North America is home to three species of bears: grizzly/brown bears, polar bears, and black bears. In the state of Missouri, there are only black bears.
Black Bears During and After the Ice Age
During the ice age, black bears were confined to the forest area that is now the United States and Mexico, including areas around the western mountains, swamps of the Gulf and Florida coasts, the Appalachians and the Eastern Coast. Due to the location of ice glaciers, species developed in isolation from each other. The glaciers prevented black bears living in different areas from breeding with each other which caused the creation of subspecies. As the ice retreated north, the forest expanded, along with the black bear’s range. In many cases, the black bear could not compete for territory with its more aggressive cousin, the grizzly bear. However, black bears were able to outcompete grizzlies in areas with relatively low densities of berries and other foods since they were smaller and able to subsist on less food.
Subspecies of Black Bears
There are 16 different subspecies of black bears in North America. A species is defined as a living thing that can produce fertile offspring. All black bears are capable of mating and having healthy offspring regardless of subspecies. Color is not a good indicator of subspecies because black bears can vary from black to blond fur. Distinctive features such as a large skull, big teeth, or a distinct raised sagittal crest may help set subspecies apart. Subspecies evolved because groups of black bears were separated from other groups of black bears due to the continental ice sheet. Other natural barriers such as waterways, mountains, or deserts also forced black bears into isolation. Once isolated, the populations began to develop small changes in their DNA and slight physical differences.
Black Bears are Adapted for Forest Life.
Black bears mainly live in heavily forested areas. They sometimes can be found near streams but will generally retreat to the woods if they see a human. The forest is a safe haven for black bears. Their black coat blends in well with forests and serves as effective camouflage.
All bears, even adult males, climb trees. They have curved claws that they use for climbing trees or seeking food. They climb trees by holding the trunk with their front paws and walking up the tree with their back paws, like an inchworm. If a mother bear senses danger, she will send her cubs up a tree. As the bears grow and increase in size, their agility lessens. Adult bears sometimes break branches as they climb through treetops in search of food.
Adult bears rely more on smell than sight. The nasal mucosa area of a black bear is 100 times larger than that of a human giving it a stronger sense of smell than even a bloodhound. They use their strong sense of smell to find food, locate a mate, or detect danger. Adult black bears have colored vision and can see in the dark. They are nearsighted which is an advantage for finding food but can be a disadvantage for distinguishing objects far away.
Black Bear Habitat
The ideal habitat for a black bear is a place that provides food, shelter, and water in ample supply and enables them to grow large and have multiple offspring. In the fall, when the acorns and berries ripen, the forest is the black bear’s main source of food. However, in the spring, open grasslands marshes and meadows also provide nourishment in the form of elk and whitetail fawns and a multitude of insects.
Black bears require sufficient tree cover to escape predators such as grizzlies and humans. In the west, where there are few grizzlies and humans, bears will feed part time on the open hillside. In the east, where grizzlies and humans are very active, bears are true forest animals. Their proximity to water also very important. In southern Canada and northeastern United States much of the forest cover is gone. Black bears need a minimum of 4,050 hectares to survive in rich habitats and 10,120 hectares in poorer habitats. Studies have shown that, when left on their own, black bears will regulate their own numbers. However, sadly, there are very few places in North America where black bears are not regulated by human activities such as poaching, hunting, and road accidents.
The black bear is built for strength with a large body and four powerful legs. It has a straight profile, round head, and large, erect ears. It has a short tail that is between three to six inches in length. There is a high variance in the weight of black bears because it is affected by factors including age, gender, season, availability of food and genetics. Generally, females weigh 175 pounds and males weigh between 250 and 300 pounds. Male black bears reach peak height and weight at age seven or eight. Males are generally one-third larger than females but size can vary. Black bears generally live 18 to 20 years. The oldest bear ever found in the wild was 31 years while the oldest documented in captivity was 44 years.
Differences from the Grizzly Bear
Black bears are often confused for their relative the grizzly bear. Like black bears, grizzlies range in color from blonde to black. Although grizzlies are usually larger in size, a large black bear can be larger than a small grizzly. The best indicators are shoulder size, profile and claw length. The grizzly bear also has a concave facial profile, smaller ears, and longer claws. The black bear has a flat nose, a droopy back, large ears and shorter claws. Additionally, the grizzly has a pronounced shoulder hump which the black bear lacks. The black bears have “droopy backsides that makes their back legs appear much shorter than their front legs, while the grizzly bears have straight backs.
