Polar Bear FAQs

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What are polar bears?
When did polar bears evolve?
Where do polar bears live?
Are polar bears endangered?
How many polar bears are there?
What is the polar bear's scientific classification and name?
How big are polar bears?
How do polar bears survive in the arctic environment?
What do polar bears eat?
What is the polar bear's place in the food chain?
What is a polar bear's life span?
How many cubs do female bears have?
When and where are the cubs born?
What do newborn cubs look like?
When does the family emerge from the den?
How long do the cubs remain with their mother?
Do polar bears hibernate?
Are there different populations of polar bears?
Does the polar bear have any predators?

What are polar bears?
The polar bear, Ursus maritimus, or the sea bear, is the only bear classified as a marine mammal. Polar bears top the food chain in the Arctic, where they feed primarily on seals. They reach these seals from a platform of sea ice.

When did polar bears evolve?
The fossil record for polar bears is sparse, but ongoing genetic studies are providing new insights on polar bear evolution. Recent studies suggest that polar bears split from a common brown bear ancestor 350,000-6 million years ago. Unlike their brown bear cousins, which live on land, polar bears are superbly adapted for survival on the frozen seas of the Far North.

Where do polar bears live?
Polar bears are found across the Arctic. They are most abundant in areas with annual sea ice and productive ringed seal populations. There are five nations with polar bears: U.S. (Alaska), Canada, Russia, Greenland (Kingdom of Denmark), and Norway (Svalbard). Polar bears do not live in Antarctica. Penguins do.

Are polar bears endangered?
Polar bears are listed under a variety of classifications depending on international, national, and regional regulations. Internationally, they are listed as a vulnerable species by the IUCN. In Russia, polar bears are classified as a Red Data Book species, a listing that includes animals considered rare or endangered. In the U.S., polar bears are listed as a threatened species under the Endangered Species Act. Canada considers polar bears a species of special concern under the National Species at Risk Act. On a regional level in Canada, polar bears are listed as threatened in both Manitoba and Ontario under provincial endangered species legislation.

In all cases, the primary conservation concern for polar bears is habitat loss and reduced access to their seal prey due to climate change. Scientists predict that as the Arctic continues to warm, two-thirds of the world's polar bears could disappear within this century. Research also shows that hope remains if action is taken to greatly reduce greenhouse gas emissions soon.

While rapid loss of sea ice is the primary threat to the polar bear’s long-term survival, other challenges include pollution, increased commercial use of the Arctic, overharvest, disease, and inadequate habitat protection (denning and seasonal resting areas).

At the 2014 meeting of the PBSG, the world's leading polar bear scientists reported that of the 19 subpopulations of polar bears, three were declining, six were stable, and one was increasing. They lacked sufficient data on the status of the remaining nine.

How many polar bears are there?
Scientists can only provide informed estimates. In 2008, scientists estimated that there might be 20,000 to 25,000 of them.

What is the polar bear's scientific classification and name?
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Ursidae
Genus: Ursus
Species: Ursus maritimus (sea bear)

A polar bear's closest relative is the brown bear, Ursus arctos.

How big are polar bears?
Very big! Adult males normally weigh 350 to more than 600 kilograms (775 to more than 1,300 pounds). Adult females are smaller, normally weighing 150 to 295 kilograms (330 to 650 pounds). Researchers in Canada estimated one male bear at 800 kilograms (1,700 pounds)!

Scientists usually refer to how tall bears are by measuring them at the shoulder when on all fours. Those heights are typically 3.5-5 feet for adult polar bears. An adult male may reach over 10 feet when standing on its hind legs.

How do polar bears survive in the arctic environment?
They're built for it! Polar bears are designed for the arctic climate, where winter temperatures can plunge to -45º C (-50º F). Polar bears are insulated by two layers of fur that help keep them warm. When in good body condition, they also have a thick fat layer. In addition, their compact ears and small tail also prevent heat loss. In fact, polar bears have more problems with overheating than they do from the cold—especially when they run.

Polar bear feet are furred and covered with small bumps called papillae to keep them from slipping on ice. Their sense of smell is powerful for detecting seals. And their powerful claws can haul out a 40-90 kg (150-200 lb) seal from the water for dinner.

What do polar bears eat?
Polar bears have evolved to feed on ice seals, specifically seal fat, the highest calorie food source possible. The bears prey on both ringed and bearded seals across their range, but will take other prey when available. Ringed seals, which are smaller, are the most accessible, especially to younger bears and females. Male polar bears also hunt bearded seals, which are much larger. When an adult bear is in good shape, polar bears eat only the blubber in order to build up the fat reserves they need to sustain themselves between meals. They leave the carcass for scavengers, such as arctic foxes, ravens, and other bears.

All the other foods that polar bears may eat are less predictable. Most of these foods, with the exception of walrus or whales, don't provide enough calories to sustain the polar bear's massive body size or to build up the bear's own fat reserves.

What is the polar bear's place in the food chain?
Right at the top of the arctic food chain. Polar bears balance nature by preventing an overpopulation of seals.

What is a polar bear's life span?
While short by our standards, polar bears are considered long-lived animals. In the wild, polar bears live an average 15 to 18 years, although biologists have tagged a few bears in their early 30s. In captivity, some long-lived bears reach their mid- to late 30s. Debby, a captive bear in Canada, lived to be 42.

How many cubs do female bears have?
Twins
are most common, but they can have singlets or triplets depending on the mother's body condition. They give birth to their first litter when they are between four and eight years old—most frequently at five or six. Polar bears have the one of the slowest reproductive rates of any mammal, typically producing only five litters in their lifetime.

When and where are the cubs born?
In November or December in snow caves called maternity dens. After feeding heavily in April or May, females that have mated dig a den in late October or early November. Most choose den sites in snowdrifts along mountain slopes or hills near the shore. Some dig their dens in snowdrifts on the sea ice.

What do newborn cubs look like?
Like a big, white rat. At birth, cubs are 30 to 35 centimeters (12 to 14 inches) long and weigh little more than half a kilogram (about one pound). They are blind, toothless, and covered with short, soft fur. They are completely dependent on their mother for warmth and food.

When does the family emerge from the den?
In March or April. During her time in the den, the mother does not eat, drink, or pass waste. Cubs grow rapidly, thanks to the calories in their mother's rich milk, which is about 31% fat. In their first year of life, cubs are called COYs, which stands for cubs of the year.

How long do the cubs remain with their mother?
Until they're about 2.5 years old. Some bears in the Hudson Bay area historically weaned their young at age 1.5, but this behavior has become rare. During their time with mom, cubs learn how to hunt and survive in one of the earth's most challenging environments. Between the time when they leave their mother and when they are mature enough to mate, polar bears are called sub-adults.

Do polar bears hibernate?
Pregnant female polar bears dig a snow den, give birth, and emerge three months later. During this time, they live off their fat reserves. But they don't hibernate in the strict sense of the word. True hibernators experience a marked drop in heart rate and body temperature and generally stay for a longer period within a den. Adult males and non-pregnant females don't den up at all.

Are there different populations of polar bears?
Yes. Scientists and managers recognize 19 distinct subpopulations of polar bears, but no subspecies. These 19 subpopulations were created for management purposes and do not necessarily reflect ecologically meaningful separations. More recent research based on both habitat and genetics suggest there are four primary groups of polar bears: ice divergent, ice convergent, seasonal ice, and archipelago.

Does the polar bear have any predators?
Only humans, and on rare occasions, other polar bears. Some scientists hypothesize that food stress is increasing acts of cannibalism, which has historically been a natural, but infrequent event.

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