Polar bear

The polar bear (Ursus maritimus Pipps, 1774) is the world’s largest land-going predator. It lives in coastal areas and on sea ice throughout the Arctic region. The polar bear is therefore considered a marine mammal. It thrives best in nutrient-rich shallow waters where sea currents flow and the ice does not become too thick in winter. Seals are the polar bear’s main source of food, on which it relies for its survival. Polar bears can travel long distances in search of food, and they are often found at sea on drift ice. Their southernmost range is determined by how far the winter ice reaches. The polar bear’s scientific name (Ursus = bear, maritimus = maritime) acknowledges its close relationship with the ocean, where it lives most of its life. In Icelandic, the polar bear is known as hvítabjörn (‘white bear’) or ísbjörn (‘ice bear’).

Hvítabjörn
Picture: Daníel Bergmann

A polar bear.

A bear’s life

The polar bear is a symbol of the Arctic, and with good reason. The animal is extremely well adapted to life in the far north. The polar bear travels across vast regions in hunt of food, keeps in step with seasonal fluctuations in sea ice and heads for locations where seals gather to breed and forage. Polar bears have thus adapted to stay in sync with the seasonal habits and behaviours of seals.

Unlike other bear species, polar bears generally do not hibernate. Pregnant females, who give birth in dens, are an important exception, although they do not hibernate in the strict sense of the word as the heart rate does not drop and they do not go into torpor. The long distances that a polar bear must travel to hunt would make establishing and defending a territory of its own impossible. However, breeding females do have a tendency to remain within the same area, often choosing to den at the same sites again and again. Polar bears are not social animals, but several bears can sometimes be spotted together at locations where food can be found, such as seal haul-outs or spots where the sea ice is thin, making it easy for seals to surface in order to breathe and dry off.

The polar bear’s size is an asset in the Arctic. They are able to accumulate enormous energy stores in the form of body fat, which helps them in times when food is in short supply. Their body fat also insulates them from the cold. Underneath their skin is a layer of fat that can reach up to 11 cm in thickness. The low-density fat provides buoyancy and thus helps bears to stay afloat and makes swimming easier. In water, their fur becomes wet to the skin, but their underfur keeps the water temperature immediately next to their skin constant and acts as insulation.

Reproduction

Polar bears reach sexual maturity at the age of 3–4 and can have offspring into their twenties. Males (boars) compete with each other for the favour of receptive females, and fighting can be fierce. The largest and strongest males succeed in mating with the most females. Mating takes place in March–April, but the foetus does not begin to develop until the year’s end. Female polar bears (sows) care exclusively for their young.

A pregnant female needs to fatten herself all summer and fall. In December, she digs herself into a snowdrift, and she remains there in a hibernation-like state for the next 2–3 months. The gestation period lasts around two months. Her cubs are born in midwinter. Newborns are blind, without protective guard hair and weighing less than a kilo each. There are generally two cubs to a litter. A female sometimes gives birth to only one cub, but litters of three cubs are extremely rare. Cubs live with their mother in and around her den until spring, by which time they have reached around 10 kg. By this point, the mother has not eaten for up to six months and has depleted most of her energy store. She leads her cubs to the sea to hunt. She avoids other polar bears, particularly while her cubs are still young. Cubs accompany their mother for the next two years, learning from her how to hunt and to fend for themselves.

A female polar bear becomes receptive again around two years after she has given birth to her litter. At this point, her cubs must provide for themselves and steer clear of confrontations with older and stronger polar bears. Females reach sexual maturity at a slightly younger age than males, but only two of every three females will be receptive in a given year. The others are raising their cubs.

Polar bears in Iceland

Polar bears are not native to Iceland, although they do occasionally turn up in Iceland and are thus classified as vagrants. Information exists on just over 600 polar bears recorded as having arrived in Iceland from the beginning of human settlement on the island to the present day. This is a somewhat imprecise figure, since polar bears have undoubtedly come ashore without their presence going noticed, while bear sightings and encounters were not always documented in the past. The last polar bear observation was at Hvalsnes in North Iceland in July 2016.

Sea ice is a major factor in determining when and where polar bears come to Iceland. The overall distribution of polar bear observations on land is in keeping with the distribution of sea ice around Iceland. Most polar bear observations are from the north and northeast of Iceland.

Dreifing hvítabjarna sem sést hafa á Íslandi

Distribution of polar bear sightings in Iceland. Points show the number of observations.

