The Eastern Arctic Seas Encyclopedia

2016 Edition
| Editors: Igor S. Zonn, Andrey G. Kostianoy, Aleksandr V. Semenov

Polar Bear or White Bear (Ursus maritimus)

Reference work entry
DOI: https://doi.org/10.1007/978-3-319-24237-8_402

Polar Bear or White Bear (Ursus maritimus) – a mammal of the Ursidae family from Carnivora order. It serves as a symbol of the Arctic. It is the biggest extant terrestrial carnivore. Adult male’s body length is 2–2.5 m sometimes amounting to 2.8–3 m. Female’s length is usually no more than 2 m. Adult males weigh 400–500 kg (in exceptional cases 800–1,000 kg) and females 200–300 kg (rarely 400 kg). Running speed can reach 60 km/h. The power of a paw blow amounts to 1 t. Apart from marking, it differs from a brown bear in the following aspects: it has a longer and narrower body, a long and mobile neck, and a relatively small head with a more strengthened profile. The ears are small, a little protruding from the hair coat. The feet are massive (especially on forepaws), with densely haired lower surfaces; the nails are slightly crooked, relatively short, and very sharp. The tail is short and hidden in the hair coat. The pelage is very thick in the winter, but it is shorter and less rough than that of a brown bear. In the summer the pelage is shorter than in the winter. The marking is similar for males and females and ranges from purely white (in the autumn and winter) and yellowish to straw colored (at the end of summer and closer to the end of life which is caused by greasy seafood), gray, and brownish. Long living on land devoid of snow covering accounts for the gray and brownish color of the pelage. P.B. molts almost all round the year. P.B. inhabits all the Arctic, to the south up to the northern mainland coasts, the southern boundary of drifting ice, and the northern boundary of warm sea currents (but not further to the south than latitude 50°N). Separate animals can be found still further to the south up to the Kola Peninsula, Kamchatka, and the Kuril Islands. The area of high density of polar bear population is close to the brim of solid ice, in particular the northern parts of the Barents Sea, the Laptev Sea, and the Chukchi Sea. In the recent century, the area and the boundaries of the P.B. habitat have changed very insignificantly, but the area of their high-density population has shrunk to a great extent. The current livestock population of P.B. in the Arctic is about 40,000 individual animals, of them up to 10,000 in the Russian sector. Usually, P.B. is active throughout the year and constantly roams around the ice, reaching the North Pole Region. They are drawn to waterfronts. While roaming, they often find themselves ashore and can linger there if the ice drifts away from the shores.

The main feed of P.B. is several species of seals, but mostly ringed seal and bearded seal. Depending on ice characteristics and season, P.B. changes the hunting strategy. On land it feeds on lemmings, birds and their eggs, and vegetable food, that is, low shrubs, herbs, and berries. It also eats different waste close to human settlements. It can suffer long-term starvation but, as occasion offers, can eat up to 20 kg and more of meat and fat at a time. On average an adult P.B. eats 5–8 kg of feed a day and hunts about 50 seals a year.

The rut happens in March and April. At this time, the animals go in pairs; sometimes the she-bear is accompanied by several males which often fight with each other. Pregnancy period lasts for 230–260 days. In September and October, pregnant females go ashore, more often finding the places that are not densely populated by people and lying on their nomadic migration ways (in Russia mostly on Franz Josef Land and Wrangel Island), where they go to rest into a bear den. More rarely, they find a den on mainland coasts or on sea ice. Within the period from December to February, the female gives birth to 1–3 (more often two and as an exception four) blind, deaf, and bare bear cubs weighing only 400–450 g. By the age of 3 months, they are already covered by thick fur and weigh about 10 kg. Now they are able to migrate with their mother. At the age of 8–10 months, the cubs start to procure the food for themselves, though they feed on their mother’s milk for more than a year. The family exists for about 2 years (a female usually bears its young once in 3 years). The animals become mature by 4–5 years old. The life span in captivity is 30–40 years. P.B. has virtually no natural enemies or competitors apart from humans. The cubs sometimes become victims of adult animals. P.B. is often contaminated with trichina and Ascaridae. Eating meat of P.B. that is infected with trichina may cause disease in a human (often with a fatal outcome). In recent decades, pesticides (including organochlorides) and heavy metals have been found in P.B.’s tissues. The accumulation of these combinations in the P.B. organism may cause less intensive reproduction. P.B. have long been hunted by the native population of the North for valuable skins, meat, and fat (the only inedible organ in a P.B. is its liver because it is too rich in vitamin A).

P.B. and its hunting have played a big role in rituals and beliefs of northern indigenous people. At the beginning of the nineteenth century in the Arctic 600–1,000, individual animals were annually hunted including about 500 animals in Eurasia. In 1930s, these figures reached 2,000 and 1,000, respectively. Later the hunting decreased. For a human, P.B. is not very dangerous which is due to strict specialization of its feed. But there have been cases of animals’ attacks on people, and in recent years, they have become more numerous as hunting for P.B. is now prohibited. It is very dangerous to come close to P.B. and its den, to feed the bears, and to make them accustomed to small handouts. The bears do some harm spoiling the Arctic fox traps, equipment, and stores of polar stations.

Protection measures toward P.B. have started in the Arctic region countries since 1930s when the population of the animals decreased abruptly. Since 1956, hunting P.B. has been prohibited in the Soviet and later in Russian Arctic. In 1973, the USSR, the USA, Canada, Denmark, and Norway signed an international agreement for P.B. preservation. It was prohibited to hunt them in all the Arctic apart from specially discussed cases. As a result of the measured taken, the P.B. population has increased to a significant extent. P.B. live well in captivity and are kept in many zoos of the world. Since 2008 there has been under way a program of research, distribution, and population of P.B. in the Russian Arctic by means of aviation and ship observations, their migrations have been traced with the help of radio beacons of the system ARGOS, the population structure of P.B. has been studied my means of molecular and genetic diagnostics, and the state of animal health has been assessed as well as the impact of various anthropogenic factors on them.

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© Springer International Publishing Switzerland 2016