Polar bears (aka the white bear and ice bear) are one of the most amazing and fascinating animals on the planet.
These large animals are known for their ability to survive in some of the coldest and harshest places on earth, such as Arctic.
From an evolutionary stand point polar bears are believed to have branched off from their ancestors, the brown bears, approximately 2.6 million years ago during the Pleistocene era, which lasted until around 12,000 years ago with the oldest known polar bear fossil records dating back 130,000 – 110,000 years ago.
Today, scientists estimate that there are roughly 20,000 to 25,000 polar bears left on Earth, but their existence is being threatened by a number of factors such as pollution, climate change, oil exploration and excessive hunting.
This article will explore the physical characteristics of polar bears, their diet and hunting methods, social structure and the threats they face from humans and the earth.
Physical Characteristics and Appearance
When it comes to size and weight polar bears a quite tremendous.
A fully grown male polar bear may weight between 750 – 1,550 lbs. with an average weight of around 850 – 950 lbs.
Females generally weigh around half the amount of their male counterparts, however during pregnancy a female polar bear may double in weight and actually outweigh a male polar bear.
In terms of height males may reach lengths of 7.10 – 9.10 ft. tall while females measuring between 6 – 7.10 ft. tall.
Polar bears are instantly recognizable due to their white fur, but their fur is actually not even white!
It is really transparent and pigment-free, but the hollow core reflects and scatters light, giving off a white appearance in sunlight.
This white appearance can make polar bears difficult to spot in the snow and may help them when they are hunting for prey or trying to avoid detection.
At other times of the year, especially before molting, polar bears can actually look yellow, and they may appear green when algae grows in their hair shafts.
In order to survive in these cold climates polar bears have a thick layer of blubber, which can measure up to 4 inches thick in order to help the polar bear stay warm in freezing temperatures.
The thick layer of blubber acts as a strong insulator and helps keep the vital organs from freezing, especially when diving underwater.
In addition to their thick layer of blubber they also posses a thick coat of fur (as mentioned earlier) that helps prevent wind from making contact with their skin and helps keep heat close to their body.
Under their fur, polar bears have black skin.
When it comes to moving and navigating through the cold Arctic environment they are born in polar bears have large paws that enable them to walk on land comfortable and easily.
In fact their paws can grow as big as one foot across, which makes them perfect for treading on thin ice and roaming the Arctic.
While they tend to pace the snow at around 3 – 4 mph they can reach speeds of up to 25 mph for short bursts.
Polar bears’ paws are also ideal for swimming because they act as large paddles.
In fact in rare instances a polar bear can swim continuously for hundreds of miles when traveling from one location to the next using its blubber for buoyancy and its large paws to propel itself through the water.
One polar bear has even been observed swimming for nine days in order to reach a piece sea ice in the Arctic Ocean.
Like the rest of their skin, their footpads are also black.
Papillae, or small bumps, cover the paw pads and help the bears grip the ice and prevent slipping.
At the ends of the footpads are thick curved claws that can grow over two inches long.
While the polar bear does have large paws its tail is one of the shortest among the various bear species.
To capture prey polar bears have 42 teeth with large, sharp canine teeth designed for biting, grabbing and tearing.
Using their strong arms and powerful jaws these large bears are able to capture their prey quite effectively and defend themselves against most attacks.
Diet and Hunting Methods
Given their cold habitat polar bears are known for consuming various sources of meat, which is the primary source of food in their region.
The majority of a polar bear’s diet consists of seal meat.
Both ringed and bearded seals are prey.
Because seals are marine mammals they must surface for oxygen and will often rest on land and when they do they risk becoming prey to lurking polar bears making themselves an easy target when swimming or resting in isolated areas.
From time to time polar bears will hunt local walruses when they are hungry and other food sources are not available.
Polar bears are also known to consume the carcasses of deceased whales such as the beluga whale, bowhead whale and narwhal.
On rare instances polar bears have been observed climbing almost vertical cliffs in order to capture birds and their eggs.
In fact the polar bear is considered one of the largest land carnivores in the world and rightfully so.
Their Arctic habitat doesn’t always allow them to consume other forms of food such as plants, however they may find vegetation on certain parts of land, especially during the warmer summer months.
While these marine mammals live on land they primarily hunt in and around the ocean where their food is known to live and may spend a good majority of their time inhibiting their ocean surroundings.
Most hunting takes place where the land and water meet and although polar bears are great swimmers their odds of capturing prey in open water is much lower than when they hunt where the land and water meet as its easiest to capture prey that is trying to surface and/or obtain oxygen near land.
To capture prey polar bears are known to use several hunting methods which may include raiding, stalking and still-hunting.
Raiding
Raiding typically involves a polar bear locating the birth lair/cave of a female seal where she is hiding and nurturing her young.
If the polar bear identifies a seal in the lair it will slowly rise up and slam down on the lair in order to break the ice and hopefully capture its prey.
If the polar bear doesn’t get through the thick ice quick enough it may allow the seal time to escape.
Stalking
Stalking occurs when a seal or group of seals decides to rest on the ices surface.
Once spotted by the polar bear the bear will move in slowly and quietly in order to camouflage itself from the resting seals.
After getting within 100 – 50 ft. of the seals the polar bear will then attempt to run and chase down the seals in order to make a capture.
