Bear Species
American Black Bear
(Ursus americanus)

American black bear (Ursus americanus)  © Diane Ronayne
© Diane Ronayne

Physical description and lifespan

This medium-sized bear averages approximately 1.9 metres (m) in length. Adult males weigh 60–140 kilograms (kg), rising occasionally to 300 kg in the most productive habitats; adult females typically weigh less, averaging 40–70 kg.

As the name suggests, this species has predominately black fur, although this can vary from light blond to dark brown in more arid habitats. Two unique colourations – white and blue – are found in the Pacific Northwest. American black bears often have a white blaze on the chest and a light brown muzzle.

The lips of American black bears, like most bear species, are free from the gums and protrusible – can be thrust outwards – enabling them to pick up small food items. They have short, tightly curved claws that cannot be retracted. American black bears have five toes on each foot and are ‘plantigrade’ (walk on the soles of their feet).

The lifespan on an American black bear is typically less than 25 years, although individuals – usually females – may reach 35 years. Adult females are thought to have a survival rate of 80–90 per cent in areas where they are not hunted or lightly hunted. In heavily hunted populations mortality is higher for males than females.

Distribution

The American black bear is still found to across much of its historical range in North America, occupying a range of habitats from arid desert environments to rainforest areas in the Pacific Northwest, and from sea level to over 2,500 metres above sea level (masl).

As their varied distribution shows, American black bears are quite adaptable and can thrive alongside humans if protected from illegal hunting and killings. Their distribution appears to be increasing in some areas, notably the north-eastern U.S. and in Texas, where they were nearly destroyed during colonisation.

Little is known about the distribution of American black bears in Mexico, but recent studies suggest that at least four areas in the northern part of their historic Mexican range still have viable populations (meaning they are not at risk of local extirpation). However, a lack of enforcement of laws preventing the shooting of bears on public lands remains a significant threat to American black bear populations in Mexico.

Behaviour

Adult American black bears are shy and only occasionally observed in groups around concentrated food sources. Adults are normally solitary with the exceptions of females and their young and consort pairs during breeding season.

Although not a territorial species, American black bears do maintain well-defined home ranges. The adult female’s preference for spatial separation is likely to be due to a social system based on dominance hierarchy.

American black bears are crepuscular – active at dawn and twilight – for most of the year, but breeding and feeding activities and disturbance can alter these patterns, seasonally and locally.

Reproduction

The age of sexual maturity for American black bears varies with habitat quality. In areas where food resources are abundant, females may produce their first cubs at two years of age (although three years is more common); in poor quality habitats, females may not have their first litter until four to eight years of age.

The mating season can last from late April through to August, with a peak in breeding activity in June and July. Estrus – the period during which females are willing to mate – usually lasts less than five days and ovulation appears to be induced by mating.

Although the total length of gestation may be 6.5–8.5 months, active gestation lasts for approximately 60–70 days. Females give birth in late December to early February, while still in the winter den.

Litter size can range from one to five cubs, with two or three being typical. The average litter size is usually larger in areas with good quality habitats – those with food, water, sites for dens and good cover provided by foliage – and where the mean age of females is greater. In good food years the interval between litters is two years, but can be more than three years in poor quality habitats, during severe droughts, if a female keeps her young an extra year or has a fallow year between litters.

Diet

American black bears are omnivorous; up to 90 per cent of their diet is formed of plant material, primarily grasses and forbs (herbaceous flowering plants) in spring and mast crops during summer and autumn. They are particularly dependent on hard and soft mast crops for survival during winter hibernation.

This diet is supplemented with insects and a small quantity of meat from scavenging or killing small mammals and infant ungulates (hoofed mammals) such as deer, elk and moose. 

Conflict with humans

The American black bear’s willingness to co-exist with people has led to Human Bear Conflict across their range, including: incidents associated with crop raiding (primarily cereal grains and corn), attacks on livestock (largely domestic sheep, but also cattle, poultry and goats), damage to private and commercial bee hives, competition with man for ungulates such as deer and nuisance activities in search of accessible human-produced foods (for example, bin raiding).

Management authorities in North America continue to use both lethal and non-lethal methods to resolve Human Bear Conflict; researchers and bear managers in North America have developed a number of useful methods for reducing or eliminating damages. Many community-based programs for conflicts reduction in and adjacent to small towns located in bear habitat are based on the BearSmart criteria developed in Canada during the 1990s. 

Read more about BearSmart criteria >>       

2010 conservation status

The American black bear is not listed as an endangered species on the International Union for Conservation of Nature (IUCN) 2010 Red List; populations are generally considered to be stable or increasing across most of its range. However, an increasing alteration to and loss of habitat poses a threat to this bear’s survival.

 

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