Polar Bear Fact File
Ursus maritimus
Credit: Public Domain
Weight
150-800kg
(330-1760lbs)
Length
2-3m
(6.6-10ft)
Lifespan
Wild 18 years
Captive 30 years
Diet
Carnivore
Seals
Conservation Status
IUCN
Vulnerable
Polar bears are tied with brown bears as the world's largest land-based carnivore with mature males weighing up to 800kg (1760lbs) and measuring 3m (10ft) long.
They are carnivores with a range of adaptations to allow them to eat foods such as seals and beluga whales. Large amounts of food are eaten during summer to make-up for the lack of available food in winter or to allow the females to spend winter tending to their cubs.
Every two years a female can produce a litter of cubs which following a period of intense feeding she will give birth to in a den. They remain there through the period of inactivity over winter before emerging in summer to begin feeding.
These bears have become a symbol for conservation with the species increasingly threatened by climate change which is causing the sea ice they rely on to melt.
Read on to learn more about these marvellous mammals.
Appearance
What does the polar bear look like?
Polar bears have a more elongated body shape than the brown bear and have a longer skull and nose. They have stocky legs and a small tail and ears.
They have very large feet, an adaptation to help them when walking on the snow and ice and which also act like big paddles when they are swimming. Their front paws are partially webbed to help with this. The pads of the feet are covered with small bumps which provide extra grip on the ice. They also have short, strong claws which help them to grip prey and also help with digging in the ice. The feet of an adult polar bear can measure 30 cm (12 in) across.
Their neck is longer than other bear to help them leap at prey.
Polar bears have 42 teeth due to the fact that they have a carnivorous diet.
The polar bear is covered in a thick undercoat of fur protected by an outer coat of long guard hairs. These guard hairs stick together when they are wet and providing a waterproof barrier to help keep them dry. It appears as though they have white fur but that is not the case, the hair is actually transparent hollow tubes filled with air. The skin underneath the fur is black which helps them to soak up warmth from the sun.
Their snow white coloration is an adaptation which helps them to blend in with their habitat.
They are insulated by a layer of blubber that is between 5 to 10cm thick (2 to 4 in) that helps them stay warm in the cold water or freezing air. It can also be used to sustain them if they are unable to find food for a period of time.
A short tail of 8-13cm (3.75-5in) long is present at the end of the body.
The length of the average polar bear is 2-3m (6.6-10 ft) long with the average weight for a male being between 300 and 800 kilograms (660-1760 pounds). Females are smaller at between 150 and 300 kilograms (330- 660 pounds). Both males and females stand 1.7m (5.6ft) tall at the shoulder.
Brown bears and polar bears are the two largest land-based carnivores though debate is ongoing as to which is the largest.
Diet
What does the polar bear eat?
The polar bear is a carnivore. The main part of their diet is pinnipeds such as the ringed and bearded seal. Birds, fish and larger mammals such as walrus and belugas are also consumed.
Beached whales, grass, seaweed, plants and berries are rare additions to the diet.
They prey on the seals when they come up from holes in the ice to breathe or come out to rest. The polar bear has an extremely developed sense of smell and will wait by the hole and be able to smell when the seals breath is close to the surface, they will reach into the hole and drag the seal out.
The polar bear bites the seal on the head to crush its skull to kill it. They will sometimes hunt a seal on the ice by crouching quietly behind it and then rushing forward to pounce on the seal. Another way that they can get seals is to raid the birth areas that seals have created in the snow.
Adult polar bears will eat the skin and blubber of the seal first and then eat the rest of it.
Credit: Public Domain
Range
Where can you find the polar bear?
Polar bears are found in the ice-covered waters of the arctic in Europe and Asia. Here they can be found in the following countries - Canada; Greenland; Norway; Russia; Svalbard and Jan Mayen and in the state of Alaska in the United States.
Vagrant individuals will occasionally be seen in Iceland.
Habitat
What kind of environment does the polar bear live in?
Their preferred habitat is artic, tundra and woodlands. They like to stay on the sea ice packs all year round if they can because this keeps them in close contact with their main food source the seal. When the summer comes and the ice packs start to melt the polar bears will travel miles to stay on the ice.
If the polar bear is forced to remain on land for a while because the ice has melted they will survive on their fat reserves until the ice forms again.
