Description

The polar bear is one of the largest four-pawed carnivores to walk the A482933 and can live as long as 25 years. Males are 8 to 11 feet long and weigh 500 to 1,100 pounds (227kg to 500kg) but can reach as much as 1,500 pounds (682kg). Whilst females only measure 6 to 8 feet long, and weigh from 350 to 600 pounds (159kg to 272kg), only occasionally reaching 700 pounds (318kg).

Keeping Warm

It may be thought that a polar bears trouble is being able to keep itself warm in the cold icy regions in which it inhabits as its body temperature is roughly the same as humans. In fact the polar bear is actually quite well adapted to this habitat having more than one way in which to keep warm. For one thing the polar bear has a two to four inch (5 to 10 centimeters) layer of blubber providing insulation from the cold air and water it roams about in as well as acting as a nutritional reserve in which to feed off when food cant be found. While a winter sleep can also provide a polar bear with the ability to keep warm. Usually undertaken by females who are expectant mothers, the winter sleep means entering a rest period in which the polar bears do not hibernate they just merely sleep in dens ready for their offspring to arrive. Polar bears also have little ears, a small tail and black skin which prevent heat loss. But probably the most talked about method of a polar bear keeping warm is through its hair. The theory being that a polar bears hair is made up of clear, hollow tubes filled with air that absorb the suns rays and provides a polar bears warmth. However what happens in the winter when there is no sun? this theory remains a controversial topic to this day. Whether this theory is right or wrong polar bears it seems actually have the problem of being able to stay cool rather than stay warm. Which is why it conserves its energy by waiting for a tasty morsel to eat by a watering hole.

Population

There are believed to be about 21,000 to 28,000 polar bear in the world, now that governmental regulations on hunting have been put in place, bringing about an estimated 10,000 increase since 1968. polar bear can be found in Greenland, A756236 the Arctic islands of A803422, A53443 and Russia and are part of A3851066

Range

The Arctic plays host to many a polar bear who are perhaps the most nomadic of all A1075655 species. There are two categories of polar bear in A259003 those in West Alaska named the the Chukchi/Bering Seas and the Beaufort Sea off northern Alaska. They travel an average of 5,500 miles a year or 15 miles a day.

Habitat

The Ursus Maritimus as it is scientifically known or polar bear inhabits the North Pole’s seas, ice, islands and continental coastlines. They prefer sea ice as habitat for it enables them to hunt seals in the leads (water channels, which only stay open for a limited time) that are in turn close to continental coastlines or islands. One particular region in which polar bear usually inhabit is known to be the 'Arctic ring of life', running alongside the polar basin coastline, this region is dense in rich system of leads and polynyas. Polynas can be defined as areas of water which are surrounded by ice that stay open throughout the year due to winds, upwellings, and tidal currents and they provide important breathing and feeding areas for wintering or migrating marine mammals and birds. It is also well known to people that the one-ton white bear is incredibly suited to swim the icy waters of the Arctic regions, because of its partially webbed feet and water repellent fur. But although water plays an importance in the life of the polar bear not all of them will be spending their time in the water all of the time. With pregnant female polar bears spending time on land in maternity dens and polar bears in warmer climates becoming stranded on land during the summer when the ice melts. The temperatures that surround polar bears in the wild appear to be -34C (-29F) in the winter and 0C (32F) during the summer. Northeastern Siberia plays host to the coldest temperatures during winter with people recording as low as -69C (-92F). While during the summer Siberia, Alaska, and Canada can reach the warmest temperatures of 32C (90F) and the ocean temperatures of the Arctic reach -1.5C (29F) in summer and -2C (28F) in winter when the seawater freezes.

