Black Bear

Evolution

Subspecies: Olympic black bear, New Mexico black bear, Eastern black bear, California black bear, Queen Charlotee Islands black bear, Cinnamon bear, Blue bear, East Mexican black bear, Florida black bear, Newfoundland black bear, Kermode bear, Louisiana black bear, West Mexican black bear, Kenai black bear, Dall Island black bear, Vancouver Island black bear

How long has this species been in existence? The ancestors of today's black bear came across the Bering Land Bridge from Asia more than 3 million years ago.

Closest living relative to this species? The Asiatic Black Bear is the closest living relative to the American Black Bear.

What are the closest ancestors of this species? Bears evolved from the Miacidae-family of small, carnivorous, tree climbing mammals.

Description

Physical description: Bears are compact, with stocky legs, small eyes, short, rounded ears, short curved claws, and a short, inconspicuous tail. The black bear has a straight facial profile and a massive skull. Black bears are normally black, but can also be shades of brown to cream colored. They have brown muzzles, and occasionally a white throat or chest patch.

Key characteristics: 

• Impressive climbers

• Fast runners

• Skilled swimmers

• Great senses

Weight: Adult males average 250-600 pounds while females average 100-400 pounds

Size: Adult males measure 5-6 feet while females measure 4-5 feet

Life span: Bears are long-lived animals, capable of surviving 30 years in the wild. Their survival increases as they mature. Less than half of newborn cubs may die before reaching their first birthday, with starvation being a major cause of death. By the time bears in Maine reach 2 years of age their survival exceeds 90%, and nearly all deaths of adult bears are due to hunting or other human-related causes.

Differences between males and females:

• Females: Legs are shorter and not as straight. More tapered face. Dantier and smaller feet. If two or more bears are seen together then it’s likely a female and her offspring.

• Males: Faces are wider and blockier. Bodies appear more blocky and square-shaped. Neck is more stocky and short

Habitat

Black bears are common throughout the Pacific Northwest's forests and mountains. They are also found in forests throughout Canada, Alaska, the Rocky Mountains, the upper Midwest, parts of the southern U.S., the Appalachian Mountains, and down into Mexico.

Rainfall: <55 inches

Plants: Plants found in black bear habitats include many types of conifer trees including white pine (Pinus strobus), red pine (P. resinosa), jack pine (P. banksiana), balsam fir (Abies balsamifera), and black spruce (Picea mariana), and all play an important role in a black bears life. Clovers, dandelions, catkins, and grasses are also types of plants that bears feed on and are found in their habitat.

Animals: Mammals such as deer and moose live alongside black bears. Tigers, wolves, cougars, bobcats, and coyotes can all also be found in the same habitats as black bears.

Temperature: During the winter, while bears are hibernating, they can survive low outdoor temperatures. Their fur is designed to keep them warm, not cool. So they can't live in extremely hot climates. The forests that they live in average about 50 degrees Fahrenheit.

Terrain: Bears prefer areas with thick understory vegetation and abundant food resources. They tend to live at elevations of 1,300 to 9,800 ft.

Distribution

Continents: Only found in North America in countries from Canada to Mexico.

Invasive: Black bears are not an invasive species.

Diet

Food: Fruit, nuts, honey and other plant parts are favorites of bear. They also eat insects and sometimes fish, but most of their food comes from plants. Diet consists of 80% plants, 15% insects, and 5% animal matter.  

Frequency: During the summer months, bears eat about 5,000 calories a day or the equivalent of two large cheese pizzas. But as fall begins bears start preparing for winter by going through a process of increased feeding called hyperphagia. Both sexes will forage up to 18 hours a day and gain up to 1½ times their summer weight. However, in the winter bears can go up to 7.5 months without eating

How does it get its food?: In early summer, bears search for pockets of greenery in wet meadows and along creeks and rivers, on avalanche slopes, in aspen forests and along marsh edges. Bears that live near human development are often found grazing on the grasses of golf courses, ski runs, parks and other urban green spaces. Bears have an excellent sense of smell, and can easily find food using their noses.  

Special foods: They will also occasionally consume fish, honeycomb, and human food and garbage.

Social Structure

Solo or packs?: Bears are solitary by nature, except when in family groups of mothers and cubs or in pairs during the mating season. Bears may congregate in areas of high food density, such as oak stands, berry patches, or farm fields. 

