Black Bear Simulation


Black Bears Simulation


Animals need certain environmental conditions to survive.

Environmental factors include food, shelter, water

Organismsí needs fall within a certain range, but there are optimum conditions for survival

Components of habitat include crowding, carrying capacity, habitat loss, habitat improvement, herbivores, carnivores, omnivores, and limiting factors.

Food, shelter cover for feeding, hiding, bedding, traveling, raising cubs, and for denning.

With limited space adult bears will kill young bears or run them out of the areas. These bears must keep moving or find a vacant space sufficient for survival. social tolerances or territoriality of the animal.

Food climatic fluctuations, competition more intense move range or live on what is available and may put in a poor condition for winter hibernation.

Make five 2x2 green squares for each student

Mark each set with

B = bedding dense vegetation, rough terrain,  large trees, for bears to rest during day and night when not feeding

T = travel ways Sheltered areas where bears can move between food, water, and shelter with the aid of thick vegetation and rough terrain.

D = dens for hibernating from November to April. hollow logs, caves, holes in hillsides, under buildings, culverts. May use more than one a year and seldom use more than once.

H= hiding cover Black bears escape danger from predators and other bears by hiding in thick cover.

F = Feeding sites are usually less covered than the other areas. They are usually close to hiding areas or bedding areas for quick escape.

Food Cards make one 2x2 card of each color for every student.

Orange for nuts (acorns, pecans, walnuts, hickory nuts) mark 1 in 6 with N-20 and 5 in 6 with N-10

Blue for berries and fruit (blackberries, elderberries, raspberries, wild cherries) mark 1 in 6 with B-20 and 5 in 6 with B-10

Yellow for insects (grubs, larvae, ants, termites) mark 1 in 6 with I-12 and 5 in 6 with I-6

Red for meat (mice, rodents, peccaries, beaver, muskrats, young deer) mark 1 in 6 with M-8 and 5 in 6 with M-4

Green for plants (leaves, grasses, herbs) mark 1 in 6 with P-20 and 5 in 6 with P-10

 The following are estimates of total pounds of food for one bear in ten days

nuts 20 pounds = 25%

berries and fruit 20 pounds = 25%

insects for 12 pounds = 15%

meat for 8 pound = 10%

plants for 20 pounds = 25%

80 pounds = 100%

Water Cards make one and one-half 2x2 blue squares per student. Mark them with r = river, l = lake, st = stream, sp = spring, and m = marsh. One square would be needed for each black bear.


Focus Questions

What do animals need for survival?

What do you know about black bears?

What do you think black bears need for survival?


Adapted from Project Wild How many bears in the forest.

Background information

Elementary Project Wild 1983 edition

How Many Bears Can Live in this Forest? page 115-118.

The Black Bear Facts:

Source one of two


















Ursus Americanus

By Christine Kronk

Geographic Range

Black bears can be found from northern Alaska east across Canada to Labrador and Newfoundland, and south through much of Alaska, virtually all of Canada, and most of the U.S. into central Mexico (Nayarit and Tamaulipas states).

Biogeographic Regions:


Throughout bears' range, prime black bear habitat is characterized by relatively inaccessible terrain, thick understory vegetation, and abundant sources of food in the form of shrub or tree-borne soft or hard mast. In the southwest, prime black bear habitat is restricted to vegetated, mountainous areas ranging from 900 to 3,000 m in elevation. Habitats consist mostly of chaparral and pinyon-juniper woodland sites. Bears occasionally move out of the chaparral into more open sites and feed on prickly pear cactus. There are at least two distinct, prime habitat types in the Southeast. Black bears in the southern Appalachian Mountains survive in a predominantly oak- hickory and mixed mesophytic forest. In the coastal areas of the southeast, bears inhabit a mixture of flatwoods, bays, and swampy hardwood sites. In the northeast, prime habitat consists of a forest canopy of hardwoods such as beech, maple, and birch, and coniferous species. Swampy habitat areas are mainly white cedar. Corn crops and oak-hickory mast are also common sources of food in some sections of the northeast; small, thick swampy areas provide excellent refuge cover. Along the Pacific coast, redwood, sitka spruce, and hemlocks predominate as overstory cover. Within these forest types are early successional areas important for black bears, such as brushfields, wet and dry meadows, high tidelands, riparian areas and a variety of mast-producing hardwood species. The spruce-fir forest dominates much of the range of the black bear in the Rockies. Important nonforested areas are wet meadows, riparian areas, avalanche chutes, roadsites, burns, sidehill parks, and subalpine ridgetops.

