AMERICAN BLACK BEAR

American Black Bear_U americanus Minnesota_D Garshelis

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This species is by far the most common bear in the world, although it occupies just 3 countries. Commonly called “the black bear” in North America, the true name is the American black bear, to distinguish it from the Asiatic black bear. These two similar-sized species are ecologically alike. They are believed to be “sister species”, originating from a common ancestor that crossed from Asia to North America.

Unlike the Asiatic black bear, the American black bear has robust expanding populations, because human-caused mortality is more controlled: government agencies that manage legal hunting also have been effective at controlling poaching and human–bear conflicts. As populations of this species have grown numerically and expanded geographically, conflicts between bears and people have increased, but there has also been increasing public awareness and appreciation of this species, especially in areas of their range where there are no grizzly bears (which garner more public attention than black bears).
The prime attributes of this species explaining its burgeoning populations is its ability to use a variety of habitats, exploit many types of food, and live near people.

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Except where noted, all photos on this page are wild bears and natural environments, taken by field biologists.

TAXONOMY & CHARACTERISTICS

Ursus americanus

  • Straight facial profile
  • Black or various shades of brown; white and grey phases in some areas
  • White chest marking variable size and shape; often not present
  • Excellent tree climber
  • Generally unaggressive towards people

Ursus americanus [Pallas, 1780]: Once placed in the monospecific genus Eurarctos. Sixteen subspecies have been named based on morphology and geographic isolation. Some of these gained special legal protections, particularly in southeastern U.S. However, recent genetics work suggests that the number of subspecies may be too high, and some may be too ill-defined to be considered subspecies.

Distinctive characteristics:This is a medium-sized bear with a straight profile from forehead to nose, and no hump on its shoulders (distinguishing it from the grizzly bear). Claws are short and curved on both front and hind feet, well suited for climbing (also unlike the grizzly bear). Ears are not as large as the Asiatic black bear, but may appear especially large in young bears, with smaller heads. Although commonly known as the American black bear, coat color (even within a single litter) ranges from black to various shades of brown (including a reddish-orange color called cinnamon) to blonde. Black-colored bears predominate in the eastern and northern parts of the range, whereas the proportion of brown-colored individuals is higher in western states, possibly associated with temperature regulation in more open habitats. Brown-colored black bears are common in California, Arizona, New Mexico, and parts of the Rocky Mountains. A rare white (non-albino) color phase, associated with a single recessive gene, occurs in coastal British Columbia (called the Kermode bear or spirit bear). A very rare “blue” (grey) color phase known as the glacier bear occurs in northwestern British Columbia and along the southeast coast of Alaska (and occasionally interior Alaska). American black bears sometimes have a white chest marking, although the size and shape varies among individuals rather than being distinctively shaped across the species (unlike the distinctive crescent-shaped marking in Asiatic black bears and sloth bears). The occurrence of a chest blaze varies among populations. Cubs are often born with a white chest marking, which may disappear after molting during their first year of life.

Distinctive behaviors: American black bears are typically unaggressive toward people, and often can habituate to human activity and benefit from consuming human-related foods. They are more tolerant of people than other species of bears. They may use small woodlots near homes, and even den near roads, railroad tracks, or houses. When in human-populated areas, they may shift to more nocturnal activity to reduce contact with people. Nevertheless, a few black bear attacks on people occur annually across their range, some of which are fatal. Attacks are sometimes instigated by the bear chasing an off-leash pet dog. It is a myth, though, that these bears become aggressive if a person just happens to walk between a mother and her cubs. Often cubs will climb a tree if they perceive danger, and remain until called down with a distinctive guttural sound by the mother. Mothers may wander and forage sizable distances (and for several hours) from a tree where her cubs have taken refuge. All sex and ages are ready tree climbers.

RANGE COUNTRIES

Distribution: This species occurs in only 3 countries: Canada, United Sates, and Mexico. Among the bears, only the giant panda is found in a fewer number of countries. There is no evidence of black bears ever occurring in southern Mexico or Central America. Today resident populations range southward to 23°14´ N, and northward to 69°29´ N (from subtropics to subarctic). Historically their range northward has been limited by lack of berry-producing plants. Factors limiting the southward extent of the range are unclear, as historically there was ample forest, including oak trees. Vagrant bears have recently been observed farther north and also farther south (21°). The northward expansion is related to the warming climate, and the southward expansion to a burgeoning population in northern Mexico and forest protection efforts south of there.

