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The smallest and most common bear on the North American continent is the American
Black Bear. Growing to an average 5 feet in length and weighing between 200-300
pounds (some weighing as much as 500 pounds), these bears are also among the most
pursued by hunters. Not all black bears are completely black however, cinnamon,
brown, and even blonde are very common.
Because of it's very adaptive nature, black bear distribution originally spanned
the entire North American continent. However, due to over hunting of these bears
throughout the late 1800's and early 1900's the black bear can now only be found
in about 15 U.S. states, most all Canadian provinces, and some central regions of
Mexico.
Because of the reclusive nature of these bears, estimating this population can be
a very difficult task. Additionally, bears can travel great distances in search
of food, sometimes crossing agency and political boundaries, making the task even
more daunting. It is estimated that at the time of the first American settlers the
population of black bears was at around 500,000. Today that number is said to be
much higher, closer to 700,000 bears throughout the current home range, despite
it being much smaller.
Black bears can be found in a wide variety of habitats across their home ranges.
Although these bears prefer larger forested areas with a lot of underbrush, they
have also been documented on ridgetops, in tidelands, agricultural fields, swamps,
and even the dryer sage habitats of the far western states. Black bears typically
hibernate in dens throughout the winter; finding shelter in hollowed out tree cavities,
under larger logs and rocks, caves, and some shallow depressions. The bear will
usually not eat, defecate, or urinate during hibernation. However, black bears do
remain at least somewhat active, female bears even give birth and nurse their young
during this time.
Once spring arrives, black bears will emerge from their long sleep to venture out
in search of food. Most commonly the carrion from winter kills, including deer,
moose, elk, and smaller animals. Along mountainous home ranges, these bears can
be found searching the southern slopes at lower elevations, where the sun will remove
snowfall amounts at a faster rate.
Female black bears reach breeding maturity at 3 or 4 years of age and can breed
about every 2 years. In poorer environments, females may not reach breeding maturity
until 5 or 6 years, even skipping some years' breeding cycles entirely. Male bears
reach sexual maturity at about the same age, but may not win breeding rights because
of size. Similar to most mammals, bears often fight for breeding rights to be accepted
by females.
Black bears generally mate during the summer from mid-June through mid-August; depending
on the region. Embryos however, do not begin to develop until fall when the female
dens. The actual embryo development is about 60 days, although average gestation
periods last 7 to 8 months. If the mother did not store adequate fat and protein
amounts to sustain her through the long winter, and hibernation, the embryos will
not develop.
Black bear cubs are generally born throughout January and February. At less than
1 pound, they are completely helpless when born. Average litters produce between
2 or 3 cubs at a time. Although it is not uncommon to see litters of 4 or more.
The cubs remain with their mother for the first 1 1/2 years of life. It is at this
time the female will go into estrous again.
Black bear cub survival is completely dependant on the mother. She must show them
how to forage, where they must den, and where to hide in case of danger. Black bear
mortality rates are often high.
Black bears primarily consume grasses and forbs throughout spring, mast and shrub
born fruits in summer, and mixtures of hard and soft masts throughout fall. Although
bears can be opportunistic predators, most animal consumption is in the form of
carrion. A small portion of their diet also consists of colonial insects and beetle
species.
Diets of black bears is generally high in carbohydrates, consequently lower in protein
and fats. However these bears generally prefer foods containing higher proteins
and fats. As black bears emerge in spring from their winter dens, they tend to continue
to loose weight with food scarcity. During these periods, they continue to survive
partly off the body fat that was built before winter the previous year. With summer,
and the many diverse food groups that will flourish in bear ranges, recovery from
the energy and fat loss from the previous year is important to their survival. Black
bears will begin accumulating large fat reserves again as fall approaches, primarily
from fish, fruits, and mast.
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