Tuesday, June 12, 2012
Polar Bear Cubs - The Start of A Polar Bear's Life
Polar bear cubs start their lives as cute and cuddly youngsters.
This is in stark contrast to the majestic kings of the Arctic they will become if they survive to maturity.
Female polar bears have their first set of cubs between the ages of four and eight (usually at age five or six). Females in the Low Arctic wean their cubs as they approach their second birthday, while those in the High Arctic, where conditions are more a lot more harsh and demanding, care for their cubs an additional year
Polar bear cubs are most often born in pairs, but sometimes the litter contains three cubs and possibly only one cub. They're born between November through January in a den. These snow dens are known as "maternity dens" and are made to protect the newborn cubs from the freezing Arctic temperature extremes.
At birth, the cubs are 30 to 35 centimeters (12 to 14 inches) in length and weigh a little more than half a kilogram (about a pound) . Having no senses, during their first few vulnerable weeks of life, they nurse most of the time and stay as close as possible to their mother to keep themselves warm. The female has special crevices within which the cubs can get the warmth they need to survive.
Polar bear cubs are born small and helpless, with their eyes closed and their fur is very fine at birth, making the cubs look hairless. They get their first glimpses of their mothers after they open their eyes sometime during the first month.
The cubs grow very quickly while they're in the den, thanks to the calories in their mother's rich milk, which has a fat content of roughly 31% . Cubs often lie on there mothers belly to nurse while their mother sits back and puts her head back and seems to slightly move back and forth as if to rock the cubs. The cubs begin walking inside the den at roughly two months. During this time, the cubs still spend about 85% of their time in the den, sleeping there at night.
When she finally emerges with her cubs, most often in late March or April, she leads them to the sea ice so she can break her long fast by hunting seals. Cubs begin eating solid food at this time which is at approximately three to four months of age.
The cubs usually stay with their mother until they're 2 1/2 years old, although some bears in the Hudson Bay area wean their young at age 1 1/2 . When the cubs reach a point where they have suitable strength and coordination, and when they are able to walk well and respond to their mother's motion and sound commands such as stay or come, they are ready to leave their mother and the den.
During the time that the cubs are with their mother, they must learn how to hunt and survive in one of the Earth's harshest environments by watching their mother. A mother bear's success at hunting seals directly influences their well-being and determines whether or not the cubs will live or die once they are on their own. A mother will sometimes carry her cubs on her back through areas of deep snow or water if conditions are too hazardous for the youngster.
Once the cubs are weaned, either the mother bear or the male chases the cubs away so that they can begin life on their own.
Polar Bear Cubs and Environmental Issues
As you can see, Polar bear cubs are very vulnerable during their first few months. This period is the time during which most of the deaths from global warming and pollution take place.
Mother bears are feeding on polluted fish and seals. The pollution is stored in their massive body fat and when they have their offspring, they pass the pollution on to the young via there high-fat mother's milk. Often their cub's immune systems are too weak to fend off the toxins and the resulting complications, so they die.
Global climate change is shortening the time that bears have to breed and this means that they put off having their children until too far into the season. So, fewer bears are being born.
This double whammy is causing Polar bear populations to decrease dramatically.
One study estimated that only 43 percent of polar bear cubs in the southern Beaufort Sea survived their first year during the year 2000, compared to a 65 percent survival rate in the late 1980s and early 1990s.
Clearly, something must be done to maintain polar bear reproduction at a rate that ensures the survival of the species.
Article Source: http://EzineArticles.com/?expert=Steve_Bralovich
Article Source: http://EzineArticles.com/970486
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