Polar bear

The white Bear or polar bear ( Ursus maritimus or Ursus arctos maritimus ) is large a Mammifère originating in the artic regions. It is besides largest of the carnivorous S terrestrial and figure at the top of its food pyramid.

Adapted perfectly to its habitat, it has a thick layer of grease as well as a Fourrure which isolates it from the cold, the white color of its peeling ensures a ideal Camouflage to him on the Banquise and its black skin enables him to better store its body heat. Equipped with a short tail and small ears, the bear has a relatively small tapering head and a long body adapted to swimming.

The polar bear is a semi-watery Marine mammal, whose survival depends primarily on the ice-barrier and the marine productivity. It drives out as well on ground as in water.

Physical aspect

Cut and weight

The polar bear is - with the Ours kodiak - the largest alive terrestrial carnivore. It is twice larger than a Tigre of Siberia and weighs twice heavier than a Lion. The adult males weigh between 400 and 600 kg and can sometimes reach 800 kg for a size from 2,4 to 3 Mètre S. the bear presents a sexual Dimorphisme important: the females are generally twice smaller than the males, weigh from 200 to 300 kg and measure from 1,9 to 2,1 meters. With the birth, the bear cubs weigh only between 600 and 700 Gram S. the record of weight for an polar bear is currently of 1102 kg.

The polar bears have rather spectacular catches of weight. For example, in Canada, an polar bear female took more than 400 kilos in nine months. In November, it weighed 92 kg, but in August, it was weighed to 505 kg. This is explained by the grease of the seals which are eaten in spring.

Recent data suggest that the weight of the polar bears declines. These data can be taken as an indication of the pressures which weigh on them. A study of 2004 of the National Geographic Society showed that the weight of the polar bears, on average, was 50% lower than their weight in the Années 1970. As an example, in 2007, the females of the Hudson Bay had an average weight of only 230 kg, against a weight of 300 kg in the Années 1980.

Their weights do not prevent them from being very swift on the dry land. They can without problem exceed a man in race.

The polar bears are excellent swimmers thanks to their layer of grease. They can be seen on the open sea to hundreds of meters of any ground. They swim by using their front legs to be propelled and their back legs like rudder.

Skin and fur

The white Ours is immediately recognizable with its white Fourrure. With the difference of other Arctic mammals (such as the Arctic Fox), it never changes this peeling for a color more sunk into summer. The hairs are not really Pigment are in white; they not-are pigmented and hollow, like the Grey hair at the Homme.

An interesting characteristic of its Fourrure is that it appears black if it is photographed under rays Ultraviolet S. Certaines people put forth the assumption that the hairs dig drains collecting the light towards the black skin of the bear to help it to remain with the heat during the cold winters and without sun, but that is contradicted by more recent studies. Measurements show that the hairs strongly absorb the purple and ultraviolet rays. This is why the skin of the polar bear seems often yellow.

The polar bears renew their furs from May to August. The fur is usually of 5-15 centimetres on the major part of the body. However, on the forefeet, the males have hairs longer and growing in length until 14 years lâge. One supposes that is a form of attraction for females, with the manner of the Crinière of the Lion.

These bears are extremely well isolated; so much so that they catch hot with higher temperatures with 10 °C. So they were prélassent sometimes on the ice to cool; and on ground, they can dig with the research of the colder layer of Permafrost under the ground.

Evolution

Speciation

The raccoons and the bears diverged there are approximately 30 My. The Ours with glasses separated from the other bears there is approximately 13 My. The six species distinct from bear appeared approximately 6 million years ago. Fossil testimonys and the analysis of their DNA made it possible to show that the polar bear and the Brown bear diverged there is approximately: 200000 years.

The polar bears however have the possibility of producing a fertile descent while coupling themselves with brown bears, suggesting that they have a common ancètre near. What, according to the traditional definitions of a species (capacity to have a normally fertile descent), should make classify the polar bears and the brown bears within the same species.

In a largely quoted article of 1996, a comparison of the DNA of various brown bears of the islands Admiralty, Baranof, and Chichagof of the Alaska watch besides that these groups of bear divide a more recent common ancestor with the polar bear than with the other populations of brown bears of the world. From the point of view of the ascent, to define the whole of the black bears as a genetic group (a Taxon monophyletic) separated from the polar bears thus does not seem relevant.

Another index of proximity between black polar bears and bears, one can note that the polar bears still have substance HIT (“Hibernation Induction Trigger”, which helps with the Hibernation) in their blood, but without using it like the brown bear does it. They however can and occasionally to enter in a state of Somnolence (for the females in gestation in particular), even if the temperature of their body does not decrease for this period as that could be the case for hibernating mammals characteristic.

Although the traditional definition of the polar bear as separate species of the black bear appears contestable according to the taxinomic criteria traditional, none of the two species can survive in the ecological niche of the other. This is why, in addition to one morphology, of a social behavior, a rather different food and phenotypical natures, the two species remain classified like different today.