Roles: Through their foraging habits, bears spread plant and berry seeds in their droppings and spread marine-derived nitrogen into the forest surrounding salmon streams. Bears are important links in food webs and help maintain populations of deer and other prey species through predation 

Dominance: Adult male black bears are the most dominant

Individuals in the group: Generally they are solo creatures. If they are found in a group it would be a mother and her cubs or a male and female during mating season.

Interaction: Bears often communicate with each other by marking trees with their scent. When abundant food sources are found across large areas, bears tend to tolerate each other more than usual, mostly because they cannot defend such a rich food source from competitors. While bears may defend a food resource or mate while they are present, bears are not territorial. 

Reproduction

Frequency of mating: Consequently, the most often that female black bears can mate, unless they lose their cubs prematurely, is every two years. 

Mating partners: Not only are male bears promiscuous, but females often have more than one mating partner.  Black bears are not monogamous.

Mating season: Breeding season begins in May and lasts until early July, with mating mainly occurring during June.  

Mating rituals: If another male arrives during the courting ritual, the males may challenge one another for dominance or they may fight if they appear evenly matched. Black bears use sounds, body language, and scent-marking to express their emotions of the moment.  

Number of offspring: A mother bear will typically give birth to one to three cubs at a time. 

Unique characteristics: Male black bears will find a female and stay for an hour or two while he determines if she is receptive to breeding, quickly moving on to the next female if she is not. 

Development

Stages of development: Cub--> yearling--> young adult--> mature adult

Age of sexual maturity: Male black bears typically reach sexual maturity at 3-4 years of age. Females generally breed for the first time at 3 to 6 years of age 

Activities and environment of stages: Males also increase their movements during this time to seek out receptive females. With so much movement, males can lose up to 20% of their fall weight. Females remain in estrus or breeding condition until bred or until the ovarian follicles begin to degenerate.  Within the breeding season, multiple matings may occur for both sexes.   

Differences between males and females: Females do almost all of the work. The females will bear and birth the children. Then take care of them when they're cubs. The males only work is to find females to mate with.

Causes of Death

Predation: Black bears may become prey to mountain lions, wolves, coyotes, bobcats, grizzly bears, humans, or other black bears. Cubs are especially vulnerable to predation by these other animals. 

Sexual competition: It can be stressful for bears to find mates which leads to sexual competition between males. Black bears will often fight each other for a female.

Disease: Trichinella parasites is an example of a disease that black bears can carry. It was found that 7 out of 120 black bears have it which is approximately 5.8%

Other causes: Once fully grown, black bears have no predators besides humans and other bears. Main causes of mortality are vehicle collisions, starvation, and poaching. 

Competition

Inter-species: Black bears can compete with each other when resources and food are scarce. Additionally, they will compete when trying to mate with the same female. 

Intra-species:  Black bears will compete with grizzly bears, deer, and wild hogs for food. However, they have an advantage because their claws are tightly curved for tree-climbing.

What do they compete over?: Since black bears coexist with many other species they often have to compete over food such as plants. They also compete over space, resources, and mates.

Affect of invasive species: Exotic species can take a huge toll on black bears. Invasive species can seriously hurt food sources of black bears. Species like the common dandelion, nonnative clovers, domesticated livestock, and lake trout are all examples.

IUCN Rating

Rating: Least Concern

Population: 250,000 to more than 300,000. 

Population trend: Black bear population has increased over the past few decades. In California, in 1982, the statewide population was estimated to be between 10,000 and 15,000 bears. Presently, the statewide population is conservatively estimated to be between 30,000 and 40,000 bears. 

Impact of Humans

Impact: Black bear populations are being depleted as a result of habitat destruction, over-hunting, international trade and human ignorance. As mineral and energy exploration, outfitting camps and road developments increase in the NWT, contact between humans and bears is rising. 

Future Impact: Humans continue to hunt, poach, protect their livestock. This is inevitably severley hurt black bear populations. The extinction of the black bears would leave a significant impact on an ecosystem. We know that black bears feed on herbivores species. So, if there are no black bears, the number of herbivores species will increase and as a result number of plant species will decrease since herbivores depend on plants. 

Length of human interaction: History of bears can date back to Roman Empire times. They saw bears as a symbol of nature’s power and savagery and this culture tortured bears to death. They would bring them into the coliseum and slaughter them, or use them to kill prisoners. Bear and human interactions have continued to this day and can even be seen in many aspects of our daily lives. 

Efforts: The most effective long-term solution to conflicts between people and bears is removing, securing, and properly storing attractants such as bird-feeders, garbage, grills, pet and livestock foods, livestock, and bee hives.