Closeup of a Black Bear

About Black Bears

Photo by Anne-marie Ferretti Mee

American Black Bear

The American Black Bear (Ursus americanus) is the most common bear in the United States and the smallest of the three bear species found in North America. The last known grizzly bear in Colorado was killed in 1979 and it is increasingly most likely with each passing year that any bear you see in the state is a black bear, regardless of its color.

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Black Bear near Durango, CO

The majority of Colorado's black bears live in the western half of the state. While it is difficult determining bear populations, Colorado Parks and Wildlife estimates the statewide black bear population to be around 17,000 to 20,000 animals.

They are omnivores, eating both plants and animals. Black bears are intelligent, creative and resourceful. They are remarkably tolerant of people. Bears are generally shy and wary, and prefer avoiding people as much as possible. Conflicts arise when bears obtain human foods and associate people and homes with food.

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Color: In southwest Colorado, 90% of black bears are some shade of brown. They may be cinnamon, honey-colored, reddish, blonde, black or brown. Individuals may change color drastically from year to year, or even in a period of months. See photo examples below.

Size: Black bears average three feet tall when standing on all four feet and five to six feet tall when standing upright.

Weight: On average, adult male bears weigh 275 pounds and females 175 pounds. Depending on the time of year, food supply and gender, they may weigh anywhere from 100 to 450 pounds. They are typically at their thinnest in early spring and at their highest weight in late fall. People tend to overestimate the size of black bears.

Sense of Smell: Astounding. Their sense of smell is seven times better than a bloodhounds and 100 times better than a human's. They live by their noses and can smell chicken cooking on an outdoor grill from many miles away.

Eyesight: Keen, similar to humans. Bears see in color, have good close-up vision and their night vision is excellent.

Hearing: Good. Bears hear high frequencies, exceeding human range.

Attributes: They can run in bursts up to 35 mph, climb trees with great ease and are strong swimmers. Black bears are incredibly strong. They are shy, their normal response to any perceived danger is to run away. Bears have great memories, handy for remembering the locations of food sources and they have remarkable navigational abilities. They are not nocturnal animals, but use the evening hours to avoid people.

Lifespan: Black bears can live 25 years in the wild, but rarely live that long.

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Black bears are omnivores, eating both plant and animal material. They are day-active and opportunistic feeders. Roughly 90% of a bears' diet is made up of vegetation. Black bears know their home, seasonal and annual ranges very well and are keenly aware of microhabitats that hold an abundance of food sources.


After emerging from dens in the spring, bears travel to lower elevations to feed upon highly digestible, fresh, young vegetation. Preferring aspen habitat at this time, they are consuming 2,000 to 2,500 calories a day, feeding on anything from grasses, flowers, leaves, roots, ants and larvae, beetles, elk calves and deer fawns, baby birds and animal carcasses. As vegetation begins to dry up and lose nutritional value, bears will head for higher elevations where moisture allows vegetation to remain viable. Those that linger at lower habitats will feed on wild crabapple, serviceberry and the like.


In late summer the majority of black bears migrate to oak brush habitats in search of berries and acorns. During this fall hyperphagia (feeding frenzy) phase, if the food supply is there, bears will attempt to build up enough fat reserves to get through the five to six months of food-less hibernation. They will feed up to 20 hours, consume 20,000 calories, and add two to four pounds of fat daily. For reference, 20,000 calories is roughly equivalent to eating 30 Burger King Whoppers or 95 Taco Bell soft tacos.

Bears may eat 20 to 30 pounds of berries and acorns daily. For reference, it takes 1,500 chokecherries to make a pound. In years of good production, bears will bypass mostly all other natural foods in favor of acorns. The most common cause of a lack of fall natural foods is a late frost or drought.


Black bears begin entering dens in mid-September thru late November. Females with cubs are the first to enter dens with adult males being the last. Bears enter dens not because of cold or snow but as an adaptation in dealing with dwindling food supplies.

Bears will hibernate in excavated dens, under trees, in rock caves or in hollowed-out trees and often will rake leaves, twigs and other plant material into dens as bedding. During hibernation, their body temperature drops about five degrees, its heart rate drops from 40 to 70 beats per minute to 8 to 12 beats per minute. Its metabolism lowers by half and they do not eat, drink, urinate or defecate for the five to six months spent hibernating. They can easily be awakened in dens and will move around on occasion or even venture outside for brief periods.

Bears may lose between 15% to 40% of their body weight during hibernation. Despite adding three to four pounds of fat daily in the fall, bears remarkably suffer no heart-related illness. They avoid bone loss by recycling calcium back into their bones, they lose fat but not muscle mass and their muscles don't atrophy.

Black bears begin emerging from dens starting in March with males emerging earlier than females by about two weeks. Females with new cubs typically are the last to exit dens. It is expected, with a changing climate, for bears to enter dens later and emerge earlier.


Black bear cubs are born in the den in late January and weigh about 10 ounces. On average, two cubs are born, although three is not unusual. Newborn cubs are barely the size of squirrels, and are born blind, toothless and covered with very fine hair. The cubs do not hibernate, feeding instead on milk from their mothers that contains 33 percent fat.

Cubs will weigh 10 to 15 pounds when they exit dens and are about the size of a volleyball. Only half of all cubs survive the first six months. In good food years, cubs will grow to 45 pounds their first summer and may weigh 300 pounds just two years later.

Cubs stay with their mother their first year and a half and learn how to protect themselves, locate food and climb trees. Much of what an adult bear knows it has learned from its mother in this formative time. By their second spring they will be self-reliant and will separate from their mother by late spring.