Subspecies and subpopulations

It is generally believed that there does not exist subspecies in the polar bear. Actually, since the crossings between Brown bear S and polar bears give Hybride S fertile, the polar bear is some times regarded as a under-representative of the brown bear. It is thus considered that there do not exist subspecies of the polar bear, but of the subpopulations.

The number of subpopulations depends much on the organism in charge on the enumeration. The IUCN/SSC PBSG ( Whodunnit Bear Specialist Group ), an important international body of research and management on the polar bear, currently recognizes a score of subpopulations in the world , . Among most known one can note:

  • Those of the Sea of Chukchi (Island Wrangel and west of Alaska)
  • Those of the Sea of Beaufort (Alaska of north and the North-West and Canada of the North-West)
  • Those of the Arctic Canadian archipelago
  • Those of the Greenland
  • Those of the Spitzberg - Ground of François-Joseph
  • Those of the Siberia of the northern center
Of these subpopulations, one counts 13 in Canada of them, counting approximately 15.000 individuals on the whole. and Ursus maritimus marinus .

The number of populations of declining polar bears increased, while passing from one in 2001 to five in 2006. There are only 19 populations of polar bears in the world, thus this decline represents more than one quarter of the populations of the species.

The decline of the populations of polar bears indicates that the whole Arctic is subjected to immense a Stress due to the Climate change. With the warming of the Arctic, which is more twice the more important than the rest of the world, and the fact that the ice-barrier must disappear the summer before the end from the century, the polar bears are vis-a-vis serious problems, especially because they depend on the ice-barrier to live, drive out and reproduire, .

According to a report lately published by the specialist group in the polar bears of the International union for the Nature conservation (UICN), the two subpopulations best studied polar bears in the world, the population of the west of the Hudson Bay to the Canada and the population of the south of the Sea of Beaufort (USA/Canada), knew a decline respectively of 22% and 17% during the two last decades. The three other declining populations are those of the Baffin bay and the Bassin of Kane - divided between the Greenland and Canada - and of the Baie of Norway in Canada.

The population of the polar bears is estimated in the Années 2000 between: 16000 and: 35000 individuals of which 60 % would live with the Canada and 25% in Alaska (the United States).

Geographical distribution and habitat

The polar bear is a species living on the level of the north pole, at the edge of the Arctic Ocean, whose habitat is limited almost to the ice-barrier. The southernmost point of their habitat is in the Baie James at the Canada. Although manpower decrease in the north of 88° of latitude, one can meet some in all Arctic.

The most populations are:

The extent of its territory is limited by the availability of benches of drift ice on the sea, which they use as platform of hunting for the seal, its principal food. The destruction of its habitat on the Arctic ice-barrier threatens survival even of the species, the polar bear then which can die out at the end of the century. Harbingers were observed at the south-western ends of its territory.

Lifestyle

Social behavior

The polar bears are solitary animals.

Food mode

In the family of the bears, the polar bear is the member with the most carnivorous mode, since it nourishes mainly Phoque S.

As a carnivorous predator, consuming fish, the polar bear introduces great quantities of Vitamine has, which are stored in its liver: in the past of the explorers of the Arctic were often poisoned by eating the Foie of an polar bear, because of a surdose of vitamin A.

Reproduction

The females are small (one or two in general) every three years old. They come in the world while the mother cut off herself in her den to winter: they do not awake it, being satisfied to nourish itself of the rich person mother's milk while tétant during several weeks. The mother takes along them out of the den only when they are old from three to four months: it is at this time only that they discover the world which surrounds them. The young people remain a long time near their mother. It is it which makes all their education: drive out, choice of a den, etc They separate definitively from the mother only at age the three years.

During this period, the small ones takes much weight thanks to the milk produced by an polar bear female which contains fat contents 50%.

Threats

The polar bear belongs to the red list of the species threatened of UICN (International union for the Nature conservation). Previously classified in the category “risks weak, depend on the efforts of conservation” according to the red list drawn up in 1996, the polar bear from now on is classified in the “vulnerable” category. It is estimated that the species could disappear within one century because of a reduction of the surface and quality of its habitat .

The habitat of the polar bears is naturally limited by the extent of the Banquise and the drifting ice floes of which they are useful as platform for hunting for the seal.

The survival of the polar bear is thus threatened by the Climate warming which restricts their habitat while dissolving the ice-barrier. The first signs of a decline were already observed in the zones more Méridional are of their habitat, like Hudson Bay. No alternative solution such as the introduction of the polar bear in the Antarctic is currently seriously considered.

The discoveries of drowned polar bears, of cannibalism, the number in increase of bear “with problems” - seeking bears of food close to the Arctic communities - are reported several areas to the range of the bears. These observations are coherent with the predicted changes caused by the warming of the climate.

Moreover, the widespread toxic matters in the sea are consumed by the Phytoplancton then the Zooplancton which in their turn are consumed by the fish, which themselves are eaten by the seals, the latter being the prey of the bears. Thus the bears store the poisons which accumulated in the organization of the animals which constitutes the food chain of the polar bears. One can also quote the exploitation of oil and gas like threats for the populations.

