Author: Richard Plunkett
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|Scientific Name: Ursus americanus
Common Name: American Black Bear, Cinnamon Bear
Spanish Name: Oso Negro
Black bears are the most common bears in North America. Despite their name, they come in a variety of colors ranging from black to brown, cinnamon, and even blond. Most have shaggy black or dark brown hair with a lighter brown snout, and some may have have a white chest patch. They have small eyes, rounded ears and a straight or rounded long snout which is different from the concave or “dished” face of grizzlies. Black bears are medium sized; adults average 5 feet long with a short tail and are about 2 feet tall at the shoulder. They weigh from 220 to 330 pounds, although large males may occasionally reach 496 pounds!
Black bears can stand and walk on their hind legs, but they usually stand on all fours. They seem to shuffle because they have a flat-footed stride and their hind legs are slightly longer than the front. Their paws have curved claws that cannot be pulled back in (non-retractable claws), which are useful for digging and climbing. They may be large and strong, but they are also very quick and agile.
Black bears may live as long as 30 years, but in the wild they rarely live past age 10, mostly because of contact with humans.
Black bears are found throughout North America. Their range extends from Alaska to Eastern Canada to as far south as northern Mexico. The subSpecies U. a. amblyceps is found in the southwestern United States and northern Mexico. This subSpecies has been identified in Colorado, New Mexico, and the eastern half of Arizona. In the past they have been seen in west Texas, Oklahoma, and in southeastern Utah.
Black bears love homes that are very hard to get to, that are in thick understory vegetation, and have a large amount of food. This kind of habitat is found in vegetated mountainous regions between 2952 and 9842 feet in elevation, and consists mostly of pinyon-juniper woodland areas. Mixed forests which provide food (such as pinyon and oak) are good areas to find black bears. Although they usually need woodland cover, black bears can also be found in grassy or brushy areas, and in riparian areas (areas around water ways) as well. As more and more black bear habitat is used by humans, there is an increase in their association with humans.
Black bears eat a variety of foods, depending on what is available in different places and at different times of the year. Black bears depend primarily on plants for food, they change their diet with the seasons. In the spring they mainly eat grasses and herbs; in the fall they eat a combination of soft fruits and berries, and hard nuts (acorns); in the summer they eat fruits and berries from trees and shrubs (In the southwest, black bears may include fruits of prickly pear cactus); During the summer months when there is a lot of food, black bears are able to eat a lot of different kinds of food, and they store large amounts of fat in the fall, primarily from fruits, nuts and acorns, to prepare for winter hibernation. In the winter, when food is most scarce, black bears hibernate in dens. When they emerge in the spring and little food is available, they live partly off stored body fat from the previous fall—and they continue to lose weight until the summer when fruits and berries are available.
Black bears are not entirely herbivorous, because they do eat insects and beetles, and now and then will eat meat from dead animals they find. Black bears are not considered to be active predators. Rarely, black bears may kill livestock animals and can break into commercial beehives looking for honey. Where they come in contact with humans, black bears are found around garbage dumps and landfills, and human trash can be a major food source.
Black bears are sometimes preyed on by mountain lions (Felis concolor), and occasionally coyotes (Canis latrans) will take black bear cubs. They are also hunted by humans.
Reproduction and Development:
Black bears reach sexual maturity at 4 to 5 years of age. Mating season is generally in the late spring (May and June). Female black bears experience delayed implantation of the fertilized egg. This means that the embryo divides, but does not begin to fully develop until females enter their dens for hibernation in late fall, and only if the female has stored enough fat to sustain herself and a developing cub through the winter. Female black bears may give birth to 1 to 6 cubs (twins are most common) in January or February. Black bear cubs may be 1/250th the size of the mother bear, and are the smallest newborns, compared to their mothers, of any placental mammal. These tiny and blind cubs remain in the den with the mother and continue to grow and develop in what is described as an “external pregnancy” until it is time to leave the den in the spring. By this time cubs weigh 5 to ll pounds each.
New black bear cubs will stay with their mother through their first year. They are weaned by mid to late summer, but will return to the den to hibernate with the female for their first winter. During their first year black bear cubs are dependent on their mother to teach them all the food gathering and survival skills they will need as adult bears. They finally leave home at about 17 months to start their own lives. By age 3, young males will leave the den and travel maybe 124 miles to create their own territories. The mother will be ready to mate again and may have cubs every two years depending on how much food is available.
Black bears communicate through vocalizations, body language, and scent. Grunts are used to express sociability, moaning and huffing indicate fear, and anger is shown by a a deep and rhythmic voice. Black bears use screams and bellows to register pain, and they show pleasure with a motorlike hum. Both males and females use urine to mark their territories. Before and during the mating season, females and adult males rub and scent-mark “bear trees.”
Black bears are generally active at dawn and dusk and spend periods of inactivity in forest beds, which are usually shallow holes made in piles of dead leaves on the forest floor. This may change during mating season and also depends on how much food is available. Where human garbage or food is available, for instance near roadsides or in campgrounds, bears may become diurnal (active during the day) or nocturnal(active at night).
Black bears are normally animals that live alone. The exceptions to this are adult females who live with their cubs, breeding pairs of adult bears, and bears gathering at feeding sites. Large numbers of black bears may form social groups where food is found in a central location, including non-related animals of the same sex who travel and play together.
Black bears spend the winter hibernating in dens built in tree cavities, under logs or rocks, and in caves or culverts. In the spring when they come out from hibernation, black bears move to lower elevations and southerly slopes. They then move to higher elevations and easterly and northerly slopes as more food becomes available in the summer and fall.
Adult females establish territories if there is plenty of food that is well spread out. These territories average 4 square miles and are defended by the female and shared with her independent offspring. Males also establish territories, but these areas are larger (averaging 31 square miles) in order to include both food and possible mates. These larger territories are difficult to defend and often overlap the ranges of other males. Though they generally live alone, fighting occurs between males during the mating season. As they get older, male black bears may become large enough to dominate younger males without even fighting. A 10 year old male may be 2 to 3 times the size of a young male entering his territory and twice the size of a mature female.
The biggest threat to black bear populations is loss of habitat and humans moving into their territories. Not only are black bears losing their older ranges, encounters with humans are increasing around housing developments, garbage dumps and roadways. Black bears suffer from a bad image as ferocious, mean-spirited and aggressive. This has led to high numbers of black bears being shot—more than 90 percent of the deaths of black bears older than 18 months are from gunshots, trapping, motor vehicle accidents or other human activity.
Black bears have been protected by law since 1927, but are listed as game animals in New Mexico and are hunted during open season, mostly for pelts and as trophies. Black bears are listed as endangered in Texas and in Mexico. The black bear population of New Mexico decreased from an estimated 3,000 in 1967 to around 1700-1800 in 1988. Though this number was considered stable, the number of pelts tagged in New Mexico jumped from an average of 290 per year (1978-1992) to 482 per year in 1993 and 1994. The low numbers of offspring and the fact that it takes them a long time to reach sexual maturity leave black bears vulnerable to overharvesting. This is because they cannot reproduce fast enough to replace the bears that are being killed (harvested for their pelts).
Species information was obtained from the Biota Information System of New Mexico (BISON) and the following sources:
The Smithsonian book of North American Mammals . D.E. Wilson and S. Ruff (eds.). The Smithsonian Institution, 1999.
Mammals of North America. E.R. Hall and K. R. Kelson. The Ronald Press Company, 1959.
Related Terms: ursus americanus, american black bear, cinnamon bear, oso negro