Black bears are slow reproducers. Males are capable of breeding at three years old, whereas females do not start producing cubs typically until they are five years old and only give birth every other year. Mating occurs in June. Females carry a fertilized egg in their womb for months and delayed implantation allows the mother a way out if foods are scarce. If she has not accumulated enough fat reserves by hibernation, she will reabsorb the fertilized egg rather than continue development of a fetus. In periods of poor natural foods fewer cubs are born and there is an increase in cub mortality.

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Black bears leave many indications of their presence, and being familiar with signs of bears is a good skill to have if you spend time in the wilds.


Black bear tracks are distinctive with the hind footprint resembling a person's. Bears walk with the soles of their feet flat on the ground and tracks show five toes, with the front print short and generally measuring four to five inches in width. The hind print typically measures about seven inches in height. Tracks do not necessarily indicate the size of a bear and claw marks are not always visible, although commonly appear in prints in sand and mud.


Black bear scat is easily distinguishable. Bears have fairly inefficient digestive systems and most foods pass straight through. A bear's diet is clear upon examination of its scat. In the spring, scat consists mainly of vegetation, mostly grasses. In the fall, it may be a mash consisting of acorns and berries, which are swallowed whole. Seeds pass through the digestive tract unbroken and able to germinate, making black bears important seed dispersers.


Black bears spend a lot of time in trees and climb trees when threatened. Cubs learn early to climb trees for safety and bears will climb aspen trees in the spring to reach catkins, a popular early food source.


Other signs of bear activity include overturned rocks or logs torn apart, both in search of ants, larvae and other insects. Bears often use trees and other objects as scratching posts and as a sort of message board for other bears, communicating gender, breeding status and more. Daybeds are often located in areas of shade, often near large trees, and sometimes ringed with scat. Bears will wallow in water to cool off. Because it makes for easier travel, bears will often use the same trails or roads people use.

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Hundreds of bears are killed in Colorado each year as a result of interactions with people outside of hunting. Once bears become conditioned to receiving food rewards from people it is very difficult to change their behavior and options are limited for wildlife managers. Bear management practices include non-lethal bear management, capturing and relocating bears and lethal removal.

Colorado Parks and Wildlife Two-Strike Policy

A bear whose behavior is problematic or threatening is captured, tagged for identification and relocated. If the bear continues unwanted behavior it is recaptured and humanely destroyed. A bear simply wandering through town does not warrant capture. A bear must do something to warrant initial capture including breaking into a garage, causing property damage or being considered a risk to public safety.


Over the years, wildlife agencies have tried to solve bear and human conflicts by capturing and moving bears. Although effective on some bears, one could argue that relocation isn't the solution to human-bear conflict. Relocating problem bears is expensive in manpower and cost, and most good bear habitat is already occupied by people or other bears. In recent years, an average of 65 bears were relocated by Colorado Parks and Wildlife annually statewide.

With exception, bears that have been relocated often quickly return to where they captured and resume their problematic behavior, continue problematic behavior in a new location, or are killed by other bears or in attempts getting back to their original home range. Relocation typically merely treats the symptoms, not the initial problem of bears accessing human foods. Whether a bear is moved or not, the initial reasons for how the bear was obtaining human food still needs to be addressed.


People have long attracted bears into residential areas with food rewards and then wanted bears punished with relocation or destruction for accepting an easy meal. Once these bears are removed, a void is created for other bears to move into this vacated habitat and problems merely continue with a different bear. Often, the initial attractants are left unaddressed. In recent years, on average 352 bears were killed annually statewide by state and federal wildlife agents and landowners as a result of conflict with humans. Landowners accounted for on average 150 of those bear deaths annually.

Photo by Derek Reich

Non-lethal bear management employs negative conditioning to modify unwanted bear behavior. Bears are intelligent creatures that have the ability to learn from both positive and negative experiences. When a bear approaches populated areas and locates human foods, and nothing bad happens to it, chances are it will return. Each successful visit reinforces this undesired behavior.

Non-lethal aversion techniques are designed to have bears associate areas with negative experiences. Aversive conditioning is time-consuming and needs to be consistently applied. Tools include pyrotechnics, noisemakers, rubber bullets and specially-trained Karelian Bear Dogs. Some western state and Canadian wildlife agencies have Karelian Bear Dog programs in place. Regardless, human food attractants need to be removed for aversive conditioning to be at all effective.


State wildlife agencies will sometimes supplement food resources, hay for example, for elk in times of poor natural food conditions or extreme weather. Many question whether the same couldn't be done for bears during years of natural food failures. Diversionary feeding of bears is not without either difficulty or concerns and retired black bear researcher Tom Beck wrote about the concerns with diversionary feeding of bears years earlier.

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Colorado Parks and Wildlife keeps annual statistics on all manners of black bear mortality, including bears killed by hunters and outside of hunting.


Previously regarded as pests, black bears in Colorado were declared a game animal in 1935 and afforded protection under state hunting regulations. Black bears are pursued in all manner of take including rifle, archery and black powder. Research and state wildlife agencies differ on what role hunting has on rates of human and bear conflict, with most concluding hunting having little to none effect. In recent years, hunters took on average 1,473 bears annually in Colorado.


Non-hunter mortality includes bears killed outside of hunting including collisions with vehicles, electrocution, destroyed by wildlife officials, shot by landowners or other. In recent years, on average 314 bears died annually statewide in mortality outside of hunting and lethal removal.


Natural threats to bears include drought, starvation, loss of natural foods, accidents, internal parasites, wildfires and other bears. Black bears are relatively disease free and have remarkable recuperative healing powers. Humans are responsible for most bear deaths, and human population growth, development and a changing climate are likely the biggest threats to bears in Colorado. With a warming climate it's expected for bears to spend less time hibernating, putting them on the landscape for a longer period of time and exposing them to more possible human-bear conflict.