The coat of the black bear has two parts, a soft dense undercoat for insulation and a coarse long outer layer that keeps the undercoat dry and clean. Not all black bears are black. They can also have white, blue-black, blonde, cinnamon or brown overcoats. Black bears frequently have lighter colored fur around their muzzle and will have blonde or white patches on their stomachs. Black bears of one color will regularly give birth to offspring of other colors and some bears’ coats will darken with age. In Missouri, however, black bears are predominantly glossy black.
Events Leading up to Hibernation
This should be prefaced with the fact that while black bears in cold climates go into deep sleep in the winter, they do not truly hibernate; their metabolic functions are cut by approximately 50%, however. The evolutionary change to becoming omnivores made it impossible for bears to survive the winter without going into “hibernation” because of the lack of plants and berries. In late summer to early fall, black bears will begin gorging themselves. During this period, they consume three times more food than in the spring and feed for up to 20 hours a day. Preceding hibernation, black bears gain up to a third of their body weight to build up fat reserves. This binge triggered by photoperiodism, the amount of sunlight and its angle triggers changes in chemical makeup.
After the feeding stage, bears will enter “walking hibernation” where they are alert but eat and drink very little. Their body systems slow down and their blood flow decreases. By now, they have chosen a den and begun to prepare it. Sometimes, bears will try out a site for a few days before deciding if they want to den there all winter. Scientists aren’t sure what prompts the final entry into the den. It could be prompted by a long snowfall or by the shortening days and decreasing amount and quality of food available.
The black bear dens are usually dry, located away from danger, and fairly cramped. Specific den spots are selected for privacy and security and should be unnoticeable unless covered by a layer of snow.They may be found be under brush piles, tree roots, beneath rock ledges, tree cavities, cavities created by erosion, or dug out dens. Dug out dens often collapse after use and therefore are seldom reused. Most dens just look like piles of snow, however, there is one telltale sign of a bear’s den- the breathing hole where the bear’s breath escapes. It acts like a chimney and exchanges air. It is easy to spot because frost crystals from the moist, expelled air create an entrance to the hole.
During hibernation, black bears’ heart rates drop down from 40 to 70 beats per minute to 8 to 10 beats per minute and their metabolism will function at 50% of its normal rate. Their body temperature will fall by 3 to 7o C and if it drops lower than 20o C, they will die.
Contrary to popular opinion, bears can be roused easily from a hibernating state, so if you are ever in a sleeping black bear’s den, do not wake it!
Black bears will lose weight during hibernation, but they use little bone or muscle mass. The bear’s metabolism burns fat, not carbs or proteins. The burning of these fats releases by-products, one of which is water. This allows bears to go all winter without drinking. Due to the consumption of fatty tissue, urine production is low. What little urea is produced is recycled. The result of this recycling is that bears never have to urinate or defecate all winter.
Mating and Reproduction
Birth of Cubs
In the early summer around July, a sow (a female bear) goes out to find a mate. Six to seven months later she gives birth during hibernation to two or three premature cubs. Why does she give birth during hibernation to premature cubs? She does this, because, if a cub was born in the spring, it would have to gain enough weight to go into hibernation the following winter. If a cub was born fully developed, it would place too much demand on sow’s resources. Black bears mate in July but the implantation of the fertilized egg does not happen until fall. If sow fails to gain enough weight by the winter, the embryo will fail to attach to the uterine wall and she will bleed out. If she does gain enough weight, the cubs will arrive between late December and early February. By giving birth during hibernation, the sow is conserving energy. It takes less energy to suckle a cub than to nourish it by placenta. The sow is partially awake for birth but is hardly aware of the labour. After the birth, the cubs will seek out mother’s nipples with no help from mother. The cubs are guided by the heat that radiates from their mother’s nipples. Newborn cubs are blind, toothless, and have poorly developed hindquarters so they have to drag themselves around using their front legs. While in the den, the sow will eat cubs feces in order to get rid of odors that might attract predators.
Mothers and Cubs
After a sow leaves the den, she will continue to fast for another two weeks and will continue to lose weight until mid-summer. When she does start to eat, she will eat green shoots of grasses, herbs and leaves. Carrion and prey are two other sources of food, but are less reliable. Throughout their first year and sometimes into their second, cubs will continue to suckle. This is a period of learning and experimenting for the cubs. They will chew on anything and will do whatever their mother does. They follow closely behind her and mimic her behavior. Mothers have been know to lead their young on treks up to 100 km from her home range in order to show her cubs seasonal riches such as berries or salmon. These treks usually occur in fall. During this time period, the cubs are the most vulnerable to predators. If the mother senses danger, she will send her cubs up a tall tree. They will then wait for mother to call them down.
