Polar bears are among the most fascinating, lovable, and recognizable animals on the planet. They are also one of the largest species of bears. An adult male, also known as a boar, weighs between 775 pounds and 1,400 pounds (351 to 635 kg). Females, known as sows, will weigh 330-650 lbs. (50-295 kg). According to Polar Bear International, the largest known polar bear weighed in at a massive 2,209 pounds (1,000 kg). That’s more than the weight of 11 men who weigh 200 pounds each!
Normally an adult polar bear weighs from 750 to 1450 lbs i.e. 340 to 658 kg. The average polar bear weight ranges from 849 to 904 lbs i.e. 385 to 410 kg. Polar bears living around the Beaufort Sea have an average weight of around 992 lb i.e. 450 kg. Polar Bears feed on a high caloric diet, mostly on the seals’ fat which is the primary reason for their heavyweight. Kodiak Bears are the only bear species that are a little heavier than polar bears on average.
The average male polar bear weighs between 772 and 1543 pounds (350 – 700 kgs). The average female polar bear weighs between 331 to 551 pounds (150 – 250 kgs). Even though it is the sister species to the brown bear, it has evolved and adapted to a narrower ecological environment with many of its body characteristics made for cold weather. A great example of this is the fat deposits, large furry feet with short, sharp, stocky claws for walking on ice and hunting seals in icy open water.
Gender Differences In Weight
The polar bear is amongst the most dimorphic animals in the marine world as the contrasts between the male and female species go beyond having different sexual organs. These differences can include size, weight, color, behaviors, and so on.
Fully grown male polar bears weigh anywhere between 772 and 1543 pounds (350 – 700 kgs). However, on average, the weight ranges between 849 and 904 pounds (385 – 410 kgs) with those around the Beaufort Sea weighing 992 pounds (450 kgs). Most male polar bears, also known as boars, attain this weight by the time they are ten years old. The heaviest male polar bear on record weighed 2209 pounds (1002 kgs).
Female polar bears are referred to as sows. Unlike their male counterparts, they weigh a lot less, about half the boars’ weight, around 331 to 551 pounds (150 – 250 kgs). The heaviest sows ever get is 573 pounds (260 kgs); however, this is extremely rare.
Surprisingly, during pregnancy, sows can put on a lot of weight rivaling their male counterparts. They can weigh up to 1,102 pounds (500 kgs), almost double their body weight.
Sows become sexually mature by the age of six, and soon after, they start gaining weight because of pregnancy. However, the extra weight is not because of the cubs but because of the extra fat deposits they store. This is because they can go months without eating and must have these fat deposits to help them through this period. They only leave the den during the spring.
How Big Is A Baby Polar Bear?
A baby polar bear is about 30cm (12 inches) long when it is first born. Pregnant female polar bears will create maternity dens where they will enter a hibernation-like state for 8 months during which time they will not eat, drink, urinate, or defecate4.
The cubs are born in December/January. The mother will remain in the den with the mother for the first few months. They grow very quickly and are able to begin walking at two months old.
Size Of Polar Bears Vs Other Bears
Polar Bear Size vs Grizzly Bear
On average, polar bears are bigger than brown bears. The main sub-population of brown bear found in North America, the grizzly bear, will typically weigh between 150-350kg (adult male). This is smaller than an adult male polar bear which weighs 350-680kg (775-1500lbs) on average.
Polar Bear Size vs Kodiak Bear
The Kodiak bear is another sub-population of brown bears, found in coastal Alaska and Kodiak Island. These bears weigh around 357kg so can rival some of the smaller polar bears in weight13. However, on average, a polar bear is still bigger.According to the Guinness World Records, a Kodiak bear is usually shorter in length than a polar bear but more robustly built.
Polar Bear Size vs Black bear
An average male American black bear is smaller than a polar bear with a weight between 59 – 300 kg compared to a male polar bear which will usually weigh 350-680kg (775-1500lbs) on average.
How Much Do Polar Bears Weigh At Birth?
Born in snow dens in November or December, polar bear cubs are tiny when they are born, weighing in at just over one pound. However, they grow quickly. A newborn cub will become fully grown at age two. They have a life expectancy of 10 to 15 years.
Weight Changes Through Different Life Stages
The weight of any living organism changes as it goes through life, and a polar bear is no exception as it grows older and matures, its weight increases. After mating in April or May, the fertilized egg remains suspended and doesn’t start developing until August or September. It’s in these four months that sows eat copious amounts of food doubling in weight.
In the wild, polar bear cubs weigh anywhere between 1 and 2 pounds (0.5 – 1 kg) and are born anywhere between November and February; however, those born in captivity might be delivered early. Each litter averagely has two cubs, and even at birth, sows are smaller than boars. Despite females putting on so much weight during pregnancy, cubs are born lightweight. These extra weight deposits help sows produce fat-rich milk. This diet helps them rapidly add weight to about 25 to 35 pounds (11 – 16 kgs) in three to four months. For the next two weeks, the whole bear family can leave the den but don’t venture too far.
Once the cubs are used to walking, they can begin walking to the sea ice so that sows can start hunting again because they can fast anywhere between 7 and 8 months. When cubs are one year old, they weigh about 200 to 350 pounds (90 – 163 kgs), and by the time they are two years old, boars already weigh about 400 pounds (181 kgs) and are even already taller than their mothers.
