| || |
Black Bears - Physical Features
The American Black Bear's name can give misleading information about it's physical appearance. The majority of eastern black bears are black, sometimes with a white "v" patch on the throat and other markings on the chest, but many of the bears in the west are more likely to be brown and coastal areas of Alaska and Canada have bears whose coats are tinged with blue.
Despite their name, black bears' fur can range from white, cream, beige, cinnamon, chocolate, brown, smoky-gray and blue-black to black. In fact, cinnamon, brown and black bears can even be born within the same litter of cubs. The fuzzy, insulating hairs on the bear's undercoat are between 1.25 and 1.5 inches in length and the longer, black guard hairs grow to be 3 to 4 inches long.
The black bear is an omnivore that wanders in search of food. It has a life span of 20 years in the wild, but can live up to 40 years in a zoo. The black bear has forty-two teeth - the carnassial teeth for the shearing of meat near the front and the postcarnassials which have developed into flat-crowned crushing and grinding, molar-like teeth.
They are large, heavy animals with the boars weighing from 150 lbs to 400 lbs and exceptional records of over 600 lbs. A grown male bear stands 2.5 to 3 feet at the shoulder. Sows are much smaller and they do not usually exceed 150 lbs. These bears are usually around 5 or 6 feet from nose to tail in length, with a horizontal shoulder to rump line. Black bears have four powerful limbs and, like humans, have the ability to rotate their forearms, allowing them greater agility in seizing and holding prey. Each of the bear's feet have strong, non-retractable claws that are short and curved. The bear uses these for tearing, digging, climbing and occasionally, for fighting off other bears and animals.
These animals walk flat on the soles of their feet rather than on their toes like many other animals. This and their great size gives them a shuffling gait, but contrary to popular belief bears are not slow and clumsy. This is shown by the skill with they scale tall trees and how they can reach speeds of up to 30 miles per hour. Bears are also great swimmers and are able to swim miles without a rest. Their average swimming speed is 3 to 5 miles an hour and they walk at an average speed of 3 miles per hour.
The black bear has round, erect ears, a short tail and small, brown eyes that are situated on the front of the head. Bears are colorblind and they have poor vision because of the fact that usually live in fairly dense forests. Due to the conditions of their habitat, their senses of hearing and smell have adapted to become keener. Some bears are able to smell a dead animal from 20 miles away.
Black Bears - Location/Range
The black bear occupies most of North America from the Mexican plateau to the Arctic treeline in Alaska and Labrador. In Canada the black bear can be located in coniferous, deciduous and mixed forested areas from Newfoundland to British Columbia and can also be found in swamp lands and berry patches, depending on the season.
Black Bears - Habitat/Environment
Black bears range through many different physical landscapes, as long as they have vegetative cover and will roam up to 150 square miles across the land, looking for food. In the winter, bears prefer to be in swampy or coniferous forests because there is a greater chance of finding shelter for the winter. In the spring, bears move towards more deciduous forests and feed off of the leaves that are there and in the late summer and autumn, they will stay closer to pine forests where berry patches can be found.
Typical Spring Bear Habitat
Because the areas that they inhabit are usually close to human populations, they have lost their fear of man and sometimes, when they let their curiosity take over, they can become a nuisance to farmers and tourists.
The black bear makes it's winter den in hollowed out trees, caves or large depressions in the ground. Other than during the winter, bears do not have a permanent bed and will sleep in leaf filled depressions along their ranging routes.
Black Bears - ReproductionDepending on geographic location Black bears reach maturity between 3.5 years and 7 years of age. They are usually solitary animals, but will pair off at mating time. Copulation is similar to that of dogs and will last from 15 to 30 minutes. Mating occurs several times over a two to three week period, the male and female remaining together for up to a month during this time, before parting and going their separate ways.
Black Bears mate in early July until early August and fertilization will occur, but the embryo's development will be delayed until well into the autumn or early winter months. This is because of a survival mechanism known as delayed implantation. Delayed implantation allows the ovum to become fertilized at any time during the bears' mating season. One Ontario Ministry of Natural Resources biologist, George Kolenosky, figures that this is nature's way of waiting to see if the sow will find enough food to support herself and cubs through the winter.
