Did you know the cute and cuddly bears that appear in Coca-Cola ads are actually apex predators of the Arctic ecosystem? Polar bears spend most of their lives in temperatures that can be as cold as -50 degrees Fahrenheit (-45 degrees Celsius). They roam the Arctic sea ice in search of prey and play a vital role in cleaning up their ecosystem and providing food to scavenger species.
Polar bears are awe-inspiring creatures that are in imminent danger due to the effects of climate change. To help protect them, it’s important to understand and learn about them. In this article, we’ll discuss everything about polar bears and the polar bear populations living in Alaska.
Biology of Polar Bears
Polar bears are specifically adapted to the Arctic, the marine environment they call home. These bears can weigh up to 600 kg (1,300 pounds) and stand 1.6 meters (5.3 feet) while on four legs and up to 2.4 meters (7.8 feet) on their hind legs.
They have two thick layers of fur covering their body that prevent heat loss so well that they can become overheated from short sprints. The hairs are transparent, not white. They look white thanks to the hairs ability to scatter and reflect visible light.
In addition to their fur, polar bears can have a fat layer measuring up to 11.4 cm (4.49 in) thick. The fur keeps them warm when dry, and the fat keeps them warm while they’re in the water.
Polar bears have massive, 30 cm (11.81 in) paws that help them distribute their weight better on ice and act as paddles while swimming. Their footpads give them great traction and help keep them from slipping, while their 5 cm (1.97 in) long claws aid in traction and holding onto their prey.
Polar bears have shortened ears and tails. The smaller size is another way they combat heat loss.
Polar Bears Diet
The bulk of a polar bear’s diet is made up of seals, specifically ringed and bearded seals. Their habits, behaviors, and evolutionary adaptations are all defined by preying on seals. A single bear can eat over 100 pounds (45 kilograms) of blubber at one time.
Starting in the fall, seals will cut 10 to 15 holes in the sea ice to use to breathe. They need to pop up in a hole for a breath every five to fifteen minutes. Polar bears locate these holes and stalk them, waiting for the seals to come up for air.
They’ll patiently wait by a set of holes for hours and even days to snatch a seal. Polar bears are mostly dependent on seals because of the high-calorie fat on the seal’s bodies and the lack of other viable food sources for such large predators.
If they spot a seal basking on the ice, polar bears will stalk them too. They’ll slowly sneak up on the seal and then stop moving when the seal looks their way. Their white coat helps them to hide against the ice. Once within range, they use a short burst of speed to pounce on the seal.
When they aren’t low on food, the bears may only eat the blubber and skin of the seal, leaving the rest of the meat on the ice. This is a vital source of food for scavenger species like ravens, but also allows bears with less luck to have a meal.
While good swimmers, bears can’t match seals performance in the water. The sea ice gives them a platform to catch seals.
Aside from seals, polar bears are known to eat some other foods. These can include geese, eggs, washed-up whales, walruses, and small mammals. For the most part, these are foods of desperation.
While a whale or walrus will provide the necessary calories to sustain a polar bear, the other options do not. These options are also much less predictable and consistently available than seals popping up to breathe.
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Polar Bear Location Range
The home of polar bears is a constantly shifting and ever-changing area of Arctic sea ice. The ice expands in the winter and shrinks in the summer, so vast tracts of freezing-cold ice determine their true range.
Polar bears can be found on the sea ice around countries including the U.S. (Alaska), Canada, Russia, Greenland, and Norway (Svalbard). Scientists have divided them into nineteen populations, some of which stretch across more than one of those countries.
How far an individual bear travels is determined by the quality and quantity of sea ice, as well as the availability of seals for prey. Many bears may limit themselves to within 100 kilometers ( 62. 13 miles), while other bears may go thousands of miles from their original home.
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Polar Bear Life Cycle
Polar bears typically have a lifespan of 15 to 18 years, however, scientists have tagged multiple individuals over the age of thirty. The bears exhibit seasonal behavior, especially in females.
Most of a polar bear’s life is spent hunting on sea ice. It’s the best environment to hunt seals, and they are the undisputed apex predator outside of the water.
Polar bears are usually solitary animals. Mating usually occurs in the spring between April and June. Male polar bears follow the scent and footprints of female bears out on the sea ice. Within a few days of mating taking place, the males leave the females and go off on their own.
The fertile eggs inside the female don’t implant themselves until fall. Whether they implant at all is entirely dependent upon the mother’s fat stores and whether she can sustain herself and her pups through winter. This process is called delayed implantation.
Mother polar bears eat as much as possible through summer and fall to build up fat stores. Before winter closes in, they dig a burrow into a snowdrift just large enough for them to turn around in. The mother then goes inside the den and waits for falling snow to cover the entrance, hiding her inside.
These dens serve as maternity wards for pregnant polar bears. The females give birth to between one and three baby bears and the family stays inside the den until spring. During that time the mother won’t eat, drink, or leave the den.
