AMERICAN BLACK BEAR: CHARACTERISTICS, HABITAT, FEEDING - BIOLOGY

The American black bear (Ursus americanus) is a species of placental mammal belonging to the Ursidae family that lives in Canada, the United States and Mexico. It has a robust body and a short tail.

Depending on the availability of the food and the geographical area it inhabits, the weight of an adult male could reach 2.75 kilograms. The females are approximately 20% lower body weight than the male.

Source: Rafael M. Marrero Reiley

Although in past times the American black bear was in danger of extinction, the success of conservation policies has resulted in its population increasing. However, Ursus americanus continues to be under constant observation by the IUCN.

It is an omnivorous animal that feed on berries, nuts, acorns, strawberries, blueberries, blackberries, and seeds. It also eats ants and vertebrates, such as white-tailed deer and salmon.

Behavior

American black bears are very good swimmers. They usually climb trees to take their food or to flee from a predator. Although they generally feed at night, they are generally active at any time of the day.

The Ursus americanus tends to be a non-gregarious and territorial animal. However, if there is an area where food is in abundance, they could form groups. In them, the larger male dominates the group and marks the territory by scratching the bark of the trees and rubbing its body.

The American black bear communicates by making some vocal and non-vocal sounds. The most common are the clicking they make with their tongue and the grunts. If they are afraid they may moan or snort the air.

The pups scream when they have a problem and buzz while they are being breastfed.

General characteristics

Size

The American black bear is smaller in size than the brown bear. Weight will depend on sex, age and the season of the year. In the autumn season this animal gains weight, because its body stores fat, which it will use later in the cold winter.

The male can measure between 1.40 and 2 meters and weighs between 60 and 275 kilograms, with an average of 1.20 kg. In North Carolina, specifically Craven County, a male weighing 400 kilograms was identified.

The female weighs 40 kilograms to 180 kilograms and is approximately 1.20 to 1.6 meters long.

Extremities

The Ursus americanus is able to stand and walk on its hind legs, which are about 13 to 18 centimeters longer than the previous ones. It has five toes on each leg, with non-retractable claws that it uses to dig, rip, and climb trees.

The claws are rounded and short, black or grayish brown. The legs are relatively large, the hind legs measuring between 14 and 23 centimeters. The right blow of a leg is enough to immediately kill an adult deer.

Head

The American black bear has small, brown eyes. The ears are rounded and short. The muzzle is brown in color and is narrow and pointed. His sense of vision is not very good, but he can distinguish colors. On the contrary, their smell and hearing are highly developed.

The skull of Ursus americanus is wide, with a length of 262 to 317 mm. The face of females is usually thinner and more pointed than that of males.

Fur

Despite their name, the American black bear has a wide variety of colors in their fur. It is generally black in color, especially in eastern North America. Those that live towards the west are of a lighter tone, and can be cinnamon, brown or blond.

Those who live in Alaska and on the coast of British Columbia have creamy white fur. The species that occupy Glacier Bay in Alaska are blue-gray.

The muzzle is usually pale, in sharp contrast to its dark body. Sometimes you may have a white patch on your chest. The coat is soft, dense and with long hairs. The skin is thick, protecting it from the cold winter and from the bite of insects.

Hibernation

Previously, Ursus americanus was not considered a hibernating bear. However, recently studies were carried out on the changes that the metabolism of this animal undergoes when it is in a latent state for months.

As a result of these investigations, it can be said that this species does hibernate. The American black bear goes to its den in the months of October and November, although those that are to the south will only do it by females that are in gestation and those that have young.

Before hibernating, this species gains up to 14 kilograms, due to the accumulation of fat in its body, which will help it survive the months it will be in the cave.

Physiological changes

In hibernation time, the heart rate is reduced from 50 beats per minute to 8. Similarly, the metabolic rate decreases. These reductions in vital functions do not seem to influence the ability of this animal to heal the wounds that it may have during hibernation.

During this period, Ursus americanus does not feel hungry, as a consequence of the action of leptin. This special hormone suppresses the hibernating animal's appetite.

The American black bear does not excrete organic waste either, it conserves it in its intestine. This leads to the development of a hard fecal mass that forms in the colon, known as a fecal plug.

During this time, the body temperature does not drop significantly, so these animals remain somewhat active and alert. If the winter is not too bad, they might wake up and go out to find food.

Danger of extinction

The American black bear is part of the list of animals threatened with extinction, according to the IUCN. However, thanks to the success of conservation policies, its population has been increasing.

In the early 1990s, research in 35 North American states found this species to be either increasing or stable, with the exception of New Mexico and Idaho.

In Mexico it is listed as a species that is in danger of becoming extinct. The exception is the population of the Sierra del Burro, where it receives special protection, according to the Official Mexican Standard NOM-059-Semarnat-2010.

Causes

Since the time of European colonization, humans have been a threat to Ursus americanus. Due to their eating habits and the variation in the abundance of foods that are part of their diet, this species is strongly attracted to apiaries and agricultural crops.

People kill black bears to avoid damage to their property or for fear of being attacked by them. The clashes between Ursus americanus and humans became more frequent as people invaded the natural habitat of the bears.

The increase in the number of roads, with the consequent increase in vehicular traffic, is another threat that this American mammal has to face.

In relation to this, the lanes of a highway in North Carolina were increased from 2 to 4. In addition, the speed limit was increased on that section of the road. This negatively affected the nearby population, as it caused an increase in fatality due to run over.

