have been shown to be pickier in their choice of dens, in comparison to males.^[66]

During their time in hibernation, bears' heart rate drops from 40–50 beats per minute to 8 beats per minute and metabolic rate can drop to a quarter of a bear’s (non-hibernating) basal metabolic rate (BMR). These reductions in metabolic rate and heart rate do not appear to decrease the bear's ability to heal injuries during hibernation.^[67]

The hibernating American black bear does not display the same rate of muscle and bone atrophy relative to other nonhibernatory animals that are subject to long periods of inactivity, due to ailment or old age.^[68][69] A hibernating black bear loses approximately half the muscular strength to that of a well-nourished, inactive human. The bear’s bone mass does not change in geometry or mineral composition during hibernation, this implies that the bear’s conservation of bone mass during hibernation is due to a biological mechanism.^[70] During hibernation bears retain all excretory waste, leading to the development of a hardened mass of fecal material in the colon known as a fecal plug.^[71] A special hormone, leptin is released into the black bear's systems, to suppress appetite.The retention of waste during hibernation (specifically in minerals such as calcium) may play a role in the bear’s resistance to atrophy.^[68] The body temperature of the American black bear does not drop significantly, like other mammalian hibernators (staying around 35 degrees Celsius) and they remain somewhat alert and active. If the winter is mild enough, they may wake up and forage for food. Females also give birth in February and nurture their cubs until the snow melts.^[72] During winter, black bears consume 25–40% of their body weight.^[73] The footpads peel off while they sleep, making room for new tissue.

Many of the physiological changes a bear exhibits during hibernation are retained slightly post-hibernation. Upon exiting hibernation, bears retain a reduced heart rate and basal metabolic rate. The metabolic rate of a hibernating bear will remain at a reduced level for up to 21 days after hibernation.^[74] After emerging from their winter dens in spring, they wander their home ranges for two weeks so that their metabolism accustoms itself to the activity. 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.

Dietary habits

Generally, American black bears are largely crepuscular in foraging active, though may actively feed at any time.^[56] Up to 85% of the black bear's diet consists of vegetation,^[35] though they tend to dig less than brown bears, eating far fewer roots, bulbs, corms and tubers than the latter species.^[53] 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.^[73] 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.^[75] During summer, the diet is comprised largely by fruits, especially berries and soft masts such as buds and drupes. During the autumn hyperphagia, feeding becomes pretty much 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.^[5][32] During the fall period, American black bears may also habitually raid the nut caches of tree squirrels.^[73] Also extremely important in fall are berries such as huckleberries and buffalo berries.^[5] 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.^[54]

The majority of the black bear's animal diet consists of insects such as bees, yellow jackets, ants and their larvae.^[73] 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.^[46] 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.^[76] Other fish including suckers, trout and catfish are readily caught when possible.^[77] 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.^[78][79][80] In addition they have been recorded similarly preying on elk calves in Idaho^[81] and moose calves in Alaska.^[82]

Black bear predation on adult deer is rare but has been recorded.^[83][84][85] They may even hunt prey up to the size of adult female moose, which are considerably larger than themselves, by ambushing them.^[86] 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 where their movement is impeded. In Labrador, black bears are exceptionally carnivorous, living largely off of 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).^[54] 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.^[79] 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. 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.^[87] 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.^[35] Black bears have been reported stealing deer and other animals from human hunters.

Interspecific predatory relationships

Over much of their range, black bears are assured scavengers that can intimidate, using their large size and considerable strength, and if necessary dominate other predators in confrontations over carcasses. However, in occasions where they encounter the Kodiak or the grizzly bears, the larger two brown sub-species dominate them. Black bears tend to escape competition from brown bears by being more active in the daytime, and living in more densely forested areas. Violent interactions resulting in the deaths of black bears have been recorded in Yellowstone National Park.^[88][89]

Black bears do compete with cougars over carcasses. Like brown bears, they will sometimes steal kills from cougars. One study found that both bear species visited 24% of cougar kills in Yellowstone and Glacier National Parks, usurping 10% of carcasses.^[90][91] Another study found that black bears visited 48% of cougar kills in summer in Colorado, and 77% of kills in California. As a result, the cats spend more time killing and less time feeding on each kill.^[92][93]