How Much Do Polar Bears Eat
Polar bears are the top hunters in their Arctic habitat. They can eat 10 to 20 percent of their entire body weight because they have a giant stomach and their body can use about 97 percent of the fat they eat. Polar bears need fat to survive and can eat more than four pounds of it every day. But they can’t go to the refrigerator and pull out a snack the way you do, and sometimes there isn’t any food to eat for months! That’s why they eat so much of it when it’s available. Their body stores it, like a savings account, so they can use it when they need it but can’t find a meal.
Once a seal is captured, a polar bear bites it several times on the head and neck to disable it before dragging it several meters from the water to feed. A polar bear eats the skin and blubber first, then the meat. Polar bears often stop to wash during feeding, using water nearby or rubbing in the snow. Polar bears don’t always eat the entire kill. Carcass remains are scavenged by other bears, arctic foxes, and gulls.
A polar bear’s stomach can hold an estimated 15% to 20% of its body weight. A polar bear generally eats this much only when its energy demands are high. A bear can assimilate 84% of the protein and 97% of the fat it eats. Polar bears need an average of 2 kg (4.4 lb.) of fat per day to obtain enough energy to survive. A ringed seal weighing 55 kg (121 lb.) could provide up to eight days of energy for a polar bear. Hibernating polar bears do not eat.
How The Bears Hunt Seals.
In fall, a seal cuts 10 to 15 breathing holes (known as aglus by Canadian Inuit) in the ice, using the sharp claws on its fore flippers. Seals keep their breathing holes open all winter long, even in ice up to 2 m (6 ft) thick. They surface about every 5 to 15 minutes at one of the holes or use air pockets trapped under the ice when available. Polar bears attack by waiting for seals to breathe at the openings. They locate them with their powerful sense of smell and wait for the seals to emerge. Polar bears have to be smart and patient because the wait can be long—sometimes hours, or even days. Bears also stalk ringed seals that are basking on ice by taking advantage of their sleep-wake rhythms. The bear crawls slowly forward and freezes in place when the animal raises its head. At about 6 m (20 ft) from the seal, the bear uses its explosive speed to pounce, killing the seal before it can escape back into the sea.
Size And Appearance
Polar bears are usually 3.5 to 5 feet (1 to 1.5 meters) tall at the shoulder on all fours, but an adult male may reach more than 10 feet (3 m) when standing on its hind legs, according to Polar Bears International. In 1960, a polar bear that was killed in Alaska stood 12 feet (3.7 m) tall on its hind legs, according to the National Wildlife Federation.
Male polar bears usually weigh between 770 pounds and more than 1,300 pounds (350 to 600 kilograms). The 12-foot-tall Alaskan bear shot in 1960 is the heaviest recorded bear and weighed 2,210 pounds (1,000 kg). Females weigh half as much as their male counterparts, at 330 to 650 pounds (150 to 295 kg), according to Polar Bears International.
Could Polar Bears Switch To Eating Other Foods?
Polar bears have evolved to prey on seals. But they are curious and will eat other foods when available — including geese, bird eggs, whales that wash up on the beach, and even the occasional small mammal. All of these foods are less predictable, however. And most of them, except whales or walruses, don’t provide enough calories to sustain the polar bear’s massive body size or build up the bear’s fat reserves. While individual bears may benefit from eating these foods, they would not provide enough calories, in the right form, to sustain polar bears at the population level.
What’s On The Polar Bear Menu?
Polar bears are carnivores, which means they eat mostly meat. One of their favorite meals is a seal, and especially their fat But though you may only like one or two kinds of pizza, polar bears aren’t too picky about what kind of seals they snack on. Their favorite seals are ringed and bearded seals, but some of the other types of seals they eat are:
One seal can give the polar bear several days of the energy they need. However, seals aren’t the only animals on the polar bear’s menu. If seals become scarce, polar bears will use their keen sense of smell to find carcasses, which are the dead bodies of animals, up to 20 miles away. Some of the carcasses that the polar bear may find and eat include:
What Do Polar Bears Eat?
Polar bears have evolved to prey on ringed and bearded seals, which they catch from a platform of sea ice. Polar bears depend on the high-fat content that seals provide, but will take other prey when available.
Where Do Polar Bears Live?
Polar bears live on the ice-covered waters of the Arctic and countries around the Arctic Circle, including Canada, Alaska in the U.S., Greenland (part of Denmark), Norway, Russia and occasionally Iceland, according to the International Union for Conservation of Nature (IUCN). They are not found in Antarctica, where penguins live.
Some polar bears stay on permanently frozen sea ice in the Arctic Basin, but most live on the annual sea ice that forms around the Arctic Basin. This annual sea ice melts in the summer, so polar bears are forced to spend several months on land while they wait for it to freeze over again, according to the IUCN.
Polar bears swim between sea ice and the shore, hunting down prey, searching for mates, or just cooling off. They paddle through the water with their big front paws and use their back legs as rudders, according to Sea World. They also have webbing between their toes, similar to ducks’ feet, which helps them swim.
Polar bears have been recorded swimming for nearly 10 days at a time and traveling up to 427 miles (687 kilometers) in a single swim without stopping to rest, Live Science previously reported. Long swims like this put polar bears at risk of drowning, but they may be forced to undertake such great journeys more often as warming temperatures associated with climate change melt sea ice in the Arctic.
Are Polar Bears Dangerous To Humans?
Polar bears rarely attack humans. A 2017 study published in the journal Wildlife Society Bulletin cataloged 73 confirmed polar bear attacks between 1870 and 2014, including 20 fatalities. The researchers found that nutritionally stressed male bears were most likely to attack humans and that most attacks were predatory, meaning the bear was killing for food.