The number of cubs largely depends on the amount of food that the mother can find during the fall. If she does not store a sufficient amount of fat, she will emerge in the spring alone. The more food that she consumes in the autumn, the more cubs she will give birth to.
The fertilized ovum will remain in a free floating stage until it finally implants itself into the uterine lining around November or early December. Once implantation has taken place, the gestation period is between six to eight weeks. Because of their brief gestation period the cubs are born small, weighing less than one pound each. The cubs are born in January or February and there can be up to four in a litter, with the average number being two.
A new cub is pink and hairless, weighing 10 to 12 ounces. It's thin eyelids are still closed and will remain that way until the cub is about 40 days old. The baby bear will use it's sense of smell to find it's mother's breast and will be fed exclusively on high fat and protein rich milk several times a day, for the next two months of it's life. During this time the cub will grow black downy fur, teeth and will open it's eyelids for the first time. The baby and it's mother will sleep until early spring when they emerge from their cave or other similar shelter. The cub will be about two months and will weigh approximately 20 lbs upon exiting the winter den.
Black Bears - Feeding Patterns and Relationships
Upon emerging from the den in early spring, the bear will be slow to eat and it will continue to lose weight for the next two to three months. The first things that the bear will consume are new grasses and sedges, with some ants and other insects for protein. It will take a few more weeks before it's digestive system is ready to digest meats and until then their diet will consist mainly of leaves. The fact that they continue to lose weight is connected with their bodies' inability to break down the leaves. Some researchers believe that the leaves just act as filler until more nutritious foods become available.
The black bear starts to gain weight by mid-July and will consume many strawberries, pin cherries, service berries and blueberries. A little later in the season the bears will eat an increasingly larger amount of insects, including ants, bees, wasps and caterpillars. In Autumn, Mountain Ash berries become a part of their diet. The picture below shows bear scat, primarily of Mountain Ash berries.
This closeup shows that this bear was feeing almost exclusively on Mountain Ash.
Bears will eat larger mammals when the opportunity is there, but instances of the bear actually killing another mammal are very rare. The meat that it usually eats is carrion left behind by other predators such as the wolf. Although some people believe that the bear is attracted to the smell of rotting meat, it actually prefers fresher kills and when happening upon an animal carcass, will sometimes eat only the freshest parts.
While 75% of the bears' diet is made up of vegetable matter, the other 25% comes from smaller mammals such as squirrels, birds and their eggs, insects and amphibians. The majority of their protein intake comes from insects; bears will use their claws to dig out ant hills and to break open hornets' nests. They are also great fishermen and climbers, using their skill to get fish from rivers and honey from wild bees nests.
Bears have no permanent bed and will wander for miles in search of food. Along the way they will stop for the night at various locations. The males will wander much further than a sow and her cubs and a boar's territory can overlap the territories of many females. With both sexes however, they will remain closer to their homes if the food supply is plentiful. In poor berry production years, Ontario Bear biologist, Martin Obbard, has radio collared bears, and found them up to 160 kilometers from the original collaring location.
Bears have an excellent homing mechanism as shown with one black bear in Michigan. It was brought, by air, 150 miles from it's home territory and found it's way back in less than two months. One brown bear in Alaska was moved to an island in Prince William Sound which was 58 miles away. Two months later, the bear was found dead only 100 meters from where it had been originally captured. To return to that spot, the bear had to swim 7 miles to one island, a half mile to another island and then 2 miles to the mainland, all against freezing water with strong currents.
Near the end of the summer bears begin eating larger amounts of food that has higher levels of fat, nutrients and protein. Before they den up for the winter, male bears can gain up to two pounds per day. This huge weight gain is important so that they will have enough fat to live of off during the winter. It is especially important for the females because it will influence the number of cubs that she will give birth to. This is nature's way of preventing starving. If there is not enough food, no more new cubs will be produced.