Black bear interactions with wolves are much rarer than with brown bears, due to differences in habitat preferences. The majority of black bear encounters with wolves occur in the species′ northern range, with no interactions being recorded in Mexico. Despite the black bear being more powerful on a one-to-one basis, packs of wolves have been recorded to kill black bears on numerous occasions without eating them. Unlike brown bears, black bears frequently lose against wolves in disputes over kills.^[94] Wolf packs typically kill black bears when the large animals are in their hibernation cycle.^[37]

There is at least one record of a black bear killing a wolverine in a dispute over food in Yellowstone National Park.^[95] Anecdotal cases of alligator predation on bears have been reported, though such cases may involve assaults on cubs.^[96]

Relationships with humans

In folklore, mythology and culture

Black bears feature prominently in the stories of some of America's indigenous peoples. One tale tells of how the black bear was a creation of the Great Spirit, while the grizzly was created by the Evil Spirit.^[97] In the mythology of the Haida, Tlingit, Tsimshian people of the Northwest Coast, mankind first learned to respect bears when a girl married the son of black bear Chieftain.^[98] In Kwakiutl mythology, black and brown bears became enemies when Grizzly Bear Woman killed Black Bear Woman for being lazy. Black Bear Woman's children, in turn, killed Grizzly Bear Woman's own cubs.^[99] The Navajo believed that the Big Black Bear was chief among the bears of the four directions surrounding Sun's house, and would pray to it in order to be granted its protection during raids.^[100]

Morris Michtom, the creator of the teddy bear, was inspired to make the toy when he came across a cartoon of Theodore Roosevelt refusing to shoot a black bear cub tied to a tree.^[101] Winnie the Pooh was named after Winnipeg, a female black bear cub that lived at London Zoo from 1915 until her death in 1934.^[102] A black bear cub who in the spring of 1950 was caught in the Capitan Gap fire was made into the living representative of Smokey Bear, the mascot of the United States Forest Service.^[103]

The American black bear is the mascot of The University of Maine and Baylor University, where the university houses two live black bears on campus.

Sleeping Bear Dunes is named after a Native American legend, where a female bear and her cub swam across Lake Michigan. Exhausted from their journey, the bears rested on the shoreline and fell sound asleep. Over the years, the sand covered them up, creating a huge sand dune.

Attacks on humans

Although an adult bear is quite capable of killing a human, American black bears typically avoid confronting humans when possible. Unlike grizzly bears, which became a subject of fearsome legend among the European settlers of North America, black bears were rarely considered overly dangerous, even though they lived in areas where the pioneers had settled. Black bears rarely attack when confronted by humans, and usually limit themselves to making mock charges, emitting blowing noises and swatting the ground with their forepaws. The number of black bear attacks on humans is higher than those of the brown bear in North America, though this is largely because the black species considerably outnumbers the brown rather than greater aggressiveness.

Compared to brown bear attacks, aggressive encounters with black bears rarely lead to serious injury. However, the majority of black bear attacks tend to be motivated by hunger rather than territoriality, and thus victims have a higher probability of surviving by fighting back rather than submitting. Unlike grizzlies, female black bears do not display the same level of protectiveness to their cubs, and seldom attack humans in their vicinity.^[53] However, occasionally, attacks by protective mothers do occur.^[32] The worst recorded fatality incident occurred in May 1978, in which a black bear killed three teenagers who were fishing in Algonquin Park in Canada.^[104] Another exceptional, spree-like attack occurred in August 1997 in Liard River Hot Springs Provincial Park in Canada, when an emaciated black bear attacked a child and mother, killing the mother as well as an adult man who tried to intervene. This bear was shot while mauling a fourth victim.^[105][106]

The majority of attacks happened in national parks, usually near campgrounds, where the bears had become habituated to close human proximity and food conditioned.^[53] Out of 1,028 incidents of black bears acting aggressively toward people, 107 resulted in injury, were recorded from 1964 to 1976 in the Great Smoky Mountains National Park, and occurred mainly in tourist hotspots where people regularly fed the bears handouts.^[104] In almost every case where open dumps or handouts that had previously attracted black bears were ceased, the amount of aggressive encounters with bears have decreased precipitously over time.^[32] However, in the aforementioned case of the spree attack in Liard River Hot Springs, the attacking bear was believed to have been previously almost fully dependent on a local garbage dump that had closed and was starving as a result of the loss of that food source.^[105] Attempts to relocate bears are typically unsuccessful, as black bears seem to be able to return to their home range even without familiar landscape cues.^[32]

