Black Bear Ursus Americanus Essay Research Paper

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