Mother bears have a reputation of being one of the most watchful caring mammal mothers. Even though their natural instinct is to retreat, mother bears will challenge more dominant bears and will fight to the death if need be to protect her cubs. By fall, the cubs will mature and put on weight. By this time, they must be fat enough to make it through winter on their own. They can rely on body heat from their mother but nothing else. Yearlings may den with their mother the next year as well if she is not pregnant. However, males only den with their mothers for one year. Young male bears are curious and aggressive, necessary traits for them to establish a place of their own in the forest. They will travel 100 km from their home to ensure that they don’t mate with mother or sisters. Females on the other hand occupy part their mother’s home range. Although their contact decreases quickly in the female’s second year, the mother and daughter maintain an amiable relationship. On average, the size of their territory is between 15 to 25 km2. While some females will allow territory overlap with other females, others will fiercely defend their own. Only in an abundance of food will they tolerate each other.
Black bears have the lowest reproductive rate of North American land mammals. A 15-year-old sow may only produce six litter throughout her lifetime. Very few offspring survive to become adults.
The female black bear reaches sexual maturity in her third year. She will probably breed that year and once every two or three years after that. The richer the environment, the higher her reproductive success. By nature, black bears are solitary creatures and have adapted ways to hide from one and other. It can sometimes be difficult for a male and female to find each other in the forest. Because finding a mate is so difficult, two or more males may compete for the same female. Serious fighting may occur, leading to injury or death. When in heat, the female will travel her regular route more rapidly than normal to increase her chance of meeting a mate. Suitors are welcome from the time she emerges from the den to mid July. During this time period, the male black bear is also seeking mate. Males are capable of breeding since age four but barely get a chance until around age eight. The adult male has a range that overlaps with several females. The male will follow scent posts to where the female has urinated. During this breeding season, a hormone released in the female’s urine to let male know she is ready to mate. Eventually the two bears will meet. First, female retreats, leading him on a chase. Then, the distance will shorten once she know he is into to her romantically. This leads to face-to-face encounters that look, from a distance, like fights. Female will only permit mating during the middle of her estrus period, which is about three to five days long. During this period, the two will eat together, sleep together and mate frequently. Copulation lasts about 30 minutes although may last up to an hour. Scientists theorize that these long mating periods induce ovulation. After the mating period, the couple will split and the male will go try to find another mate. Females may find another mate as well, therefore it is not uncommon for twins or triplets to have different fathers.
Male black bears have a reputation for being “cub killers.” This behavior is usually linked to the male’s reproductive needs. A female bear will not come into heat as long as she is nursing. If something happens to her cubs, her milk will dry up and she will try to seek a mate again. It is in a female’s best interest to protect her cubs but it is in a male’s best interest to breed with as many females as possible. Therefore, mothers with cubs avoid males as much as possible and will protect their cubs ferociously.
In June, when male cubs are one and a half years old, they go their own way, leaving their mothers and siblings vulnerable to wolves, cougars and hunters. If they are able to survive, they will likely live long productive lives. Males do not stake out territory like females but instead will range over a large area that is 10 times the size of a female’s territory. This large territory will encompass several female’s range. Black bears will pace the same trail year after year. In some places, bears will pace the same trails for hundreds of years leaving the trails well worn.
Male black bears are more tolerant of other males than female black bears are of other females. If one male sees another one coming, he will turn and walk in the other direction. However, when it comes to mating, competition among males is intense and males must have the size and strength to dominate.
Black Bears as Herbivores
80-85% of the black bear’s diet is plant material. Bears will basically eat anything that grows. True carnivores, such as wolves and pumas, have shorter intestines than bears. Therefore, meat is digested more quickly. Since plant material is harder to digest, the bear gut has become elongated. A longer intestine allows bears to gain nourishment from plants. However, true herbivores, such as moose and elk, are more efficient at digestion. They have a much more highly developed digestive systems and can absorb between 45-60% of the food they eat, while, at most, bears will digest around 25%.