On October 27, 2009, Canadian wildlife experts and managers for Cape Breton Highlands National Park thought Taylor Mitchell's suspect of her predatory attack on the Skyline Trail was a black bear at first, but they soon realized it was a pack of coyotes.^[107]

Livestock and crop predation

A limitation of food sources in early spring and wild berry and nut crop failures during summer months may be contributing factors to black bears regularly feeding from commercial human-based food sources. Crops are frequently eaten by these bears, especially during autumn hyperphagia when natural foods are scarce. Favored crops may include apples, oats and corns.^[5] Black bears can do extensive damage in some areas of the northwestern United States by stripping the bark from trees and feeding on the cambium. Livestock depredations by black bears occur mostly in spring. Though black bears have the capacity to (and occasionally do) hunt adult cattle and horses, they seem to prefer smaller, more easily overwhelmed prey such as sheep, goats, calves, and pigs. They normally kill by biting the neck and shoulders, though they may break the neck or back of prey with blows from the paws. Evidence of a bear attack includes claw marks and is frequently found on the neck, back, and shoulders of larger animals. Surplus killing of sheep and goats are common. Bears have been known to frighten livestock herds over cliffs, causing injuries and death to many animals; whether or not this is intentional is not known.^[87] Occasionally, pets, especially dogs, which are most prone to harass a bear, are killed by black bears.^[108] It is not recommended to use unleashed dogs as a deterrent from bear attacks. Although large, aggressive dogs sometimes cause a bear to run, if pressed, angry bears frequently turn the tables and end up chasing the dog in return. A bear in pursuit of a pet dog has the potential to threaten both canid and human lives.^[109][110]

Bear awareness in towns

In an effort to help prevent conflicts with bears, many towns in British Columbia developed bear aware programs. The main premise of these programs is to teach humans to manage foods that attract bears. Keeping garbage securely stored, harvesting fruit when ripe, securing livestock behind electric fences, and storing pet food indoors are all measures promoted by bear aware programs. Revelstoke, British Columbia is a community that demonstrates the success of this approach. Before the community had an education program, an average of 27 bears were killed in Revelstoke each year; after the program began, the average mortality has dropped to just 7 bears per year.^[111] See Revelstoke Bear Aware for more information.

Hunting and exploitation

Hunting

Historically, black bears were hunted by both Native Americans and European settlers. Some Native American tribes, in admiration for the black bear's intelligence, would decorate the heads of bears they killed with trinkets, and place them on blankets. Tobacco smoke would be wafted into the disembodied head's nostrils by the hunter that dealt the killing blow, who would compliment the animal for its courage.^[46] The Kutchin typically hunted black bears during their hibernation cycle. Unlike the hunting of hibernating grizzlies, which was fraught with danger, black bears took longer to awaken, and was thus safer and easier.^[112] During the European colonisation of eastern North America, thousands of black bears were hunted for their meat, fat and fur.^[4] Theodore Roosevelt wrote extensively on black bear hunting in his Hunting the Grisly and other sketches, in which he stated "in [a black bear] chase there is much excitement, and occasionally a slight spice of danger, just enough to render it attractive; so it has always been eagerly followed". He wrote that black bears were difficult to hunt by stalking, due to their habitat preferences, though were easy to trap. Roosevelt described how, in the southern states, planters regularly hunted black bears on horseback with hounds. General Wade Hampton was known to have been present at 500 successful black bear hunts, two thirds of which he killed personally. He killed thirty or forty black bears with only a knife, which he would use to stab the bears between the shoulder blades while they were distracted by his hounds.^[86] Unless well trained, horses were often useless in black bear hunts, as they often bolted when the bears stood their ground.^[46] In 1799, 192,000 black bear skins were exported from Quebec. In 1822, 3,000 skins were exported from the Hudson's Bay Company.^[113] In 1992, untanned, fleshed and salted black bear hides were sold for an average of $165.^[114]

In Canada, black bears are considered as both a big game and furbearer species in all provinces save for New Brunswick and Northwest Territories, where they are only classed as a big game species. There are around 80,900 licensed black bear hunters in all of Canada. Canadian black bear hunts take place in the fall and spring, and both male and female bears can be legally taken, though some provinces prohibit the hunting of females with cubs, or yearling specimens.^[23]