Cubs are totally dependent on their mothers while young. Newborns are blind, toothless, and only weigh around one pound or half a kilogram. The cubs will continue nursing from the mother for their first 20 months of life.
Cubs learn all of their survival skills from their mothers. They spend the first two-and-a-half to three years of their lives under the watchful eye and protection of their mother.
Polar bears reach adulthood when they’re ready to mate. In females, this is usually between ages 4 to 6 and for males between ages 6 to 10. Adult males typically weigh 350 to 600 kg (775 to 1,300 lb) and adult females typically weigh 150 to 295 kg (330 to 650 lb).
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Polar Bears in Alaska
Two of the nineteen polar bear populations can be found in Alaska, the Southern Beaufort Sea population and the Chukchi Sea population. Their habitat range fluctuates greatly throughout the year, driven by seasonal changes in sea ice. In total, only around 4,700 polar bears inhabit Alaska.
The Southern Beaufort Sea population is found on the northern coast of Alaska, and further east into the Beaufort Sea area of Canada. A 2014 study found this population had dropped from over 2,000 bears to between 1,500 to 900 bears.
The Chukchi Sea population is found on the western end of Alaska, ranging as far west as eastern Siberia and Wrangle Island, as well as far south as the Bering Islands. The status of the population is less well-known than of the Beaufort Sea population, as their range extends further.
Some of the Beaufort Sea polar bears exhibit rare behaviors you typically don’t see with polar bears. In the summer when pack ice recedes, some of them move onto the beaches and rest until the pack ice returns in the fall.
The seasonal distribution of Alaskan polar bears is generally as follows:
- Spring: Females emerge from winter dens on barrier islands or on land. Most bears closely follow the pack ice and hunt for seals from those platforms.
- Summer: Most bears follow the ice as it recedes northward, aside from the few who remain on the northern coastline.
- Fall: Distribution is directly related to ice and seal availability, sometimes coming as far south as the Bering islands when temperatures and food allow it.
- Winter: Females den for the season along the northern coastline, Wrangel Island and other Russian Islands, islands in the Canadian Arctic, Greenland, and Spitsbergen. In winter, males can be found as far south as St. Lawrence Island.
Overall, the status of polar bears in Alaska is on the decline. Lower amounts of sea ice limit their range and hunting grounds. Thinner ice and longer periods without ice contribute most to both populations suffering.
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Polar Bear Management and Hunting In Alaska
Polar bears are incredibly important to the native people of Alaska. Their meat is eaten by people and dog teams and the hides are turned into clothes. Up until 1942, these subsistence hunters were the only people actively hunting polar bears in the region.
Not all of these individual groups and settlements hunt polar bears. While they do make use of the animals, they are not a main target or staple food. Their hunting activities only accounted for around thirty taken bears per year and averaged less than a US quota limit set in place around the year 2016.
The 1959 statehood act which formally made Alaska a state within the United States was the first act that began to manage polar bears from the outside. It took some time both before and after the Statehood Act to gather data and decide what regulations would be put in place for hunting activities. Prior to this, native groups managed themselves, limiting their hunting during leaner years for the bears.
From 1942 up until 1972, sport hunting activities by other groups took place. Worldwide between 1963 and 2016, around 900 bears were killed each year. In Alaska prior to 1972, sport hunters could take one bear each year between 1 January to 30 April. Hunters could not target females with cubs, or cubs themselves.
In 1972, Richard Nixon signed the Marine Mammal Protection Act (MMPA) into law. This prohibited the taking of marine mammals for any reason and put a moratorium of undefined length on the import, export, or sale of marine mammals or derivative products. The act did not outlaw marine mammal harvest by subsistence hunters or native peoples.
The Marine Mammal Protection Act provided protection for polar bears, whales, seals, and all other marine mammals.
The Act defined taking animals as hunting, killing, capturing, and/or harassment of any marine mammal. Harassment was defined as “any act of pursuit, torment or annoyance which has the potential to either: a. injure a marine mammal in the wild, or disturb a marine mammal by causing disruption of behavioral patterns, which includes, but is not limited to, migration, breathing, nursing, breeding, feeding, or sheltering.”
There were exceptions to the Act outside of allowing for the rights of native people. Permits may be issued for scientific research, public display, and the importation/exportation of marine mammal parts.
After the MMPA became law, polar bears could not be hunted for sport. Regulated hunting is prohibited outside of allowances for native peoples, and this continues to be the law even today.
Northern Canada is home to the majority of the world’s polar bear population. A 1973 multilateral Agreement on the Conservation of Polar Bears allows for Inuit hunters and trophy hunters guided by Inuit guides to take up to 600 bears per year. The quota is changed on a yearly basis and determined by scientific data.
These guided hunts, along with a partial lifting of importing products to the US has allowed those communities to bring in much-needed money. In 2008, the US listed polar bears as threatened and that trophy hunting window was closed.
A concerted effort to map out denning areas and protect them is an ongoing process. Oil, gas, and mineral extraction are typically outlawed in these areas, and extra environmental protections are put in place.