Upplýsingar um komur hvítabjarna frá landnámi

Observations of polar bears in Iceland from the ninth century to the present. Columns show the number of animals.

The actual frequency at which polar bears arrive to Iceland can only be assessed with any accuracy for the last 2–3 centuries. On average, polar bears have been observed every other year for the period from 1951 to the present day. The overwhelming majority of observations took place in the nineteenth century, when bears were spotted 2–3 times a year on average. From the middle of the eighteenth century to the present, only 1–2 bears were seen together at a given time. During the first half of the eighteenth century, the average was over five animals for each sighting. Polar bears can be safely assumed to have been just as common in previous centuries, but more accurate information does not exist.

Response to polar bear arrivals in Iceland

Visits by five polar bears in 2008 (two bears), 2010, 2011 and 2016 gained wide attention both in Iceland and abroad. A debate arose over the validity of killing vagrants belonging to a species in danger of extinction. At the same time, it is clear that polar bears will never thrive in Iceland in the long term due to the lack of sea ice here and the limited food supply. Conditions in Iceland are furthermore such that females would be unable to give birth and raise offspring here.  

After the polar bear visits in 2008, Iceland’s Minister of the Environment appointed a task force to make recommendations on how authorities should respond in the event of a polar bear coming to shore in Iceland. The committee reached the conclusion that the most appropriate way would be to kill vagrant bears in Iceland. Three main grounds were cited for doing so. Firstly, the safety of humans and livestock is at issue, since polar bears are a danger to both. Secondly, it is known that vagrants in Iceland come from the population in East Greenland, which can well withstand the occasional bear being shot here in Iceland. Thirdly, any rescue attempt would involve unjustifiably high costs.

The task force also recommended that a response team be appointed to deal with polar bears in Iceland, with representatives from the National Commissioner of the Icelandic Police, the Environmental Agency of Iceland, the Icelandic Institute of Natural History, the Icelandic Food and Veterinary Authority and sharpshooters.

Effects of climate change

Climate change and associated warming in recent decades has already started to have a visible impact on the Arctic. The glaciers are melting, and their surface area and coverage are shrinking. The sea ice has grown thinner, and some areas freeze over only in deep winter. Polar bears are affected by these changes, and the negative impact of warming on bear populations and their viability has already been demonstrated.

The International Union for Conservation of Nature (IUCN) has a specialist group that monitors polar bears closely. At issue are 20 populations, which are not genetically isolated because the bears are highly mobile. The specialist group tracks the bears’ movements, body condition and reproduction. The main challenge facing bear populations is disruption to their habitat due to sea ice changes, which affect feeding conditions and reproductive success. At the same time, pollution caused by persistent pollutants and heavy metals that accumulate at the top level of the food chain have begun to have an effect on their body condition, survival and reproductive success. If ice cover retreats or becomes too weak to allow polar bears to roam as widely as they do today, then it is likely that populations will become isolated as a result of hindrances to gene flow.

Conservation status

Under Act no. 64/1994 on the protection, conservation and hunting of birds and wild mammals, the polar bear is a protected species in Iceland, except when it poses a threat to people and farm animals in Iceland. The killing of polar bears at sea is expressly forbidden, irrespective of whether they are swimming or floating on sea ice.

The states governing the territories, in which polar bears’ habitat is found, work collectively towards polar bear conservation on the grounds of an agreement signed in Oslo in 1973. The agreement’s objective is to protect the polar bear and its habitat, as well as to ensure the sustainable utilisation of polar bear populations. Member states exchange knowledge and collaborate in conservation efforts, together with research, monitoring and management. In Greenland, legislation was passed in 2005 that bans disruption of the bears’ mating season and protects females with cubs. Hunting quotas for Greenland were established at the same time.

In 2006, the International Union for Conservation of Nature (IUCN) classified the polar bear as a vulnerable (VU) species on a global scale. The Polar Bear Specialist Group of the IUCN (PBSG) predicts that the global population size will be reduced by 30% over the next 45 years due to climate change and environmental toxins. The polar bear is also classified as a vulnerable species in Greenland and Svalbard.

The polar bear has been assessed for the Red List for Mammals. Since the polar bear is a vagrant in Iceland rather than a resident, it does not qualify for assessment for Iceland’s Red List for Mammals. The polar bear is classified as a vulnerable species at both the European regional level and the global level.

  • Heimildir

    Heimildir

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