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Reproduction
How does the polar bear produce its young?
Polar bears mate between April and May. Once the polar bear has mated the female is able to keep the fertilized egg in a suspended state until August or September. This allows her to be able to eat a lot of food to build up her fat deposits to live on while she is in the maternity den or until conditions are right. Once she implants the egg gestation is 195-265 days.
Females which are able to develop larger fat reserves will produce larger cubs and typically have higher rates of success in raising their cubs.
Once the female becomes pregnant she will make a maternity den in the snow with a narrow entrance tunnel leading to one to three chambers. In the den the female will enter a state that is similar to hibernation, however it does not involve continuous sleeping she will just slow her heart rate down.
The female will give birth to 1-3 cubs with 2 being typical. The cubs are born blind and helpless. They are covered with light downy fur and weigh 0.6kg (1.3lbs) on average.
The cubs will stay with the mother in the den for the next 3-4 months drinking their mothers milk which is very rich in fat. The mother will then break open the entrance to the den. At this time the cubs will weigh between 10 and 15 kg (22 to 33 lbs).
Cubs remain with the mother close to the den for awhile to let them get used to walking on the ice etc, then they will walk to the ice packs so the mother can resume feeding herself.
Young will try out solid food for the first time at 5 months old but continue to nurse and receive protection from their mother for two years.
Sexual maturity is reached between 5 and 6 years old.
Behavior
What does the polar bear do with its day?
Polar bear adults usually live solitary lives but they can sometimes be seen playing together. Young male polar bears especially like to play fight and this might be used as practice for when they may have to fight during the mating season.
Polar bears communicate using a wide variety of sounds including purrs, roars, bellows and growls.
When the temperature gets really cold they may make a den in the snow and sleep. They do not hibernate as other bears do but they are able to slow down their bodily functions such as their heart beat. This allows them to conserve their energy and live off their fat deposits until they are able to hunt again.
Females raising cubs may go up to 8 months without eating. This is believed to be the longest period of starvation undertaken by any mammal.
These animals are capable swimmers and spend much of their time in the water. They can reach speeds of up to 10kmh (6mph).
Their body is covered by air filled guard hairs which assist with buoyancy. The nostrils close while the bear is under the water.
Credit: Public Domain
Predators and Threats
What is impacting the survival of the polar bear?
Polar bears can be dangerous to humans especially if they are hungry but if they are able to get food they will usually only attack humans if they are provoked however they are extremely unpredictable.
The low population densities and remote habitats of the polar bear mean developing a clear estimate of their population difficult.
These animals have been facing a wide range of threats. One of the largest is climate change which is causing dramatic changes to the sea ice on which they rely to feed.
Another threat is the increase of pollutants in their food chain. As an apex predator this has a large effect on the polar bear. It is unclear exactly how this will affect polar bears but levels are now high enough to cause life-long health effects. This can also be passed through milk from mothers to their young.
Human activity including the presence of icebreakers and drilling for oil affect polar bears. This is increasing with tourism also becoming increasingly popular in their habitats.
In parts of their range the polar bear is managed for subsistence hunting. They may be used for meat, clothing and handicraft.
Quick facts
Polar bears spend most of their time in the water.
They have an extremely powerful sense of smell, and can smell a seal on the ice up to 32 km (20 miles) away and can smell a seals den that has been covered with snow.
Polar bears can see really well under the water, and can see a meal about 4.6m (15ft) away.
It is believed that polar bears go through a molting period where they will lose some of their fur, but this happens not to replace their whole coat but to regulate their body temperature when the weather starts to get warmer.
Credit: Public Domain
References
Jackson, T. and Chinery, M., 2012. The illustrated encyclopedia of animals of the world. London: Southwater.Burnie, D., 2011. Animal. 3rd ed. London: DK
Ambrose, J., 2015. Wildlife Of The World. 1st ed. London: Dorling Kindersley
Wiig, Ø., Amstrup, S., Atwood, T., Laidre, K., Lunn, N., Obbard, M., Regehr, E. & Thiemann, G. 2015. Ursus maritimus. The IUCN Red List of Threatened Species 2015: e.T22823A14871490. https://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T22823A14871490.en. Downloaded on 21 May 2020.
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