Another problem, although not widespread in North America, is poaching. The legs and vesicles of the American black bear are sold at high prices in Asia, where they are used in traditional medicine.

Current situation

In most of the regions it inhabits, this species is not threatened. After many years of prohibition of hunting this animal, in Florida, Maryland, New Jersey, Nevada, Kentucky and Oklahoma they opened the hunting season. In Mexico, the capture of the American black bear continues to be illegal, although in some cases it is allowed.

Some small isolated populations may be threatened by environmental variations, food shortages or death from human actions.

In 2000 the southern part of North America suffered a severe drought. This caused an isolated population that was in Texas to migrate to Coahuila and Chihuahua, Mexico. The vast majority of black bears did not return, possibly they died crossing the desert or were hunted during the crossing.

As a consequence of this, the original population was reduced to 7 bears. However, this group has recovered rapidly, now exceeding the number of American black bears that existed before the exodus.

Taxonomy

Animal Kingdom.
Subkingdom Bilateria.
Chordate Phylum.
Vertebrate Subfilum.
Mammal class.
Subclass Theria.
Infraclass Eutheria.
Carnivore Order.
Suborder Caniformia.
Family Ursidae.

Genus Ursus

Species

Distribution and habitat

Ursus americanus lives in Mexico, the United States and Canada. In the United States, it is located in the Pacific Northwest, the Southwest, the Northern Rocky Mountains, the Northern Great Lakes, New York, and New England.

They are also in the Appalachians north of Georgia, the Piedmont region, the Ozark Mountains, Florida, and the Gulf Coast. In 1990, this species extended its distribution to Kansas, Texas and Oklahoma, where they were extinct.

In Canada they live in almost all regions, with the exception of Prince Edward Island and the farmlands of southern Manitoba, Alberta and Saskatchewan. The American black bear is rare in northern Mexico. In that country, this animal is classified as in danger of extinction.

Source: Rafael M. Marero Reiley

Habitat

American black bears prefer mesic sites and forests. They also live in swamps, wet meadows, high tide areas, and avalanche channels. The habitat of this animal is a combination of adjacent forest, edge habitats, riparian edges and forest openings, distributed over large areas.

The American black bear's use of habitat is determined by seasonal food production. During spring, it prefers meadows to forage for grasses and herbs.

In the summer it lives in avalanche channels or in early succession habitat. Mature forests are the favorites in the fall season.

Some geographic regions where it lives

Canada

On the coast of British Columbia, Ursus americanus prefers patches of forest, with woody debris, and late-succession forest. Alaska cedar and western red cedar are used as burrows. The reason is that the heartwood decomposes, keeping the outer shell hard. This offers them security and protection.

Alaska

In the interior of Alaska, the American black bear prefers, for the spring, the river bottoms. This is because there are the paper birch, the black poplar and the quivering poplar (Populus tremuloides).

In the summer they tend to look for blueberries, willow, dwarf birch and alder.

North America

On Long Island, this animal selects habitats that are dominated by Gultheria shallon and V. ovatum. For foraging they choose areas of early succession and late succession for burrow and cover.

These ecosystems are dominated by Douglas fir in dry sites, western hemlock in humid sites, and Pacific fir, western hemlock, Douglas fir, and mountain hemlock in high elevation sites.

During spring in the Southwest, this species prefers Gambel oak and mixed shrubs. If it is summer, they are located in riverside poplars, which have a large number of berry-producing plants. For the fall season, they look for Colorado pine nut seeds and acorns.

Habitat utilization in Florida may not change with the seasons, as many of these produce food year-round. Swamps and riparian areas are some of the busy areas in the coastal plain.

Mexico

In this country, Ursus americanus can be found in Sonora, Nuevo León and Cohauila. In relation to the state of Chihuahua, this species is distributed in the Sierra

Madre Occidental, in the central area of the Sierra del Nido and the Sierra de las Tunas.

Feeding

The Ursus americanus is an omnivorous animal. Their eating habit is influenced by the seasons, access to food, reproductive status, and human activities close to their habitat.

Due to their poor ability to digest cellulose, these animals feed on young, green vegetation. They generally prefer grasses and grasses during the spring. In the summer they select the soft masts and insects, and in autumn the nuts and acorns.

Some of the insects that make up the diet of this species are Camponotus spp., Formica spp and Tapinoma spp. They can hunt and eat salmon, white-tailed deer, elk, and bush red squirrels.

Feeding sites are located on rocky slopes, with elevations of up to 3,356 meters, with plateaus and banks covered with alpine tundra.

The most common soft-necked species that Ursus americanus eats are blueberries, blackberries, strawberries, and cherries.

The hard mast is an important food for these animals in almost all geographic regions. Some examples of these are acorns, walnuts, pinyon seeds, and limber pine seeds.

Reproduction

Females are sexually mature between 2 and 9 years old, while males do so when they are around 3 or 4 years old.

Females and males meet briefly to mate. During this season, the females remain in heat, until copulation occurs. The eggs that were fertilized do not implant in the uterus until the autumn time, so the pregnancy could last around 220 days.

Reproductive success could be related to the nutrition and diet of the female. These aspects also influence the size of the litter, which can vary from 1 to 5 young.

Young are usually born in January and February, while the female is hibernating. They remain in the cave with their mother throughout the winter. When they emerge, in the spring, the cubs can weigh about 5 kilos.

The female Ursus americanus take care of the young, teaching them the skills they will need when they are no longer with them.

Males do not participate directly in breeding. However, they protect the cub and the mother from other males that may approach the area where they are.