In the springtime, black bears feed on grass shoots, flowers, leaf buds, skunk cabbage, catkins and young leaves during what is called the “green-up period.” During this period, the plants have not had time for their cellulose to become firm. This allows bears to get the maximum energy from the plants with little time spent in their digestive tract. However, once plants have matured, their food value is minimal. Black bears do not gain weight during this period, but eat enough to maintain their current body weight. Black bears will also feed on the bark of tree, the soft cambium layer underneath the bark and the tree sap. During the summer, they will eat mainly berries. Berries are a high energy source of food and essential for the bear’s survival. Berries are what cause bears start gaining weight for winter. In the fall, the hard mast of nuts are also important for gaining weight. Bears will raid food storage areas of ground squirrels and will eat all of their nuts if necessary. Black bears will usually eat during the day, but in areas where they are hunted, they can become nocturnal.
Since black bears are omnivores, they are not viewed as as much of a threat by humans and are not hunted to the same extent as wolves. Wolves were almost hunted to extinction because farmers and ranchers were worried they would prey on their domestic animals. Since most of the black bear’s diet is plant matter, they are not seen as as much a threat and therefore are not persecuted at the same level.
Black Bears as Carnivores
Fifteen percent of the black bear’s diet is made up of animal protein. Even though it is a small portion of the black bear’s diet, it is a significant because the amount of protein from animal matter is far greater than the amount of protein from plant matter. Black bears are not especially suited for the type of hunting that other large mammals such as wolves and mountain lions do. They are flat footed and not fast runners. They are also not suited for stakeouts or ambushes because of their large size.
Actually, most animal matter black bears consume is insects. Black bears love snacking on ants and tent caterpillars. Honey is a special delicacy for bears. Bees will defend their nest by stinging the bear’s lips and nose, but the bears seem to be able to ignore the pain long enough to get the the honey.
Carrion is equally appealing especially if it has with fly larvae in it. A high proportion of the meat in bear’s diet is from animals they did not kill. However, if the opportunity presents itself, they will hunt and kill their own prey. Bears are opportunists and will attack injured or distracted animals. They will also attack small mammals such as mice, bird eggs, and young birds that venture too close to the stream. Bears will patrol calving areas of large mammals such as moose, elk, caribou calves, and deer fawn in hopes that they will be able to prey on the calves while they are still unable to run. When calves are born, their mothers lick them clean and eat the afterbirth to minimize the scent that would give away their hiding place. However, they do produce enough scent for bear’s sensitive nostrils to detect. Studies have shown that calf survival is much higher in areas without without black bears. Black bears have traditionally loved feasting on salmon, however, overfishing has greatly reduced the amount of salmon available.
Black bears will eat domestic animals if given the opportunity. Sheep, cattle, pigs and sometimes horses have occasionally been killed by black bears. Although, in most cases, it has been proven that the domestic animal died a natural deaths or was taken down by another predator and the bear was just feasting on its carcass.
Black bear scat is an important tool used to track, identify and protect the species. By examining bear scat, scientists can determine what the animal ate, what size it is and sometimes what subspecies it belongs to. Bear droppings, when firm, are tubular and look like human poop. Droppings found in the woods consist mainly of plant material because meat stools are runny and quickly absorbed into the soil. Plant stools last longer because the cellulose in plants is hard to break down.
The black bear serves an important role in the forest environment as a seed disperser. The piles of poop left on the forest floor promote the spread of plant species. Seeds of nuts and berries have protective shells that can’t be broken down by bears’ stomachs. When the seeds are left in warm pile of fertilizer, they are given the perfect environment in which to germinate. Plants in these “bear gardens” face tough competition among other germinating plants and must be strong to survive. However, rain breaks down the stool, spreads out the seeds and creates more opportunities for seed germination. Bears have the ability bringing to dead areas to life simply by depositing the seeds of colonizing plants in their scat.
Black bears leave a number of signs where ever they walk.
Bear tracks are very rare and hard to find. You are most likely to find them along wet trails or in the mud. Black bears are plantigrade walkers, meaning they walk on the soles of their feets. They wiggle when they walk because they are pigeoned toed with their feet pointing inward. Their walking pattern is both right legs forward, then both left legs forward. Therefore, the rear foot lands close to where front foot was placed. The normal stride walking stride of the black bear is 43.2 to 63.5 cm, and their running stride is twice that.
Bears will overturn rocks and ground cover when looking for insects.
Bears are frequently climb trees but finding their mark on trees is very difficult. The American Beech tree is a species that preserves bear scratches clearly. When the tree heals, the dark wounds remain where the bear claws dug in.
Look for a platform of branches in beech or other nut trees. The word nest is misleading because bears do not sleep in them. In the fall, they build platform from branches they can strip nuts from. In the winter, snow or strong winds will bring them down.
