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.
Black Bears - Adaptations For Survival
To survive the harsh northern winters, black bears have many adaptations. The
bear grows two different layers of fur. The under layer of fur is shorter and
fuzzier and is there to insulate during the colder seasons. The outer layer of
fur or "guard hairs" are glossy black and grow much longer than the inner layer.
This system allows warmed air to be trapped in between and prevents heat loss.
The bear's winter coats are shed in the spring.
During the late summer and early autumn black bears gorge themselves on food.
They do this to gain an extra layer of fat to help in insulating and so that
their bodies will have nutrients during the winter. As the weather gets colder,
the black bear will begin to prepare a shelter for the winter. The shelter can
be a cave, a hollowed out tree or any other similar space. The bear will line
the bottom of it's den with grasses and leaves to lie on while it sleeps. Leaves
and other vegetation is raked from several yards around the den to provide both
insulation, and a comfortable bed for the winter.
As far as the true definition of hibernation goes, black bears do not
hibernate. During hibernation, the body temperature drops and the metabolism
slows. In the winter bears will go to sleep and their heart rates will slow.
Their breathing rate will also drop to 5 or 6 breaths per minute. In this state,
bears can sleep for extended periods of time and are capable of remaining in the
same position for up to one month, but will awaken easily if disturbed. If the
bear has not consumed enough food to last the winter, if it is an unusually warm
day or if it finds it's den uncomfortable, the bear will get up to eat or find
another shelter.
On common misconception about "hibernating" bears is that they do not excrete
bodily waste during the time that they are sleeping. Some people believe that
the bear will consume indigestible foods before denning up to create a fecal
plug. This is not true and even though they do not eat, they live off of stored
fat and do excrete some bodily wastes.
During the winter, black bears shed their foot pads and grow new ones. This
was not known by researchers until recently, but some of the native tribes
appear to have had past knowledge about this. Scientists are not sure why bears
do this, but it is probably the reason that they seem reluctant to venture far
from their dens. Their new foot pads are still too tender for long journeys.
Because they live in dense forests, black bears are sometimes thought to have
relatively poor eyesight.However, their sense of smell and hearing seem to
bevery sharp. To become aware of whatever dangers are around, bears will stand
up on their hind legs and sniff the air. This allows them to both see and smell
predators well before they meet face to face and helps them to find food as
well.
Cubs are very frisky and are sometimes hard for the mother to control, but
they are born knowing that when their mother gives them a warning growl, it is
time to be quiet. Coyotes and adult male bears are real threats to a baby bear
and some studies have reported that as many as 40% of new cubs are killed by
adult boars. When the mother growls, the cub will scamper up a tree and out onto
the thinnest branch that will support it's weight. There it will remain until it
is told to come down by it's mother. In the tree, the cub will be safe because
the thin branch is not enough to support the weight of any larger predator.
In the summer, bears roam in a very definite pattern searching for food. The
bears will mark these territories by urinating, defecating and by biting and
clawing at trees. These claw marks are a good indicator to other bears about the
bear who made them because they reach up as up as high as they can to make these
claw and bite marks.
The following photo shows a bear marking, made by scratching a balsam fir, in
northern Ontario.
Some male bears have ranges up to 150 square miles from their home territory
and females up to 50 square miles. On bear in Pennsylvania was tracked in an
area ranging to 380 square miles. In either case, if there is an abundance of
food, they won't roam as far.
When bears fear a conflict they will lower their heads, extend their lips,
chop their teeth and emit a low moan. This is usually a warning to the
challenger. They will also 'blow' pursing their lips, and expelling air, or
'woof' and snort. Bears are not usually aggressive animals and they will only
attack if they feel threatened or are injured. However, Black Bears do threaten,
and sometimes charge towards another bear, or person to protect a food source. A
mother bear can become fierce with the birth of her cubs and may attack if she
feels that their safety is being threatened. One study in the Great Smoky
Mountains National Park recorded 624 aggressive acts toward humans, but only 6%
(37) actually ended in contact.
Black Bears - Human Uses
In Ontario, the most important use that we have for bears is that they help
to support our economy. Local and professional outfitters offer hunting packages
for these animals and many people will come from other countries to hunt them.
80% of all black bears killed in 1989 were killed by non-residents. Bringing
tourists into our country helps to generate money. If the hunter stays in our
hotels or spends any money on entertainment while he or she is here, that is
money made for Canada. People who are here to hunt have to eat and will spend
money doing that. All of these things do not include the money that the hunter
is paying the outfitter for the hunt and the $125 non-resident liscencing fee
and a $30 export fee to take the hides and meat out of the province. In 1989,
resident hunters spent $4 million in travel, new equipment etc. and non-resident
hunters spent $10 million during their stays here.
At one time the bears' hides were used for rugs and robes for sleighs, but
now about the only use people have for their glossy black coats are for trophy
mounts and rugs and for the Queen's Guards Regiments tall fur hats.
Black Bears - How Black Bears Can Harm Humans
Black bears are considered a nuisance when they forage around garbage dumps
and campsites. They enter into our parks and communities because they have
learned that these places are an easy source of food. Bears also have the
reputation of raiding farms and eating their crops, especially corn and oats.
Bears begging for food in tourist parks have lost all fears of humans and this
is when they can become dangerous. In the wild, bears are afraid of men and will
usually retreat without confrontation, but nuisance bears do not fear humans,
and sometimes, will not retreat. Unless the person has a rifle, the bear will
likely win any contacts. Other than in these situations, or when the bear is
injured or protecting cubs, the incidences of bears attacking humans have been
fairly low.
Black bears can damage trees in the forest by clawing and biting to mark
their territory. One study found that in a certain area, 30% of the trees had
been damaged by the black bear.
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