Drive out with the polar bear

Hunting for the polar bear is practiced by the Inuits and the hunters of trophies.

The the United States passed the Marine Mammal Protection Act in 1972 because the population of much of marine species had gone down drastiquement. The prohibited act to badger, wound or kill all the marine species Mammalian S, of which polar bears. It prohibits also the importation of “trophies” of polar bear in the United States.

The following year, 1973, saw off the creation of the International Agreement one the Conservation Whodunnit Bears (so known under the name of Agreement of Oslo ), signed by the five nations whose Arctic territories are inhabited by this species: the United States, Canada, Norway and Denmark (via Greenland) and Russia (at the time still the the USSR). He saw restrictions on hunting on the trophies and commercial and banishes hunting since the flying machines and the Brise-glace. For this year Norway has completely banished hunting for the polar bear and the United States, Greenland, Russia and Canada allows it within their people autochtones, leaving on the principle that it is part of their culture. Canada and Greenland allow hunting the trophies.

Canada, which shelters more polar bears that the other countries, allows a restricted hunting the trophies. The hunters pay heavy a tariff with the organizers of hunting to drive out polar bears. In 2005 the government of the Nunavut increased the quota with 518 bears, in spite of protests of several scientific groups; approximately 50 were sold with hunters of trophies, the number remaining given to of Inuit. The government of the Territoires of the North-West maintains its own quota from 72 to 103 polar bears within the community Inuvialuit; some are given to hunters of trophies.

Until 2005 Greenland did not impose limit on hunting on the polar bears by the indigenous population. This year it imposed a limit of 150 bears for 2006 and authorized hunting for the trophies for the first time.

In 1994 the United States modified the Marine Mammal Protection Act , allowing the importation of trophies of polar bears driven out by hunters of trophies and preparing the ground for a possible increase in hunting. For this year, more than 800 trophies of polar bears have been imported in the United States. In May 2007 a legislation was presented to the Congress to cancel the decision of 1994 and to prohibit the importation of the trophies.

Many associations of protection of the animals and environmental in general fear that the Climate warming does not have an enormous impact on the survival of the population of polar bears and that the continuation of hunting for the trophies does not have negative consequences yet.

State of protection

The five countries dividing the world population of polar bear, are the Canada, the the United States (via the Alaska), the Denmark (via the Greenland), the Norway and the Russia signed in 1973 the International agreement on the conservation of the polar bears (polar) and their habitat . This agreement indicates that these countries owe " to act like it convient" to protect the polar bear and its habitat. The protection of the polar bear is the particular classification object on certain territories:

  • the United States: December 27th, 2006, in answer to an ultimatum coming in the term one year after order from the course following an legal action by Greenpeace and two other ecologists groups, the Department of the Interior of the US government proposed " to actively seek comments and information scientifique" in order to determine if the polar bear were to be registered on the list of the threatened species. If such a decision were made, the US government would have obligation to protect the species and its habitat, the Banquise. According to the democratic member of Parliament ED Markey and the spokesperson of Greenpeace Kert Davies, that could result in a new American policy on the climate changes affecting the ice-barrier. For economic reasons related to the constraints that would involve on the oil exploitation in its state, the gouverneure of the Alaska, Sarah Palin, wrote a letter of protest at the federal government to protest against the possible inscription of the polar bear among protected spaces.

  • Canada: In November 2002, the polar bear was classified in the category of the “alarming Espèces”, i.e. among the species sensitive to the effects of the degradation of their habitat by the natural man or phenomena, but without being threatened of disappearance, by the Comité on the situation of the species in danger in Canada. Inuits would be in discredit of a more important protection of the polar bear which would involve the prohibition of its hunting, traditional activity of their people and important economically for them.

    • Quebec: The species is classified “likely to be indicated threatened or vulnerable”.

This interpretation is however disputed by other specialists, who call upon that there is a question of prospects comprising a share for refusal (as that of certain specialist relating to the fall in the stock of Morue of the Grands Benches of Newfoundland in the Années 1980) and for factors sociopolitic and economic related to the exploitation of the resources of large-north. The managing director of the Canadian Service of fauna, Michelle Brenning, adds that according to the figures of the government of Canada, among the 13 Canadian subpopulations, two are in increase, five are in maintenance of the number of individuals, five are declining and a population was not the subject of census, creating a heterogeneous situation of subpopulation in subpopulation. Various uses of the image of the bear cub were made, of the delicacy to the disc for child, with an undeniable business success.

In 1993, Coca-Cola is also known to have used the image of the polar bear for one of its advertizing campaigns. The bears were shown with Manchot S, although these animals live naturally in opposite areas. The Canadian coin of 2 dollars comprises the image of an polar bear. An polar bear was selected like mascot for the Winter Olympics of 1988 with Calgary and for the Université Bowdoin.

The inhabitants of the Territoires of the North-West of Canada have an polar bear on their plates number.

Appendices

  • Brown bear
  • the United States proposes to regard the polar bear as a species threatened on Wikinews.

Sources

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