American Black Bear: Livestock and crop predation

Livestock depredations by black bears occur mostly in spring. A limitation of food sources in early spring and wild berry and nut crop failures during summer months are probably major contributing factors. 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. Though black bears will attack adult cattle and horses, they seem to prefer 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 being 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.

American Black Bear Fur: Attacks on humans

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. However, according to Stephen Herrero in his Bear Attacks: Their Causes and Avoidance, 23 people were killed by black bears from 1900 to 1980. The number of black bear attacks on humans is higher than those of brown bears, though this is largely because the black species outnumbers the brown rather than them being more aggressive. Compared to brown bear attacks, violent 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. The worst recorded fatality incident occurred in May 1978, in which a black bear killed three teenagers while fishing in Algonquin Park in Canada. The majority of attacks happened in national parks, usually near campgrounds, where the bears had become habituated to human contact and food. 1,028 incidences of black bears acting aggressively toward people, 107 of which resulted in injury, were recorded from 1964 to 1976 in the Great Smokey Mountains National Park, and occurred mainly in tourist hotspots where people regularly fed the bears handouts.

American Black Bear: Current range and population

Historically, black bears occupied the majority of North America's forested regions. Today, they are primarily limited to sparsely settled, forested areas.

Black bears currently inhabit much of their original Canadian range, though they do not occur in the southern farmlands of Alberta, Saskatchewan, and Manitoba. They have been extinct in Prince Edward Island since 1937. The total Canadian black bear population is 327,200 to 341,200, based on surveys taken in the early 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.

The current range of black bears in the United States is constant throughout most of the northeast, the northern mid-west, the Rocky mountain region, the west coast and Alaska. 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. Surveys taken from 35 states in the early 1990s indicate that black bears are either stable or increasing, excepting Idaho and New Mexico. The overall population of black bears in the United States has been estimated to range between 186,881 and 206,751, though this excludes populations from Alaska, Idaho, South Dakota, Texas, and Wyoming, whose population sizes are unknown.
As of 1993, known Mexican black bear populations exist 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 classed as endangered.

American Black Bear: Dietary habits

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. Young shoots from trees and bushes during the spring period are 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 this period, they may also raid the nut caches of squirrels. Black bears are 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.

The majority of the black bears animal diet consists of insects such as bees, yellow-jackets, ants and their larvae. Black bears 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. They will prey on mule and white-tailed deer fawns in certain areas. In addition they have been recorded preying on elk calves in Idaho and moose calves in Alaska. Black bears rarely attack adult deer, which are too swift, but have been recorded killing adult deer confined in wooden traps. They may hunt adult moose by ambushing them as they pass by. Black bears often drag their prey to cover, preferring to feed in seclusion and frequently begin feeding on the udder of lactating females, but generally prefer meat from the viscera. 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 may climb up to bald eagle nests to eat the eggs or chicks. Black bears have been reported stealing deer and other animals from human hunters.

Ameriacan Black bear: Winter dermancy

Black Bears are not true hibernators, but they do become significantly less active and go into a dormant state during the winter months. This is sometimes referred to Seasonal Lethargy. Black bears enter their dens in October and November. Prior to that time, they can put on up to 30 pounds of body fat to get them through the seven months during which they fast. Winter dormancy in Black Bears typically lasts 3–5 months. During this time, their heart rate drops from 40 - 50 beats per minute to 8 beats per minute. They spend their time in hollowed-out dens in tree cavities, under logs or rocks, in banks, caves, or culverts, and in shallow depressions. Females, however, have been shown to be pickier in their choice of dens, in comparison to males. A special hormone, Leptin is released into their systems, to suppress appetite. Because they do not urinate or defecate during dormancy, the nitrogen waste from the Bear's body is biochemically recycled back into their proteins. This also serves the purpose of preventing muscle loss, as the process uses the waste products to build muscle during the long periods of inactivity. While they do not eat, drink, defecate, or urinate at this time. In comparison to true hibernators, their body temperature does not drop significantly (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. During winter, black bears consume 25–40% of their body weight. The footpads peel off while they sleep, making room for new tissue. After emerging from their winter dens in spring, they wander their territories for two weeks so that their metabolism accustoms itself to the activity. They will seek carrion 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.

Ameriacn Black Bear Reproduction

Sows usually produce their first litter at the age of 3–5 years. Sows living in urban 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. Sows tend to be short tempered with their mates after copulating. The gestation period lasts 235 days, and litters are usually born in late January to early February. Litters usually consist of 2 cubs, though litters of 6 have been recorded. At birth, cubs weigh 10–16 ounces, and measure 8 inches 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. At the age of six weeks, they attain 2 lb, by 8 weeks they reach 5 lb and by the age of 6 months they weigh 40–60 lb. They reach sexual maturity at the age of three years, and attain their full growth at 5 years.
The average lifespan in the wild is 18 years. The record age of a wild specimen was 31 years, while that in captivity was 44 years.

American Black Bear Fur

The fur is soft, with dense underfur and long, coarse, thick guard hairs. Their fur is not as shaggy and rough as the 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 the name of black bears show great variation of colors. Individual coat colors can range from 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. 70% of all black bears are black, though only 50% of black bears in the Rocky Mountains are black.

American Black Bear Size

American black bears vary in size depending on sex, food availability and quality, and other factors. Male black bears may grow 20 to 60 percent larger than females. Weight of black bears vary with age, sex, season and health. 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 than the black beas from the West coast. Adult males usually weight between 125 and 550 lb, while females weigh 33% less at 90–275 lb. The largest subspecies on average is U. americanus carlottae of the Queen Charlotte Islands and Alaska. The biggest wild American Black Bear ever recorded was a male from North Carolina, shot in 1998, that weighed 400 kg (880 lb). Adults are 4–6 ft in length, and 2.5–3 ft in shoulder height.[32] 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 950–1,000 lb (430–450 kg) in the fall of 2006. , the female, weighed 555.5 lb (252.0 kg) in the fall of 2007.