Bears will claw trees, to either mark their territory or show other bears how tall they are.
Bear dens are usually well hidden, mounds of snow. However, a tell-tale sign is the breathing hole. (Look in the den section above for more detail).
Even black bears have to worry about predators. Wolves and cougars will kill bear cubs if they are left unprotected. Wolves will also attack adult bears if they are injured or appear vulnerable. Large birds, such as the golden eagle and bald eagle, have the strength to pick up unprotected cubs. Domestic dogs can also be a threat. A large packs of dogs is more that capable of killing a small bear. Poisonous snakes will bite bears that wander too close and porcupines will shoot their claws at black bears if they feel threatened. Some internal parasites and bloodsuckers, such as tick and chiggers, depend on black bears for survival.
Since the 1960s, there has been a dramatic increase in the black bear population in the United States. In 1966, there was an estimated 148, 533 black bears in the United States. By 2011 there was an estimated 339,000- 465,000 bears in United States. This increase in black bears is due to better management techniques, better census methods, and more researches. Additionally, people are leaving the land and moving to cities, leaving forests to regenerate. Also people’s attitude about bears has greatly shifted. Black bears use to be viewed as varmints and there were few controls on hunting season. Now, the government enacted laws giving the black bear game status so that the season can be closed if necessary if their population numbers are too low. Not only has the number of black bears increased but so has their range. There are now black bears returning to states where they have be locally extinct for decades.
Black Bears in the US Prairies
Black bears have not traditionally been prairie dwellers. The presence of wolves and grizzlies kept black bears to the woods. When settlers killed off large predators and then took their place, black bears were not welcome as neighbors. However, black bears did find a home in the Ozark mountains. For a time period, black bears flourished in the Ozarks with the high elevation and heavy rainfall, until the settlers claimed this area as well.
The black bear was common in Missouri in the 1800s, but vanished by 1930s due to the clearing of the land for homesteading and logging, especially in Ozark and Ouachita Mountains. By 1894, the black bear was reported as locally extinct. However, a few bears may have survived. Some bears found their way up from Arkansas where they had been reintroduced. In 1991, a study showed some bears that walked across border mated with remnant Missouri bears that had survived the turn of the century. Today, the estimated population of black bears in Missouri is between 100 to 200 black bears. Most black bears in Missouri are found south of the Missouri river, though there have been some reports of bears in the northern counties. The species is listed as rare and a state policy being developed to protect black bear from ever becoming extinct again.
- Don’t run: Running triggers an attack response and you can’t outrun a black bear.
- Always face the bear: For some reason, predators are reluctant to face an opponent head on.
- Talk to the bear, quietly: Let it know you are there.
- Back up slowly, but keep your eyes on the bear: If given an option of fight or flight, black bears will take flight. If you get far enough away from the bear, it may disappear into the woods.
- Whatever you do, DON’T RUN.
Camping with Black Bears
According to the Missouri Department of Conservation, these are the Ten Commandments of Camping in Black Bear Country:
- Keep a clean camp. Thoroughly clean all utensils immediately after use. Never deposit food residues such as cooking grease in campfires.
- Place garbage where bears cannot smell or gain access to it, either in bear-proof containers or dumpsters. DON’T burn or bury garbage. Bears will dig it up.
- Do not eat or cook in your tent. Avoid storing food or attractants in tents, sleeping bags or backpacks. Suspend such items from trees when backpacking.
- Treat nonfood items such as gum, soap, toothpaste or deodorant as food. They are attractive to a bear’s acute sense of smell.
- Immediately store food articles (including pet food, livestock feed and garbage) in airtight containers after every use. Coolers are not airtight, and bears often associate them with food. Secure coolers in a locked trunk or truck cab concealed from view.
- Plan your meals. Generate as little food garbage as possible.
- Never attempt to feed a bear or any other wild animal.
- Never approach wildlife, especially black bears. They are dangerous.
- Keep your dog on a leash and clean up leftover food and scraps after your dog has finished eating.
“BLACK BEAR.” Missouri Department of Conservation. Conservation Commission of Missour, n.d. Web. 8 Oct. 2015. <http://mdc.mo.gov/discover-nature/field-guide/black-bear>.
Schwartz, Charles Walsh., and Elizabeth Reeder. Schwartz. The Wild Mammals of Missouri. 2nd ed. Columbia: U of Missouri, 2001. Print.
Taylor, J. David. Black Bears: A Natural History. Markham, Ont.: Fitzhenry & Whiteside, 2006. Print.