Terrestrial Biomes:

Physical Description

Black bears are usually black in color, particularly in eastern North America. They usually have a pale muzzle which contrasts with their darker fur and may sometimes have a white chest spot. Western populations are usually lighter in color, being more often brown, cinnamon, or blonde. Some populations in coastal British Columbia and Alaska are creamy white or bluish gray. Total body length in males ranges from 1400 to 2000 mm, and from 1200 to 1600 mm in females. Tail length ranges from 80 to 140 mm. Males weigh between 47 and 409 kg, females weigh between 39 and 236 kg.

Black bears are distinguished from grizzly or brown bears (Ursus arctos) by their longer, less heavily furred ears, smaller shoulder humps, and a convex, rather than concave, profile.

Some key physical features:


The sexes coexist briefly during the mating season, which generally peaks from June to mid-July. Females remain in estrus throughout the season until they mate. They usually give birth every other year, but sometimes wait 3 or 4 years. Pregnancy generally lasts about 220 days, but this includes a delayed implantation. The fertilized eggs are not implanted in the uterus until the autumn, and embryonic development occurs only in the last 10 weeks of pregnancy. Births occur mainly in January and February, commonly while the female is hibernating. The number of young per litter ranges from one to five and is usually two or three. At birth the young weigh 200 to 450 grams each, the smallest young relative to adult size of any placental mammal. They are born naked and blind. Black bear cubs remain in the den with their torpid mother and nurse throughout the winter. When the family emerges in the spring the cubs weigh between 2 and 5 kg. They are ususally weaned at around 6 to 8 months of age, but remain with the mother and den with her during their second winter of life, until they are about 17 months old. At this time the female is coming into estrus and forces the young out of her territory. They may weigh between 7 and 49 kg at this point, depending on food supplies.

Females reach sexual maturity at from 2 to 9 years old, and have cubs every other year after maturing. Males reach sexual maturity at 3 to 4 years old but continue to grow until they are 10 to 12 years old, at which point they are large enough to dominate younger bears without fighting. Male black bears do not contribute directly to their offspring but do indirectly by deterring immigration of new males, thus ensuring territorial spacing and reducing the amount of competition for food.

Black bears can live to 30 years in the wild but most often live for only about 10, primarily because of encounters with humans. More than 90% of black bear deaths after the age of 18 months are the result of gunshots, trapping, motor vehicle accidents, or other interactions with humans.

Key reproductive features: gonochoric/gonochoristic/dioecious (sexes separate); sexual


Black bears are generally crepuscular, although breeding and feeding activities may alter this pattern seasonally. Where human food or garbage is available, individuals may become distinctly diurnal (on roadsides) or nocturnal (in campgrounds). Nuisance activities are usually associated with sources of artificial food and the very opportunistic feeding behaviors of black bears. During periods of inactivity, black bears utilize bed sites in forest habitat; these sites generally consist of a simple shallow depression in the forest leaf litter. Black bears are normally solitary animals except for female groups (adult female and cubs), breeding pairs in summer, and congregations at feeding sites. In areas where food sources are aggregated, large numbers of bears congregate and form social hierarchies, including non-related animals of the same sex that travel and play together.

Territories are established by adult females during the summer. Temporal spacing is exhibited by individuals at other times of the year and is likely maintained through a dominance hierarchy system. Males establish territories that are large enough to obtain food and overlap with the ranges of several females. The highly evolved family behavioral relationships probably are the result of the slow maturation of cubs and the high degree of learning associated with obtaining food and navigating through large territories. Black bears possess a high level of intelligence and exhibit a high degree of curiosity and exploratory behaviors. Although black bears are generally characterized as shy and secretive animals toward humans, they exhibit a much wider array of intraspecific and interspecific behaviors than originally thought. Black bears have extraordinary navigational abilities which are poorly understood.

Key behaviors: motile

Food Habits

Throughout their ranges in North America, black bears consume primarily grasses and forbs in spring, soft mast in the form of shrub and tree-borne fruits in summer, and a mixture of hard and soft mast in fall. However, the availability of different food types varies regionally. Only a small portion of the diet of bears consists of animal matter, and then primarily in the form of colonial insects and beetles. Most vertebrates are consumed in the form of carrion. Black bears are not active predators and feed on vertebrates only if the opportunity exists.