American Black Bear Build

American black bear skull is wide, with narrow muzzles and large jaw hinges. Females tend to have more slender and pointed faces than males. Their claws are typically black or grayish brown. Claws are short and rounded, being thick at the base and tapering to a point. Claws from both hands and legs are the same length, , though the foreclaws tend to be more sharply curved. Their hind legs are longer than the Asian black bear hind legs. The tail is usually 4.8 inches (12 cm) long. The ears are small and rounded, and are set well back on the head. The soles of the feet are black or brownish, and are naked, leathery and deeply wrinkled. Black bears are highly dexterous, being capable of opening screw-top jars and manipulating door latches. They also have great physical strength, having been known to turn over flat-shaped rocks weighing 310 to 325 pounds (140 to 147 kg) by flipping them over with a single foreleg.[32] They move in a graceful, rhythmic and surefooted way and can run at speeds of 25–30 mph (40–50 km/h).[33] 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.

American Black Bear Hybrids

American black bears are reproductive compatible with several other species of bears, and have often produce hybrid offspring. According to Jack Hanna's Monkeys on the Interstate, a bear captured in Sanford, Florida thought to be a offspring of escaped female Asian black bear and American black bear. In 1859, a black bear and a Eurasian brown bear were bred together in the London Zoological Gardens, but the three cubs did not reach maturity. In The Variation of Animals and Plants under Domestication Charles Darwin noted:

In the ninth-year report has found that the bears are 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).

A huge black bear was shot in Autumn 1986 in Michigan, for which some thought was a hybrid of black bear and grizzly bear, due to its unusually large size and its proportionately larger braincase and skull. DNA tests failed to show whether it is a black bear or grizzly bear.

American Black Bear Subspecies

Sub-Species Name	Common Name	Distribution	Description
Ursus americanus altifrontalis		Found in the Pacific Northwest coast from central British Columbia through northern California and inland to the tip of northern Idaho and British Columbia
Ursus americanus amblyceps		Native to Colorado, New Mexico, west Texas, the eastern half of Arizona into northern Mexico; southeastern Utah
Ursus americanus americanus		Found in eastern Montana to the Atlantic coast; from Alaska south and east through Canada to the Atlantic and south to Texas. Thought to be increasing in some regions.
Ursus americanus californiensis		Found in the mountain ranges of Southern California, north through the Central Valley to southern Oregon
Ursus americanus carlottae	Haida Gwaii Black Bear	Haida Gwaii/Queen Charlotte Islands and Alaska	Generally larger than its mainland counterparts with a huge skull and molars, and is only found as a black color phase
Ursus americanus cinnamomum	Cinnamon Bear	Idaho, western Montana, and Wyoming, eastern Washington and Oregon, northeastern Utah	Has brown or red-brown fur, reminiscent of cinnamon.
Ursus americanus emmonsii		southeastern Alaska. Stable.	Distinguished by the fur of its flanks being silvery gray with a blue lustre
Ursus americanus eremicus		northeastern Mexico. Endangered.
Ursus americanus floridanus	Florida Black Bear	Florida, southern Georgia, and Alabama. Threatened in Florida as the Florida Black Bear (state list).	Has a light brown nose, and shiny black fur. A white chest patch is also common. An average male weighs 299 pounds (136 kg)
Ursus americanus hamiltoni	Newfoundland Black Bear	Newfoundland	Generally bigger than its mainland relatives, ranging in size from 90 to 270 kg and averaging 135 kg. It also has one of the longest hibernation periods of any bear in North America
Ursus americanus kermodei	Kermode Bear, Spirit Bear	Central coast of British Columbia	Has white fur due to a rare genetic trait
Ursus americanus luteolus	Louisiana Black Bear	Eastern Texas, Louisiana, southern Mississippi. Threatened (federal list).	A subspecies with a relatively long, narrow, and flat skull, and proportionately large molar teeth
Ursus americanus machetes		North-central Mexico
Ursus americanus perniger		Kenai Peninsula, Alaska
Ursus americanus pugnax		Alexander Archipelago, Alaska
Ursus americanus vancouveri		Vancouver Island, British Columbia

Taxonomy and evolution

Although they all live in North America, American black bears, brown bears, and polar bears are not closely related, genetic studies have revealed that they split from a common ancestor before about 5,05 million years. Both American and Asiatic black bears are considered sister taxa, and are more related to each other than other bears species.

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

Ancestor of the American black bear and the Asian black bear diverged from sun bears 4.58 million years ago. Then the American black bear separated from the Asian before about 4.08 million years ago. The earliest fossils of American black bears, which are located in Port Kennedy, Pennsylvania, greatly resemble the Asiatic species, though later specimens grew to sizes comparable to grizzlies. From the Holocene to present, American black bears seem to have shrunk in size, but this was rejected due to issues of aging of the fossil samples.

American black bear lived in the same period as 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 millions years ago. The short-faced bears are thought to have been heavily carnivorous and the FL spectacled bear more herbivorous, 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 3 genera, is the only survived climatic and vegetative changes during and after the Ice Age, while others more specialized North American predators extinct. However, both Arctodus and Tremarctos had survived several other ice ages. After these prehistoric Ursids went extinct during the last glacial period 10,000 years ago, black bears are probably the only bears in much of North America, while brown bears did not come into the rest of continent.