They occur along the coastlines of the Atlantic Ocean, Gulf of Mexico, Pacific Ocean, and Gulf of Alaska, but not the treeless coastal areas adjacent to the Bering Sea or Arctic Ocean. They also occur on many islands off the coasts of Alaska and British Columbia (including large populations on Vancouver Island and Haida Gwaii archipelago), and on the East coast are found on Newfoundland (but were extirpated from Prince Edward Island and Anticosti Island, Quebec).

American-black-bear_U-americanus_range-map-Bear-Specialist-Group_B-Scheick



Range countries, states and provinces:

Canada:

  • Resident (12 provinces and territories): Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland & Labrador, Northwest Territories, Nova Scotia, Nunavut, Ontario, Quebec, Saskatchewan, Yukon
  • Extirpated: Prince Edward Island (1927)

United States:

  • Resident (41 states): Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Florida, Georgia, Idaho, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, Wyoming
  • Vagrant (8): Delaware, Indiana, Illinois, Iowa, Kansas, Nebraska, North Dakota, South Dakota
  • Never occupied: Hawaii

México:

  • Resident (6 states): Chihuahua, Coahuila, Durango, Nuevo Leon, Sonora, Tamaulipas
  • Vagrant (5 states): Aguascalientes, Hidalgo, Jalisco, Querétaro, San Luis Potosi, Zacatecas
  • Extirpated: Nayarit, Sinaloa

Extirpation: Not extirpated in any historic range country. In Canada, the only provincial extirpation was Prince Edward Island (last individual killed in 1927). Previously extirpated from several U.S. states, some of which were recently recolonized (Kentucky, Missouri, Nevada, Ohio, Oklahoma, Rhode Island, Texas), naturally or with human assistance, from neighboring states. Other extirpated states have reported occurrence of a few vagrant bears, but no established population yet. Extirpated in some southern México states, but the southern historic limit is ill-defined.

Elevational range: Near sea level to 3500 m, but typically not above treeline.

Overlap with other bear species: American black bears overlap and compete with grizzly (brown) bears in the western part of their range. However, coastal Pacific islands are inhabited by one species or the other, possibly indicating that they can exclude each other, depending on the circumstances. American black bears have long overlapped with polar bears in coastal areas of James Bay and Hudson Bay in Ontario, Manitoba and Québec. With climate change, there are reports of American black bears extending their range farther north (near Hudson Strait in northern Québec, and southeastern Nunavut near the Hudson Bay coast). Recent records of some grizzly bears in northern Manitoba indicate that all three North American bears overlap there.

ECOLOGY

  • Mainly a forest-dweller, but also lives in some treeless areas
  • Omnivorous diet of green vegetation, insects, fruits and nuts
  • Hibernates across the range, but some winter-active animals in warmer regions with available food
  • Breed in summer, give birth in winter; raise cubs for 1.5 years

Habitat: Primarily a species of temperate (deciduous) and boreal (coniferous) forests, but they also inhabit other diverse habitats such as dry scrub forests of Mexico, bottomland hardwood swamps in the coastal plain of the southeastern U.S., temperate rainforests of Alaska and British Columbia, and treeless Labrador tundra (where they occupy the typical niche of the grizzly bear). In northern México and south Texas they use and cross wide expanses of desert habitats and feed on succulents. At the other extreme, some bears reside in suburban or urban environments. Many studies have relied on radio-collared bears (now with GPS units) to understand habitat use, and how this relates to their growth rates, reproductive rates, and mortality rates.

Diet: A generalist, opportunist omnivore whose diet varies by location and season. Their diet is mostly plant-based, including herbaceous vegetation, roots, buds, succulents such as yucca and cactus fruits, and numerous kinds of shrub or tree-borne fleshy fruits and nuts, as they become ripe. They climb trees to eat buds and nuts such as beechnuts and acorns; while feeding they may break branches toward the trunk, forming a nest on which they sit and rest (similar to Asiatic black bears). However, most feeding is from the ground (fruits on bushes and nuts fallen from trees).

Animal foods include insects (especially ants) in life stages from egg to adult, and vertebrates from fish to mammals. They may kill deer fawns and moose calves shortly after birth, but very rarely kill adult ungulates. When available, they may consume various human-related foods, from garbage and birdseed to a variety of agricultural products, including corn, oats, soybeans, sunflowers, wheat, apples and other tree-borne cultivated fruits, and brood and (to a lesser extent) honey in apiaries. In some localized areas they prey on calves of cattle, especially when cattle are concentrated near watering areas.

