Taxonomy
| Polar bear | ||
| Ursus maritimus | ||
| Kingdom | Animalia | |
| Phylum | Chordata | |
| Class | Mammalia | |
| Order | Carnivora | |
| Family | Ursidae | |
| Genus | Ursus | |
| Species | maritimus | |
Description
The polar bear is the largest living land carnivore in the world today, with adult males growing up to 2.6 meters in length. The most well known of all bears, the polar bear is immediately recognisable from the distinctive white colour of its thick fur. A polar bear is so well insulated that its body heat is virtually invisible to a heat sensor. The only unfurred parts of the body are the foot pads and the tip of its nose, which are black, revealing the dark colour of the skin underneath the pelt. The neck of the polar bear is longer than in other species of bears, and the elongated head has small ears. Polar bears have large strong limbs and huge forepaws which are used as paddles for swimming. The toes are not webbed, but are excellent for walking on snow as they bear non-retractable claws which dig into the snow like ice-picks. The soles of the feet also have small projections and indents which act like suction cups and help this bear to walk on ice without slipping. Females are about half the size of males.
Polar bears feed primarily on ringed seals. Bearded seals are taken less often than ringed seals, but are important prey items. Polar bears also eat harp seals and hooded seals, and they scavenge on carcasses of caribou, musk-oxen, whale, walrus (usually pups) and seal. They occasionally eat mammals such as Svalbard reindeer and lemmings, as well as birds, eggs, lichens, moss, berries, grass and kelp.
Population size & trend
| Estimated population size: | Estimated population size: 20,000 — 25,000 |
| Trend: | decreasing |
Geographical range & habitat
The polar bear is found throughout the Arctic on ice-covered waters. There are no reports of polar bears in the vicinity of the North Pole itself. The northernmost location where they have been seen is about 160 km south of the North Pole, at 88°N latitude. The farthest south that polar bears live on a year-round basis is in James Bay (which is at about the same latitude as London) in Canada, where bears den at about 53°N latitude on Akimiski Island. They have also been recorded as far south as St. Mathew Island and the Pribilof Islands in the Bering Sea and Newfoundland in Canada, and they have occasionally been seen in the Gulf of St. Lawrence, Canada in years when heavy pack ice has been drifting farther to the south than normal (50°N latitude). The favoured habitat of the polar bear is on the annual ice that lies adjacent to the continental arctic coastlines or island archipelagoes. They tend to avoid areas of multiyear ice such as that which characterizes much of the northerly portion of the polar basin, probably because the density of seals is very low there. On the ice, the bears are found near the edges of the ice or in areas where the ice regularly cracks open because of the wind and currents and then refreezes. Seals are more abundant in these areas, and they are accessible to the bears when the seals surface to breathe in narrow cracks or at breathing holes in patches of thin ice that have just frozen over. |
Biology
| Female head-body length: | 1.9 — 2.1 m |
| Male head-body length: | 2.4 — 2.6 m |
| Female weight: | 200 — 300 kg (when pregnant up to 500 kg) |
| Male weight: | 400 — 600 kg |
| Cub weight: | up to 0.7 kg at birth |
| Age to maturity: | Age of first reproduction is normally 5 — 6 years for females. Most of the mating is probably done by males 8 — 10 years old and older. |
| Gestation period: | Relatively long (195−265 days) because of delayed implantation of the dividing fertilised ovum in the uterus. |
| Birth season: | Breeding from March to May; birth from late November to mid-January |
| Birth rate | The average litter size is less than two. Twins are most common in polar bears and account for about 2⁄3 of the litters. |
| Life span: | About 25 years for males and 30 years for females |
Conservation & status
| Conservation: | Following the drastic population losses of polar bears in the 1960s and 1970s, an international agreement was signed between the five nations with polar bears (Canada, Norway, USA, the former USSR and Denmark, which governed Greenland at that time). These nations signed the ‘International Agreement on the Conservation of Polar Bears’, and agreed to prohibit unregulated hunting and to outlaw the hunting of the bears from aircrafts and icebreakers. The agreement also obliged each nation to protect polar bear denning sites and migration routes, as well as undertake and share information on polar bear research. This was one of the first and most successful international conservation measures of the 21st century and was responsible for the recovery of the polar bear. The threats caused by climate change are now the main concern, especially as the rate at which environmental changes could occur may be faster than the rate at which many species can adapt. More than ever, the complexity of these issues and their global nature will demand international cooperation if this species and other wildlife is to survive. |