Currently, 28 of the USA's states have black bear hunting seasons. Nineteen states require a bear hunting license, with some also requiring a big game license. In eight states, only a big game license is required to hunt black bears. Overall over 481,500 black bear hunting licences are sold per year. The hunting methods and seasons vary greatly according to state, with some bear hunting seasons including fall only, spring and fall, or year-round. New Jersey, in November 2010, approved of a six-day bear-hunting season in early December 2010 to slow the growth of the black bear population. Bear-hunting had been banned in New Jersey for five years.^[115] A Fairleigh Dickinson University PublicMind poll found that 53% of New Jersey voters approved of the new season if scientists concluded black bears were leaving their usual habitats and destroying private property.^[116] Men, older voters, and those living in rural areas were more likely to approve of a bear-hunting season in New Jersey than women, younger voters, and those living in more developed parts of the state.^[116] In the western states, where there are large black populations, there are spring and year-round seasons. Approximately 18,000 black bears were killed annually in the USA between 1988–1992. Within this period, annual kills ranged from six bears in South Carolina to 2,232 in Maine.^[23]

Black bear meat

Nutritional value per 100 g (3.5 oz)
Energy	649 kJ (155 kcal)
Carbohydrates	0.00 g
Fat	8.30 g
Protein	20.10 g
Vitamins
Vitamin A equiv.	(10%) 78 μg
Thiamine (B1)	(14%) 0.160 mg
Riboflavin (B2)	(57%) 0.680 mg
Niacin (B3)	(21%) 3.200 mg
Minerals
Iron	(55%) 7.20 mg
Phosphorus	(23%) 162 mg
Other constituents
Water	71.20 g
Units μg = micrograms • mg = milligrams IU = International units
Percentages are roughly approximated using US recommendations for adults. Source: USDA Nutrient Database

According to Dwight Schuh in his Bowhunter's Encyclopedia, black bears are the third most popular quarry of bowhunters, behind deer and elk.^[117]

Meat

Black bear meat had historically been held in high esteem among North America's indigenous people and colonists.^[46] Black bears were the only bear species the Kutchin hunted for their meat, though this constituted only a small part of their diet.^[112] According to the second volume of Frank Forester's field sports of the United States, and British provinces, of North America:

The flesh of the [black] bear is savoury, but rather luscious, and tastes not unlike pork. It was once so common an article of food in New-York as to have given the name of Bear Market to one of the principal markets of the city.

— Frank Forester's field sports of the United States, and British provinces, of North America p. 186

Theodore Roosevelt himself likened the flesh of young black bears to that of pork, and not as coarse or flavourless as the meat of grizzlies.^[118] The most favoured cuts of the black bear's meat are concentrated in the legs and loins. Meat from the neck, front legs and shoulders is usually ground into minced meat or used for stews and casseroles. Keeping the fat tends to give the meat a strong flavour. As black bears can have trichinellosis, cooking temperatures need to be high in order to kill the parasites.^[119]

Black bear fat was once valued as a cosmetic article that promoted hair growth and gloss. The fat most favoured for this purpose was the hard white fat found in the body's interior. As only a small portion of this fat could be harvested for this purpose, the oil was often mixed with large quantities of hog lard.^[46] However animal rights activism over the last decade has slowed the harvest of these animals; therefore the lard from black bear has not been used in recent years for the purpose of cosmetics.

See also

• List of fatal bear attacks in North America

References

Bibliography

• Brown, Gary (1993). The great bear almanac. Lyons & Burford. ISBN 978-1-55821-210-7. 

Further reading

• Craighead, Lance (2000). Bears of the World. Voyageur Press. pp. 63–80. ISBN 0-89658-503-4. 
• Powell, Roger A (1997). Ecology and behaviour of North American black bears : home ranges, habitat, and social organization. Chapman & Hall,. ISBN 0-412-57990-1. 

External links

Wikimedia Commons has media related to Ursus americanus.

• Data related to Ursus americanus - (American black bear) at Wikispecies
• Wildlifeinformation.org: American Black Bear Conservation Action Plan
• Smithsonian Institution—North American Mammals: Ursus americanus (American black bear)