Black bears may migrate elevationally, corresponding with ripening of different foods. In non-mountainous areas, during late summer and fall, they may migrate considerable distances (100–200 km) to find more abundant food sources in preparation for hibernation.

Hiberbation:Hibernate for up to 7 months in the northern portions of their range, but for considerably shorter periods in more southerly areas. In fall, they eat profusely in preparation for the winter, packing on as much fat as possible. Their body temperature drops only a few degrees (from 37°C in summer to 32–34°C in winter). Allowing them to be semi-alert to dangers; nevertheless, they are considered unique true hibernators in that they do not eat or drink, typically do not urinate or defecate, and lose very little bone or muscle mass despite being sedentary all winter. Their heart rate slows from 80–100 per minute in summer to about 10–30 per minute in winter. During hibernation their heart pumps a few beats synchronized with their 2–5 breaths per minute, then stops between breaths. In some southern and low-elevation areas, where food is available year-round, some bears may remain active during winter. However, all pregnant females den to give birth to cubs.

These bears use a wide variety of den structures, depending on location, including natural caves, ground-level or above-ground cavities in hollow trees, underground chambers that they excavate, root masses, brush piles, or even above-ground nests. Even in the coldest environments, some bears den in an open nest, where snow accumulates on their back due to the insulation of their hair and thick layer of fat, and reduced blood flow. Some dens are in remote areas, while others are near human dwellings, even under porches.

Researchers commonly visit dens of radio-collared bears, to study den selection, hibernation physiology, growth rates, reproduction, and to refit or change radio-collars. While hibernating, these bears are relatively easy to drug and temporarily extract to conduct such studies.

Reproductive Cycle: Mating typically occurs in May–July, but this period may be extended in southern latitudes. Females breed with multiple males, and males mate with multiple females so littermates could have different fathers, and males may father more than one litter in a year. Implantation of the fertilized egg is delayed until November or early December, and active gestation is only 2 months. Birthing occurs in January or early February while the female is hibernating; she nurses her cubs during hibernation, while consuming no food or water. Females generally produce their first litter at 3–6 years old (though this can be as late as 10 in northern populations), and every other year thereafter. In places with less food, or if there is a widespread seasonal food failure, the interval between litters may extend to 3 years (i.e., females must attain sufficient body mass by fall for successful implantation and development of embryos). Cubs stay with their mother for 16–17 months, denning with their mother as yearlings (1-year-olds); in rare cases they stay an extra year. Average litter size is ~2.5 cubs in the eastern and midwestern portions of the range (ranging up to 5 or rarely 6 cubs [females have 6 nipples]) versus 2 cubs (averaging less in some areas) in western and northern parts of the range. Reproductive rate in this species is highest among the bears. They can produce cubs until their mid-20s, and can live to their late 30s in the wild (the oldest known was 39 years). If a female lived to reproductive senescence, she could produce 30 or more cubs in her lifetime. Cub sex ratio at birth is 50:50, or slightly male-biased.

POPULATIONS

  • Main source of mortality is legal sport hunting
  • Mark–recapture population estimates conducted in various ways to monitor population trends
  • Population densities vary 100-fold, depending on food conditions
  • Populations increasing and expanding in most areas

Causes of Mortality: Accurate information on causes of death have been obtained from radio-collared bears. The most common cause of mortality for this species is legal sport hunting (except where it is not hunted). Other human-caused mortality includes killing of bears that cause property damage or are perceived as a threat to people, and being hit by vehicles. Natural mortality includes some intraspecific killing (bears killing bears). This was witnessed to a relatively high extent in an arid environment during a drought when bears concentrated around small patches of food and water. Disease is rare, and starvation-related mortality is also rare, but may occur in cubs, yearlings, and sometimes 2-year-olds especially during or following natural food failures.

Population estimation methods: Because these bears are difficult to see in most environments, estimates of population size or density are typically derived using mark–recapture approaches. Marking can take the form of eartags, radiocollars, an ingested biomarker, or a DNA sample; recapture may involve physical capture in traps, a sample of hunted animals, or hair samples collected on barbed wire snags. Population estimates have been produced for defined study sites as well as entire states or provinces. Jurisdiction-wide population monitoring is also conducted from population reconstruction or modelling using ages obtained from growth rings in teeth of legally-hunted bears. In most hunted populations, management agencies collect a bear tooth from hunters to assess the age structure.

