In the labyrinthine Queen Elizabeth Islands of northern Canada Malcome Ramsay and his colleagues try to find answers for much of what they still don't know about polar bears.
The average size of a female polar bear is six-feet-eight inches, Weighs 368 pounds. The average male is seven- and -a- half feet long, Weighs 796 pounds, some males can weigh twice as much. Polar bears are often called the world's largest land carnivores. Their heads are more than 16 inches long and nearly a foot across. The paws are 8.5 inches wide, used for swimming and catching seals. Eighteenth- century European scientists named them urus maritimus, meaning ''sea bear''. They can swim 100 miles at a stretch. Most females return to land to give birth. The first bears go back almost 20 million years ago. Then they were only the size of small dogs. They began to grow much larger, some even larger than those do today.
Since 1968 researchers have detected toxic contaminants in the tissues of polar bears, this is far more threatening to their survival then hunting. They're finding organochlorines like PCBs, dioxins, and DDT in the bears' fat and milk. They're coming from Asia, Europe, and North America. They are passed up the food chain and concentrated in the bears' fat. Malcom tested a dozen bears in April and then again in May, levels of DDT, PCBs, and chlordane had increased between 12 and 34 percent.
During the summer when the ice melts, they can't hunt so they wander around. They're fasting sometimes called walking hibernation. Many wined up at Churchill, the polar bear capitol of the world. Sometimes they're put to death. Most times they're put in a converted warehouse that can hold up to 23 polar bears. They are kept there for a month and released north of town.
Since the early 1980's the weight of adult female bears at Hudson Bay has declined, as has the survival rate of their cubs. Ian Stirling, a veteran polar bear researcher with the service, believes it has something to do with climate change- including global warming. Malcolm doesn't completely agree with him. But he does agree that if global warming is affecting the Hudson Bay bears the consequences will be deadly. If the ice melts sooner in spring and freezes later in fall, the bears will no longer eat. They will fast until they starve.
While gorging on seals from April until early July, pregnet females can increase their body fat to 50 percent or more. They build up a five - inch thick layer of fat around the thighs and rump. Polar bears are masters at conserving energy. During the impregnated females eight - month fast they can lose 45 percent of their weight. It is important to stay warm and not use too much energy the bears' fur is dense, made of clear hairs that scatter light, creating a white effect. Their skin is black and absorbs the suns' rays. The long snout contains large membranes that warm and moisten the dry frigid air before it reaches the lungs.
Pregnant females need to put on well over 400 pounds of fat to sustain themselves and their cubs. They usually give birth in December or early January. In the den a female's heartbeat slows from about 60 beats a minute to less than 30 beats a minute. Only pregnant female polar bears spend the winter in dens. Most females deliver twins, but it's not unusual for them to give birth to triplets. At birth the cubs weigh around one pound. The mother nurses them with milk richer than any other bear. They leave the den around March or April. Most Hudson Bay bears leave their cubs around 1 1/2 months instead of 2 months. This allows the females to breed every 2 years instead of the usual 3 years. Given a chance males might kill and eat cubs.
Today scientists are still trying to find answers to their questions. Such as how many seals does a polar bear eat a week? They are hoping to find this out by attaching a collar fitted with a small video camera. New technology will play a part in future studies.
I think it's interesting how long polar bears can go with out eating. I never