Stalking may also occur when a polar bear is swimming underwater near the ices surface.
The bear will try and swim silently to avoid detection and once near the edge of the ice it will try to leap out and catch any seals close to the edge.
Still Hunting
The third and most common technique used by polar bears is known as still-hunting.
Still hunting involves a polar bear crouching and waiting near a seals breathing hole or lead edge where the seal must come up for air.
Once the seal rises to the surface to get some air the polar bear will grab the seal, haul it onto the ice and crush its head in order to kill it.
During hunting season the polar bears will only eat the blubber of their prey in order to create fat reserves that will later sustain their bodies between meals.
The seal carcasses are left for other animals, like younger bears, ravens or arctic foxes.
During certain times of the year and under certain conditions the polar bear can survive for up to 8 months without eating any food.
This typically occurs when the seasons change and their prey begins to migrate away from the polar bears local grounds.
In other instances polar bears may migrate along with their prey in order to keep feeding.
When locating prey these marine mammals rely largely on their excellent sense of smell as they are capable of detecting seals from nearly a mile away.
In addition to their sense of smell they also have decent hearing and are able to spot objects from a long distance.
A recent concern regarding the diets of polar bears suggests that these marine mammals may suffer from consuming polluted/poisoned meat which can lead to severe sickness and death.
While rare starving polar bears may result to cannibalism and have been observed eating the carcasses of other polar bears.
Habitat, Migration and Survival
When it comes to habitat and survival the polar bear is one of the toughest animals alive.
These large bears are able to survive in temperatures of minus 70 degrees for extended periods of time.
There are 19 distinct populations of polar bears on the planet, spread throughout areas in the circumpolar north, including Alaska, Canada, Greenland, Norway and Russia.
Often classified as marine mammals, polar bears spend most of the year at sea, however their large size and physical characteristics give them an advantage over other marine mammals as they are able to travel many miles on land and can travel a far distance from the ocean, a characteristic that is uncommon among other marine mammal species.
Polar bears often prefer to live on the sea ice that covers the continental shelf’s waters and the archipelagos of the Arctic.
To stay close to their main source of food, seals, polar bears frequent areas where the water meets sea ice.
As the weather changes throughout the year, polar bears may migrate further onto land in search of other food sources.
Contrary to what most people think polar bears aren’t as aggressive as they are often made out to be.
In fact they tend to be fairly cautious when it comes to direct confrontations.
They also appear be non territorial as a species.
Polar bears that have been recently fed rarely attack humans unless provoked or threatened, however polar bears that are hungry and haven’t eaten in a while may be quite dangerous and unpredictable in nature and are known to occasionally attack, kill and even eat people as a result.
What can be said about polar bear attacks on humans is that when they do occur they are often predatory attacks and usually fatal, and even if a polar bear appears well fed and non aggressive it should not be approached under any circumstances.
Reproduction and Breeding
During mating periods male polar bears are known to fight one another for the right to mate with a female.
Aggressive fighting may lead to scars and broken teeth among competing males.
Once a male polar bear gains the right to mate with a female polar bear he may spend the week with the female mating several times during that week in order to maximize her chances of becoming pregnant.
In most cases polar bears appear have polyganous relationships where a male may have more than one female partner, however observations have shown that in some instances female polar bears may also give birth to cubs of different fathers.
Polar bears mate from late March through early May.
Pregnant females feed heavily during their pregnancy and may double their body weight as the feed and prepare to give birth.
During this time the female polar bear may also dig a den in October or November to prepare for birth around December.
The den sites are often along hills or mountain slopes near the shore, but some bears create dens on the sea ice in snowdrifts.
Polar bears may give birth to a single offspring or twin cubs and in some cases they may even produce triplets.
During their lifetime, most polar bears only produce around five litters.
Polar bears reach sexual maturity between the ages of six and ten, at which point they may begin baring offspring of their own.
Social Structure and Communications
Polar bears are primarily solitary creatures that do not live in groups, however they are known to form relationships with one another and may spend hours playing, cuddling together and sleeping as they hold one another.
Twin cubs also tend to partner together for a period following weaning, often hunting and playing together, but they will eventually go separate ways.
With that said polar bears do tend to prefer a solitary life style.
Even in zoo settings in which two or more polar bears share a space, they tend to stick to different areas of the habitat.
Vocal communication may include a variety of sounds such as growls, roars and purrs which can vary in tone depending on the situation and what the polar bear intends to communicate to other polar bears in the area.
Physical communication may involve play fighting, biting, cuddling, pawing and during mating periods real fighting which can lead to actual injuries.
Threats, Hunting and Predators
Polar bears are known as apex predators meaning they are able to hunt freely without having to worry about facing threats from other predatory animals.
The most significant threat to polar bears’ survival is the loss of their sea ice habitat caused by climate change.
The amount of time the bears can hunt for prey has decreased due to the shorter ice season, and they are forced to survive the summer without regular feedings.
As a result, many polar bears may face starvation and suffer from malnutrition.
Polar bears are also threatened by increasing human contact as they are forced to spend more time onshore, industrial impacts from the development of certain areas of the Arctic, unsustainable hunting and oil spills caused by offshore petroleum installations.