American black bear release from a Minnesota barrel trap – S Rettler

Local population estimates: Empirically-derived population estimates have been obtained in more than 60 sites across the range of this species; half of these fell in the range of 15–40 black bears per 100 km2 (or about 40–100 bears per 100 mi2). Large differences in density occur as a result of how much food is available in the habitat (which drives reproduction), and also the extent of human-caused mortality. Very low density populations (1.5–5 bears/100 km2 = 4–13/100 mi2) have been reported in marginal habitats in Colorado (high elevation), Florida, South Carolina, and Alaska. At the opposite extreme are populations that are 100x more dense: >1.5 bears per km2 (4/mi2)(excluding cubs) on a coastal Alaskan island with abundant natural foods, including berries and salmon, and >2 bears per km2 (5.5/mi2) in coastal North Carolina where bears had access to abundant agricultural crops.

Country and global population estimate: Many state and provincial population estimates are not rigorously derived, but rather a best guess from management agencies. Summing these, the total U.S. population, excluding Alaska, is estimated at >300,000. Estimates for Alaska range widely, from 100,000–200,000. Estimates for Canada center around 450,000 (principally in British Columbia, Ontario, Manitoba, and Québec). No population estimates exist for México. The total for North America is likely 850,000–950,000, which is more than twice that of all 7 other bear species combined.

Population trends: Most U.S. states report populations that are increasing numerically and geographically, Canadian provinces report increasing or stable populations, and populations in México vary significantly by region, but are generally thought to be increasing.

THREATS

Red List Status: LEAST CONCERN

Red List Threat Banner

  • Not threatened, either globally or regionally
  • Most common bear species
  • Populations managed through legal hunting in most areas

Least Concern –– This species occupies a large portion of its historical range (65–75%), and populations are generally increasing or stable, because human-caused mortality is below the reproductive rate.

Threats: American black bears are not threatened. They are harvested as a game species in all 12 Canadian provinces and territories where they exist and in 32 U.S. states, including 5 states where hunting was previously closed or not allowed (New Jersey, Maryland, Kentucky, Oklahoma, and Nevada). The sport harvest for this species in Canada and the U.S., totaling 40,000–50,000 annually, is controlled by state and provincial agencies to fit management objectives. They are not legally hunted in México, but some conditional permits are allowed for depredation cases. In some areas, the biggest concern is increasing conflicts with people. Bears may be killed to protect property or crops.

RESEARCH & CONSERVATION

  • One of the most well-studied bears (and among most well-studied Carnivores)
  • A true conservation success story
  • Species is well adapted to living near humans

Research: Extensive research has been conducted on this species to gain information about population size, factors affecting mortality and reproduction, habitat use and selection, foraging habits, seasonal movements, interactions with people, den ecology and hibernation physiology, seasonal changes in weight and body condition, and many other aspects of their biology and ecology. Much of this information has been gained through capture and handling, and radio-collaring (now mainly with GPS collars that transmit data back to researchers via a satellite).

Conservation measures: Through the 1800s and early 1900s, black bears lost extensive habitat due to clearing of forests. At the same time, they were widely hunted for meat, skins, and fat, or hunted or poisoned with the intent of eliminating or severely reducing their numbers to lessen damage to crops, apiaries, and livestock. Governments often paid a bounty to encourage the killing of black bears.

Protection and recovery occurred state-by-state and province-by-province during 1902–1983 as laws were changed and bears gained protection as a big game species. In southeastern U.S., a system of sanctuaries (centered around national parks) was established where bears were not hunted, providing a nucleus for future expansion.

Increased forest habitat and reduced human-caused mortality led to rapid recovery since the 1980s. States and provinces controlled legal hunting (through restrictions on hunting seasons, bag limits, and license quotas). More research and better population monitoring methods in recent years enabled agencies to adapt management policies to allow populations to grow, commensurate with a more favorable opinion of this species by the public.

Wildlife management agencies also have taken an increasingly active role in reducing the number of bears killed in conflict situations with people, in some cases involving stricter laws against shooting and intentional or inadvertent feeding (in some jurisdictions, feeding bears is illegal and bear-resistant trash receptacles are required). Educational programs aimed at reducing availability of food and garbage that could attract bears, promoting public tolerance, and recognizing that black bears are typically not a threat to human safety, have all contributed to increased social acceptance of black bears living near people. The relatively docile nature of this bear, and its ready habituation to people has fostered greater coexistence between American black bears and humans than for any other bear.

In all, the conservation of this bear species is one of the most successful of any carnivore worldwide.