Black Bear
There are 8 kinds of bears (Ursus) in the world
but I chose the North
American Black bear (Ursus americanus). I will be
covering general information
about the bear such as their size, weight,
color, food, etc., but I will
concentrate mainly on the hibernating cycle of
the black bear. There are from
400,000 to 750,00 black bears in North
America, and they weigh from 130 to 660
pounds with a body length of 50 to 75
inches. Their colors vary from black,
chocolate brown, cinnamon brown, pale
blue (known as glacier bears) to white.
Black bears will often have a
brown muzzle and may have a lighter color patch on
its chest. Its feet are
equipped with strong, highly curved claws. They’re
omnivores; eating nuts,
berries, fruits, insects (especially ants), deer and
moose fawns, carrion and
in coastal areas on spawning salmon. Their habitat
includes forests with
occasional open areas such as meadows. They occupy all of
Canada starting
from the tree line going south. They live in all provinces and
territories
except Prince Edward Island, where heavy de-forestation has happened
and
preferably away from brown bears (larger competitors). The only main risk
for
black bears are poachers who sell their parts illegally to the
Asian
medicinal market. In northern areas of Canada, the bear undergoes a
remarkable
metabolic transformation as it prepares for hibernation.
Hibernation is an
energy-saving process bears have developed to let them
survive for long periods
when there is insufficient food available to
maintain their body mass. When they
stop eating and become increasingly
lethargic, the bear will enter a cave; dig
out a den; or hole up in a dense
brush pile, hollow log or tree cavity and
hibernate. Right before it does
this it starts to gain weight so it can survive
the long months ahead. It can
gain as much as 30 pounds per week. The bear
hibernates between four to seven
months. When it’s in a hibernating state the
bear’s heart rate drops from
between forty to seventy beats per minute to only
eight to twelve beats per
minute. Its metabolism slows down by half, and its
body temperature reduces
by 3 to 7 degrees Centigrade (5 to 9 degrees
Fahrenheit). Also its body
doesn’t release any wastes like urea or solid fecal
waste but instead it’s
recycled into usable proteins. During the hibernation
period adult males and
adolescent bears lose between 15% and 30% of their weight
while a female cub
with newborn loses as much as 40% of her weight. Most black
bears vacate
their winter dens over a one to two month period starting in April
or May.
Both the climatic conditions (snow cover and temperature) and
physiological
factors such as the bear's age, the status of its health and its
remaining
fat reserves affect the time it comes out. Normally, adult males
emerge
first. Females with newborn cubs are usually the last ones to leave
their
den, and continue with their life
cycle.
Bibliography
I
only used the web to find information and
these are the sights I visited:
http://www.nature-net.com/bears/black.html
http://www.bearden.org