According to the definition, endangered species are those living creatures which are seriously at the risk of extinction. Polar bears are one such species that have been declared to be threatened, by the Endangered Species Act since 2008. Polar bears are the first animals that have made it to the list of endangered species, due to the problem of Global warming. In this article, we shall learn about – Why Are Polar Bears Endangered?
The scientific name of a polar bear is Ursus maritimus. It is the only type of bear that is recognized as a marine mammal. Polar bears live in the Northern Hemisphere, which is the Arctic region of North America and Eurasia. They can live on land and the ice of the sea. The countries in which they are generally found are Greenland (Denmark), Norway, Russia and Canada. They are also found in the state of Alaska in the U.S.A.
According to the recent researches, it is believed that polar bears evolved in the time span from 3.5 to 6 million years ago. They separated from their common brown bear ancestors. Over the years, they adapted themselves to live in the extremely cold climate of the polar region of Northern Hemisphere.
Polar bears are giant animals. Adult males weigh between three hundred fifty kilograms to six hundred kilograms or more. Adult females are comparatively smaller. They weigh between one hundred fifty kilograms to two hundred ninety-five kilograms. Generally, their body length is between 2 to 2.5 meters.
Lifespan of polar bears is 15 to 18 years, on an average. Some polar bears can also reach up to the ages of mid 30s.
Polar bears are adapted to live in the arctic environment, where the temperature falls up to -45 degree Celsius. Polar bears are covered by 2 fur layers, which keep them warm. When they are getting proper food and healthy surrounding, they also develop a thick layer of fats over their bodies. Polar bears have compact ears and tiny tails. So the heat loss from their bodies is very less.
Polar bears have feet covered with fur. Their feet also have papillae (small bumps) that prevent them from slipping. They are very sensitive to smell and can detect seals very easily. Their claws are very powerful and specially adapted to hunt for the seals from the sea.
Polar bears are carnivorous animals. They are very skilled hunters on land, as well as in sea. Their habitat has plenty of seals. So they depend mostly on the seals for their food. They can eat both ringed and bearded seals. If available, polar bears also eat the sea birds and their eggs. They also scavenge for dead animals in the sea like walrus and small whales. After eating, the fur and the skin of the polar bear turns a little reddish. Baby polar bears are not good hunters. So they are fed hunted food by their mothers up to the age of 2 to 3 years.
The exact population of polar bears cannot be traced as they are spread over various countries. The current estimation says that their population is 21,000 to 25,000. Their population and survival depend on many facts like environmental pollution, climate change, global warming and loss of habitat by human activities.
Polar bears are right at the top of the food chain. They consume the seals from the sea and prevent their over population. In past years, there has been a huge development in the oil and gas sectors, in the region of the habitat of polar bears. Actually, the baby polar bears are raised in these areas. So it is a great hurdle for the baby polar bears to reach adulthood.
Global warming has affected the habitat of polar bears massively. The change in temperature is very rapid in the Arctic region, compared to any other place. This is because of the global warming. The ice cap is constantly shrinking. The Arctic ice has started to melt and the ocean water has started exposing to the sunlight. This has an ill effect on the feeding cycle of the polar bears. Their breeding and habitat is also adversely affected. Hence, there will be a gradual extinction of polar bears, due to the degradation of their natural habitat. If this rate of global warming continues, most of the ice in the region of the Arctic will melt, by the end of this century. Hence, the polar bears will also be extinct.
In April or May, the polar bears feed heavily and then mate. After mating, the females dig dens in mountain slopes or hills, around the sea shores, in late October or early November. The cubs are born in these dens, in November or December.
At the time of the birth, the cubs are 30 to 35 centimeters in length. They weigh between half to 1 kilogram. Surprisingly, they are blind at the time of the birth. They are without tooth and have short fur. So they are completely dependent on their mothers for food and warmth. The cubs grow rapidly due to the rich calorie content in their mother’s milk. Birth of twin cubs is very common in polar bears. The cubs live with their mothers for about 2.5 years.