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Polar Bear Populations in Alaska National Parks
Two national parks have polar bears within their borders. The range of polar bears extends into the borders of the Bering Land Bridge National Preserve and Cape Krusenstern National Monument. Both parks offer the chance to see these amazing animals in person or through their wildlife cameras.
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What Threats to Polar Bears Exist?
While poaching of bears, drilling activities, and pollution do contribute to the decline of polar bear populations, the largest threat to them by far is climate change.
1 Climate Change
Arctic temperatures are rising twice as fast as the rest of the world, and sea ice cover is declining at a rate of nearly four percent per decade.
Polar bears have specifically adapted to living on sea ice. In fact, they’re almost entirely dependent on it. It provides a place for them to den, a mating ground, and is the primary reason they’re able to hunt the seals they depend on for their food.
While polar bears have shown some ability to adapt their feeding habits and forage on land, these food sources are less sustainable for the bears and will lead to them becoming food-stressed and a population decline.
As the climate warms, even in small amounts, less sea ice forms throughout the year. Thinner ice is a danger to bears as they can fall through it and become trapped. Longer periods of the year where there is less or no sea ice isolate bears and keep them from being able to hunt.
Additionally, warmer temperatures will mean more fragmentation of sea ice. As pieces break up and float apart, bears can become stranded far away from where they started. While they can swim pretty well, polar bears are not true aquatic animals.
Away from sea ice, fewer cubs are able to survive and fewer births happen as females can’t build up proper fat stores. Shorter seasons mean less time to hunt as well, meaning they will go without food for longer periods.
Polar bears’ prey, seals, are less dependent on sea ice. The bears hunt near the edge of the ice pack, moving with it through seasons. The seals don’t necessarily follow that migration pattern.
Warmer weather also leads to weaker and melting snowdrifts. This can cause the collapse of dens and the premature death of polar bear cubs who haven’t seen the outside world yet.
Subsistence hunting, poaching, and trophy hunting are and likely always were at a level that likely wouldn’t wipe out the bears.
Unregulated hunting and weak data to back up yearly quotas do pose a threat to polar bears. In no way is this threat as time-sensitive or daunting as climate change.
Proper counts and accurate numbers of bears are hard to obtain. Polar bears inhabit incredibly remote and harsh environments, making it difficult to gauge population health. As with other species, unbridled hunting could become an issue. This is unlikely though, as demand for polar bear products is low and the cost of hunts is high.
Poaching, while problematic, is not a major threat to most populations of polar bears. The Canadian and American populations are typically well-regulated and protected from most poaching efforts.
Bears on the Russian side of the Bering Strait are the target of poachers more frequently, but not in the huge numbers you would expect. Estimates of illegally killed bears in the region averaged around 200 from 1994 to 2003, but have since dropped off to around 50 to 70 bears per year.
3. Pollution, Extraction, and Exposure
Like other top predators, polar bears are susceptible to high levels of toxins. This is because as chemicals like mercury travel up the food chain, they occur in higher concentrations the farther up you go.
To explain simply, a small fish may contain a milligram of mercury. A larger fish then would eat hundreds of those smaller ones in its lifetime. Seals eat hundreds of those larger fish, and bears eat hundreds of seals. While it is a rather crude explanation, simple math shows the exponential growth of mercury buildup in the food chain.
Other pollutants such as plastics, human waste products, and chemicals can pose threats to the entire Arctic ecosystem, also threatening polar bears.
Alaska holds likely forty percent of the United States’ remaining oil and gas reserves. To get to these, humans need to establish drilling platforms and pipelines. This construction and extraction can result in population fragmentation, destruction of denning areas, and environmental risk.
In the event of a spill, oil can become a major threat to polar bears. When their coat comes into contact with oil, it loses much of it’s insulating effects. This decreases the bear’s ability to stay warm and increases its calorie needs as it compensates. This can make sustaining itself difficult.
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Polar Bear Interactions With Humans
Climate change is one of the reasons more bears are spending summers on land and the main reason many bears have trouble finding enough food. This, along with larger settlements in their natural range has contributed to people and bears coming into contact more frequently.
Polar bears are large, aggressive predators. Unlike brown bears that may maul a person and leave, nearly all polar bear attacks are fatal and predatory. These are incredibly rare due to the small numbers of people in areas with polar bears. There isn’t too much data on interactions because of the rarity.
Polar bears, like other bears, can learn to associate humans with food. When this happens, they’ll likely search through human settlements for food and become a nuisance. Because of the threat they pose, these bears can be legally killed.
A bear that has plenty to eat rarely attacks people unless provoked in some way. Lack of interaction means that many polar bears simply don’t fear people. A hungry bear is unpredictable though and will do whatever it takes to try to survive.
The Alaskan Fish and Wildlife Service encourages people to have a plan in place in the event of a polar bear encounter. You can find more information here regarding typical behaviors, what to look for, deterrents, and what to do if you encounter a bear.