The diet of black bears is high in carbohydrates and low in proteins and fats. Consequently, they generally prefer foods with high protein or fat content, thus their propensity for the food and garbage of people. Bears feeding on a protein-rich food source show significant weight gains and enhanced fecundity. Spring, after the bears' emergence from winter dens, is a period of relative food scarcity. Bears tend to lose weight during this period and continue to subsist partly off of body fat stored during the preceding fall. They take advantage of any succulent and protein- rich foods available; however, these are not typically in sufficient quantity to maintain body weight. As summer approaches, a variety of berry crops become available. Summer is generally a period of abundant and diverse foods for black bears, enabling them to recover from the energy deficits of winter and spring. Black bears accumulate large fat reserves during the fall, primarily from fruits, nuts, and acorns.

Economic Importance for Humans: Negative

Black bears have been known to occasionally raid livestock, though losses to bears are negligible. Bears sometimes damage cornfields, and berry and honey production. Some bears have become troublesome around camps and cabins if food is left in their reach. Black bears have severely injured and sometimes even killed campers or travelers who feed them. However, the danger associated with black bears is sometimes overstated, fewer than 36 human deaths resulted from black bear encounters in the 20th century. Black bears are generally very timid and, unlike grizzly bear females, black bear mothers with cubs are unlikely to attack people. When black bear mothers confront humans, they typically send their cubs up a tree and retreat or bluff. People who live in or visit areas with black bears should be aware of the appropriate precautions for avoiding black bear encounters.

Economic Importance for Humans: Positive

People have intensively hunted U. americanus, for trophy value and for various products, including hides for clothes or rugs, and meat and fat for food. In most of the states and provinces occupied by black bears, they are treated as game animals, subject to regulated hunting. An estimated 30,000 individuals are killed annually in North America. Relatively few skins go to market now, as regulations sometimes forbid commerce and there is no great demand.

Medical research on the metabolic pathways that black bears use to survive long period of torpor is yielding new insight into treatments for kidney failure, gallstones, severe burns, and other illnesses.

Conservation Status

Black bears once lived throughout most of North America, but hunting and agriculture drove them into heavily forested areas. Residual populations survive over much of the range in sparsely populated wooded regions and under protection in national parks. They are numerous and thriving, but continue to face threats regionally due to habitat destruction and hunting.

Other Comments

Black bears can run as fast as 25 miles per hour while they chase prey, and they are skillful tree climbers.

Black bears are timid and secretive and rarely are dangerous unless wounded or cornered. They are often captured and tamed.

Christine Kronk (author), University of Michigan: October, 2002.


Academic American Encyclopedia. 1994. Grolier Incorporated. Danbury, CT.

Collier's Encyclopedia. 1993. Collier Incorporated. New York, NY.

Encyclopedia Americana. 1994. Grolier Incorporated. Danbury, CT.

The Carnivores. Ewer, R.F. 1973. Cornell University Press. Ithaca, NY.

Walker's Mammals of the World, 4th Ed. Nowak, Ronald, M. and John L. Paradiso. 1983. Johns Hopkins University Press, Baltimore, MD.

Wild Mammals of North America. Chapman, Joseph, A. and George A. Feldhamer. 1982.Johns Hopkins University Press. Baltimore, MD.

World Book Encyclopedia. 1994. World Book Incorporated. Chicago, IL.

Northwest Territories: Resources, Wildlife, and Economic Development Division, August 27, 2001. "Encountering Bears" (On-line). Accessed August 28, 2002  at

 2004/03/06 20:24:59.481 US/Eastern

To cite this page: Kronk, C. 2002. "Ursus americanus" (On-line), Animal Diversity Web. Accessed April 05, 2004 at

Disclaimer: The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.

Source Two

Ian Stirling, ed. Bears, Majestic Creatures of the Wild.

Emmaus, Pennsylvania: Rodale Press, 1993. 240 pages.