Food

Polar bears are strictly carnivores hunting and living off a diet of ringed seal, bearded harp, hooded seals and the occasional baby walrus depending on the region they are found in. They scavenge Whale carcasses, Narwhals and Walrus, which sometimes enables people to see whole groups of polar bear feeding together. If any left overs are to be found after the polar bear have dissected their food then the Arctic Fox soon finds it. Of course when these mere delicacies to the polar bear are not to be found they wont go hungry instead they turn to other marine mammals, reindeer, small rodent, sea birds, ducks, fish, eggs, vegetation (including kelp), berries, and human garbage to quench their hunger. It is believed that a polar bear’s stomach can hold up to 15% to 20% of its body weight and digest 84% of the protein and 97% of the fat it consumes. While in order to survive the polar bear must consume around 4.4 pounds (2kg) of fat each day of its life. It is believed that a ringed seal weighing in at around 121 pounds (55 kg)could sustain energy in a polar bear for eight days. In order to find this succulent seal meal, polar bears have adapted to hunting. They wait patiently by the icy waters for the seal to raise its head then give them concussion by bopping them on the head with their paw or with a bite and throw them onto the icy surfaces next to them. Another tactic the polar bear have been able to adopt is stalking on land. Spotting the seal that has surfaced the seal is promptly stalked by the polar bear from around 15 to 30 m (49.98 ft.) away, then charged upon before it can retreat into the icy waters. The Aquatic Stalk also takes place by polar bear who acting like Jaws sneaks up to its food and snatches him from the ice edge. During spring polar bear even stalk birth lairs of the seals. On finding a seal’s lair the polar bear will wait patiently by the seal’s lair until it hears noise then it will smash up the lair and grab the seals it can find. This method is usually used by female Polar Bear who have young children of their own and believe that the seals would be sufficient meals for everyone.

Behaviour

The polar bears daily schedule mainly concerns two things saving energy and hunting and they don’t all hibernate in the way we would think. Pregnant female polar bears of course dig dens and hibernate in them, but other polar bears enter what is known as "walking hibernation" which means they stay actively searching out food to feed on, despite the fact that their metabolic processes decrease. Polar bear depend on their sense of smell to guide them to their food and their white furred coats provide the ideal camouflage in snow. Their day is broken up into three parts with the first third being when they are most active to the last part of the day when they become less so. Females are believed to hunt with their cubs just 19% of their time during spring and around 38% of their time during the summer. Adult male polar bears hunt about 25% of their time during the spring and about 40% of their time during the summer. If polar bear are not hunting they may usually be found sleeping or resting or even sun bathing if the temperature provides it. While the cold days provide the perfect excuse to go and find a shelter to kip in maybe for several months running at any one time.

Offspring

When female polar bears reach the age of five they are able to breed. Towards the winter months October to early November they go into A317116 in dens on the coastal mainland or on drifting pack ice, remaining in hibernation till early spring. To be successful in their pregnancy the polar bears have to obtain at least 441 pounds (200 kg). Many female polar bears give birth once every three years, whilst in others it occurs once every two years. Usually female polar bears give birth to at least two cubs although some polar bears have been recorded to produce a litter of four while others only have one. Each baby polar bear starts off weighing only a pound (0.5kg)at birth and quickly grow to 15 pounds (7kg) at which time they’ll be content to emerge in the spring. Learning from their mother the little cubs are quick to take things in and stay with their mother for around two years. Till they are chased off by their mother or a male polar bear desiring the mother bear to fall pregnant again.

Threats

Although polar bears are not federally listed as endangered or threatened they are under observation from many organisations such as ‘The International Union for Conservation of Nature’ (IUCN). Who realise that polar bears primary threat may be global warming. While chemical pollutants and proposed oil and gas development in Alaska could potentially lead to them becoming known as endangered species too.

Global Warming

Scientists believe that A197499 has affected the polar bears in terms of their body size and reproductive success, and has caused them to fast during the prolonged ice-free summers they now have to face. These ice-free summers have caused many polar bears to be stranded onshore for longer periods, and to lose a critical amount of their body weight in the process. Pregnant female polar bears are becoming increasingly unable to tend to their young properly because of losing so much body weight and producing little milk; sadly leaving many young polar bears to die. Some expectant mothers lose so much body mass that they are unable to give birth at all and this has led scientists to note a 15 percent decrease in birth rate.

Chemical Pollutants

Chemical pollutants also cause problems for the polar bear for they concentrate in the animals the polar bear feed on and provide immune deficiencies and reduce fitness in some polar bears.

Oil and Gas Development

Furthermore, there is a proposed oil and gas development on the Arctic National Wildlife Refuge in northeastern Alaska. Currently this region provides the wealthiest denning region for polar bear in the United States, but with the introduction of the proposed oil and gas development the species may be led to their deaths.