Systematology

Class: mammals, order: carnivores, family: bears, species: polar bear
Scientific name

Ursus maritimus (Phipps 1774), Latin for "Bear of the Ocean"
Descent

Evolved from Siberian brown bear, presumably 200,000 to 300,000 years ago
Characteristics

* comparatively slim body with long neck
* narrow head with small eyes and outer ears
* paddle-like paws with webbed toes
* short tail (7 to 13 centimetres)
* five short, non-retractable claws
* body covered with hair, with the exception of the lips, the nose and part of the soles of the feet
* underwool up to 5 centimetres, guard hair/ top hair at the belly up to 15 centimetres
* heat-insulating layer of fat under the skin (up to 10 centimetres)
* hairs hollow, almost transparent and light-conducting
* 42 teeth

Colour

* fur white to yellowish white
* skin, lips, nose and claws black
* tongue blue

Measurements

* largest living predator on land
* male: 2.0 to 2.6 metres, rarely over 3 metres in length, shoulder height up to 1.6 metres
* female: 1.8 to 2.1 metres in length, shoulder height up to 1.4 metres

Weight

* adult male: 300 to 800 kilograms, according to historic reports up to 1 ton
* adult female: 150 to 350 kilograms, pregnant female over 500 kilograms

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Distribution

* across the entire North Pole area, mainly north of the Polar Circle
* Alaska, Canada, Greenland, Spitzbergen and Siberia
* Individual animals observed between 46 and 88 degrees north

Habitat

* North Pole Sea (pack ice, ice fields)
* islands and coastal strips (tundra)

Roaming area

* Polar bears can cover distances of many thousand kilometres each year.
* Every year, they roam 10,000 to 600,000 square kilometres.

Sense Organs

* Their sense of smell is excellent. Polar bears can sniff the snow-covered breathing hole of a seal from a distance of one kilometre. They can probably smell cadavers from a distance of 30 kilometres.
* Their hearing is a bit better than that of humans.
* Their sight is comparable with that of humans.

Movement

* Polar bears walk on the soles of their feet.
* Walking/Running: up to 70 km per day, short sprints at over 40 km/h
* Jumping: on land up to 4 metres and 2.3 metres out of the water
* Climbing: for example on steep slopes of up to 45 degrees incline
* Swimming: speeds up to 9.6 km/h and distances of 65 kilometres without rest
* Diving: in shallow waters, up to 2 minutes

Food

* mainly ringed seals, more rarely bearded seals, harp seals and hooded seals
* cadavers of walruses and whales
* occasionally small mammals, birds, fish, herbs, berries, seaweed
* cannibalism (rare): mainly adult males eating cubs
* polar bears can fast for up to 12 months

Hunting behaviour

* pack ice or drift ice is essential for hunting success
* creeping up on seals' birth lairs and breathing holes
* diving underwater to seals' resting places on ice floes
* lying in wait in front of breathing holes or places where seals go to sunbathe
* diving underwater then jumping to catch sea birds (rare)
* attacking walruses and small whales (rare)
* hunting reindeer on land (rare)

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Social Structure

* solitary
* cubs stay with the mother for up to 2.5 years

Sexual Maturity

* male: mature at 5 to 6 years, in the wild able to compete with other males at 8 to 10 years
* female: mature at 4 to 5 years

Reproduction

* mating season between April and June, depending on region
* usually, several males compete for one female ready to conceive

Length of Pregnancy

195 to 265 days
Size of Litter

* twins (70 per cent)
* one cub (25 to 30 per cent)
* very rarely triplets or quadruplets

Interval Between Litters

* at least 3 years (if previous cubs were reared successfully)
* 1 year (if previous cubs were lost)

Birth Weight

500 to 700 grams, 900 grams in exceptional cases
Birth Den

* pregnant females dig a snow den in late autumn
* the birth den usually consists of a tunnel (1 to 3 metres' length, rarely up to 6 metres) and basin (about 2 to 3 square metres)
* usually on land, near the coast (in so-called "denning areas")
* in some regions also on perennial pack ice (drift ice)

Development of Cubs

* the cubs are helpless, blind and deaf when born, with very thin fur
* rapid development with polar bear milk (about 30 per cent fat content at first)
* open their eyes at the end of the first month
* during the second month, first teeth break through
* in the second month, the cubs can hear
* in the third month they stand securely on all fours
* at 3 to 5 months, they leave the birth den
* after leaving the birth den, they take solid foods for the first time
* in the fourth month, the milk teeth are complete
* at about 8 to 10 months, the cubs can hunt their first prey
* weaning at 2 to 2.5 years (rarely earlier, e.g. at 1.3 years)
* the cubs leave the mother after weaning

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Life Expectancy

* 20 to 35 years in the wild
* in zoos, polar bears have lived up to 43 years

Stock

* 20,000 to 25,000 animals in about 20 populations
* status "vulnerable" on the IUCN Red List

Natural Enemies

* none, apart from man
* young and weak animals are sometimes threatened by other polar bears and wolves

Threats

* global warming (pack ice melting, less hunting time)
* pollution of oceans (poisonous chemicals, crude oil)
* over-fishing (less food for the seals)
* disturbances due to mining of raw materials, military use, shipping, tourism
* commercial hunts (in some populations)
* illegal trading of polar bear products (e.g. gall bladders)

Protection

* International Agreement on Protection of Polar Bears (1976)
* regional hunting bans

Collated by Mathias Orgeldinger