| IUCN Red list status: | Vulnerable (Red list) |
| CITES status: | Appendix II (Appendices) |
Threats
Polar bears are powerful predators which have no predators of their own, apart from human beings. They are living in an environment generally thought to be the cleanest in the world. To many people they radiate the impression of being unaffected by any human impact. This is far from the truth, and also to a large extent old news. The main threats to polar bears are: Climate change: Expected increased temperatures in the Arctic will result in retreat of sea ice. Because polar bears feed almost exclusively on ice-associated seals, changes in the sea ice that affect access to prey will have a negative effect on the bears. Polar bears are totally reliant on the sea ice as their primary habitat. If climate change alters the period of ice cover, bears may be forced on shore for extended periods and forced to rely on stored fat. If these periods become excessively long, mortality will increase. Especially, because the assumed ability of polar bears to physiologically compensate for extended food deprivation proved to be minor. There is no such thing as ‘walking hibernation’. Further, if the ice changes in character such that there is more open water, young cubs which are unable to swim long distances may suffer greater mortality. Pollution: Polar bears are the apex predator in Arctic marine ecosystems and are exposed to high levels of pollutants that are magnified with each step higher in the food web. It is reasonable to believe that the pollutants load of polar bears in some areas are negatively affecting the immune system, hormone regulation, growth patterns, reproduction, and survival rates of polar bears. Oil developing: Oil development in the Arctic poses a wide of range of threats to polar bears ranging from oil spills to increased human-bear interactions. Hunting: Polar bears are harvested in Canada, Greenland, Alaska, and parts of eastern Russia (Chukotka area) under provisions set by the International Agreement. Most polar bears are killed by indigenous people and this hunt has an important cultural role. The financial return from the sale of polar bear hides is also an important income for local people. Sports hunting can be a major source of income for remote settlements and the financial return from the hunt greatly exceeds that of the hide value. In Greenland, polar bear pants are popular with the hunters. Tourism: Tourism in itself is not a direct threat to polar bears but nevertheless, there are many situations in which carelessness or ignorance can result in the death of a polar bear. Tourism in the Arctic is increasing rapidly as people seek out new adventures. The number of conflicts with people will rise as the number of people in polar bear habitat increases.
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Zoos
| Zoos with polar bears: click here. Zoos with Polar Bears International Arctic Ambassador Centers lead the way towards animal welfare and conservation, because they: - Feature bear friendly exhibits with lots of enrichment activities to stimulate the bears to be active and content. - Teach about polar bears, climate change, the Arctic and how this can be supported. - Support PBI research projects to help conserve wild polar bears. | ||
| Studbooks | ||
| ISB: | Keeper: Rostock Zoo, Germany | ISB = International Studbook (WAZA) EEP = European Endangered species Programme (EAZA) ESB = European Studbook (EAZA) SSP = Species Survival plan Program (AZA) ASMP = Australsian Species Management Program (ZAA) |
| EEP: | Coordinator: Amsterdam Zoo, Netherlands | |
| ESB: | ||
| SSP: | Programme leader: Toledo Zoological Gardens, U.S.A. | |
| ASMP: | ||
References
Sources used
- ARKIVE
- IUCN Red list
- IUCN Polar Bear Specialist Group
- Summer declines in activity and body temperature offer polar bears limited energy savings (Whiteman et al., 2015)
More information
- IUCN Polar Bear Specialist Group
- State of the Polar Bear, an interactive exploration of the current population, habitat and threat information for the world’s polar bears
