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Polar Bear Characteristics

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

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)

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

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