APPEARANCE This medium-sized bear is usually black with a brown muzzle, lacks a shoulder hump, and often has a white patch on the chest. Although black is the predominant color, chocolate and cinnamon brown color phases are also common,  which often results in people confusing them with brown bears. Black bears with white and pale-blue coats (known respectively as Kermode and glacier bears) also occur in small numbers. Kermode bears are found along the north-central coast of British Columbia, and the Yukon Territory, Canada. Black bears have strong, highly curved claws and the profile of the face is convex when compared with the more concave profile of a brown bear.

SIZE Adult male black bears range from about 130 to 190 centimeters (50 to 75 inches) in length and weigh 60 to 300 kilograms (130 to 660 pounds). Females measure from 130 to 190 centimeters (50 to 75 inches) and weigh 40 to 80 kilograms (90 to 175 pounds). Black bears vary considerably in size, depending on the quality of the food available. Males may be from about  20 to 60 percent larger than females. At birth, cubs weigh 225 to 330 grams (7 to 11 ounces).

HABITAT Black bears are normally found only in forested areas, but within such habitat they are highly adaptable. They live in both arid and moist forests, from sea level to over 2,000 meters (6,560 feet). Historically, black bears are  thought to have stayed away from open habitat because of the risk of predation by brown bears. Black bears have become established in the tundra of northern Labrador, a region where there are no brown bears.

DISTRIBUTION Black bears are widely distributed throughout the forested areas of North America although they have been totally driven out from some of their original range. They are presently found in northern Mexico, 32 states of the United States, and all the provinces and territories of Canada except Prince Edward Island.

REPRODUCTION Females reach sexual maturity at three to four years of age and males a year or so later. Mating takes place in June, July, and August, and pairs may remain together for only a few hours or for several days. Pregnancy last  s about 220 days, and the cubs are born in a maternity den in January and February. Litter size ranges from one to five, but two is the average. Cubs may be weaned at six to eight months, but they remain with their mothers for a year and a half. Consequently, the most often that female black bears can mate, unless they lose their cubs prematurely, is every two years. Longevity in the wild is 20 to 25 years.

SOCIAL SYSTEM Except for females with cubs, black bears spend most of their time alone. During the breeding season, a male and female may remain together for several days at a time and groups of bears may feed in close proximity to each  other if food is abundant, such as in berry patches or at dumps. Female home ranges are 3 to 40 square kilometers (1 to 15 square miles). While the home ranges of individual bears are usually exclusive from those of other bears of the same sex, male ho me ranges are larger and may overlap those of several females. A young adult female is often allowed to establish her territory within that of her mother, while subadult males must disperse.

DIET Black bears are omnivorous and feed on a wide range of foods, depending on what is available. Insects (particularly ants), nuts, berries, acorns, grasses, roots, and other vegetation form the bulk of their diet in most areas. Black bears can also be efficient predators of deer fawns and moose calves. In some areas of coastal British Columbia and Alaska they also feed on spawning salmon.  great set of slides


  • In a fairly large area (50 feet by 50 feet) scatter the colored pieces of paper. (I have done these activities all together by scattering the squares for shelter, water, and food at the beginning, giving each student an envelop that stands for different areas of shelter that they need to move among. Tell them that they should try to collect as many squares as possible, but they need to take each square at a time to their envelop which is to stand for their moving from one area to another.
  • Tell the students that they are black bears and they are to move as individual bears (review or explain the nature of bears and have students simulate their behavior) across the area and gather pieces of paper. Donít tell the students what the letters on the papers represent. Only tell them that the papers represent what bears need for survival.
  • When all the papers a retrieved have the students separate them into different piles according to their colors and letters.
  • Ask students what they think the letters stand for. Tell the students what the letters represent.
  • Have the students tell the different letters and how many of each they collected.
  • Encourage the students to predict what the different amounts and kinds suggest.
  • Tell them that the bears would need at least one of each letter on the green squares to survive.
  • Have the students share different possible scenarios. For example if a bear didnít get a D or den they would not likely survive the winter.
  • How many bears survived? What was the limiting factor for this population of black bears?
  • What other limiting factors could there be for black bears?
  • Ask students if they have what is necessary for them to survive.
  • Discuss.
  • Tell them that Black bear mothers would eat first and then their cubs, why?
  • Ask how many have enough so that if they were a mother bear with a cub that they and their cub would survive.
  • Ask if they think the simulation was appropriate.
  • Ask how many have enough so that if they were a mother bear with twin cubs that they and their cubs would survive.
  • Discuss


Dr. Robert Sweetland's Notes ©