All About the World's Largest Bear Species


group of polar bears on beach - all about the worlds largest bear species

Wondering what the largest bear species in the world is? It’s not as easy an answer as you might think. Some people give the title of “World’s Largest Bear Species” to the Kodiak bear (Ursus arctos middendorffi) and some to the polar bear (Ursus maritimus). The Library of Congress says the debate has arisen because it’s hard to pin down what we mean by “largest.” “The answer,” they say, “really depends on how ‘largest’ is definedHeaviest? Longest? Largest ever recorded?”

Their ultimate choice is the polar bear. To back up their choice, they turn to the Great Bear Almanac, written by now-retired National Park Service ranger and bear management expert Gary Brown. Brown puts the average weight of the male polar bear (the larger sex of the species) at 900-1500 pounds and the heaviest bear recorded as being 2,210 pounds. The average length of a mature male polar bear, according to Brown, is 8-8.4 feet. Standing on their hind legs, they can reach over 10 feet tall, according to the North American Bear Center.

The Alaska Department of Fish and Game, on the other hand, champions the Kodiak bear. They state that males (again, the larger sex of the species) can also be over 10 feet tall standing up and weigh up to 1,500 pounds. The North American Bear Center (which also chooses the polar bear for world’s largest bear species), cites a journal that discusses one wild Kodiak bear who reached 1,648 pounds. The very heaviest Kodiak bear, they tell us, was in captivity at the Dakota Zoo, and weighed 2130 pounds on his death.

Given how close in size these two species are, it does not seem surprising that people favouring one species or the other could find evidence to support their choice. In either case, these bears are enormous. But that’s only the start of what’s interesting about these two amazing giant species.

Polar Bears

Polar bears are found throughout the Arctic regions of the globe. They’re technically not land mammals—as their scientific name (Ursus maritimus) suggests, they’re considered marine animals. They spend much of their time out on the sea ice. It's only from the ice that they can hunt their primary source of food, seals. The time they can spend on the ice, however, is shrinking due to climate change.

Unlike southern bears, polar bears only find dens to hole up in for winter when they’re pregnant. Females who give birth will curl up sometime in the fall and stay cozy for 4-5 months until the babies become more mobile. Polar bears usually give birth to 2 or 3 cubs, who will stay with their mothers for about 2 years.

Non-pregnant bears weather out the winter because this is the season when sea ice gives them the best access to seals, walrus and other foods like whale carcasses. When sea ice retreats for the warmer seasons, they’ll move onto the tundra, which is generally the start of a fasting period.

They can go without eating for up to eight months, says conservationist group Oceana, but that fasting period is stretching to, and even past, the limit in some locations because global warming has increased the number of days bears need to spend on land.

They can eat other food, like bird eggs, small mammals and seaweed, but their bodies require a lot of calories and are specialized to take in fat, which makes seal hunting necessary for their survival. This makes them highly vulnerable to climate change. Without sea ice to hunt from, they could literally die out from starvation because nothing on land has enough fat to keep them going.

Incredible Facts About Polar Bears

They’re technically not white, although they appear that way. Polar Bears International explains that their hair is actually transparent. It doesn’t have any pigment, but it does have “a hollow core that scatters and reflects visible light.”

They don’t need to drink water. As it’s digested, the fat in their diets provides them with enough hydration that they never need to drink.

They have interesting and sophisticated social lives. Although they’re usually solitary animals, they share food when food is abundant (like when they come across a whale carcass), as long as other bears ask first. Polar Bears International says they will “ask permission” to share food with other bears by touching noses.

They can live up to 32 years, according to the North American Bear Centre, although the average lifespan is 15-18 years.

Kodiak Bears

kodiak bear by water - all about the worlds largest bear species

Kodiak bears are a species apart, quite literally. They’re only found on the Kodiak Archipelago, which is off the southwest coast of Alaska. Like the polar bear, their yearly movements are driven by food, and during warmer months, they roam the islands in pursuit of sustenance.

While some males of the species might stay awake all winter, the majority of bears go down for hibernation starting typically in late October, according to the Alaska Department of Fish and Game. They start emerging in late spring.

Pregnant females will bed down longer, sometimes waiting until the early summer before bringing their cubs out into the world. Like polar bears, Kodiak bears usually give birth to 2-3 cubs, but these cubs stay with their mother for 3 years.

The Alaska Department of Fish and Game explains that although these bears are often given the additional title of world’s biggest land carnivore, that’s not true. They’re omnivores. “They actually spend more time eating grass, plants and berries than meat,” says wildlife biologist Larry Van Daele. Few bears, he says, “expend the time or effort necessary to chase and kill mammals.”

Bears eat a lot, and Van Daele tells us that they’re especially good at focusing on “the most nutritious parts of their food to maximize their weight gain.” They’ll pursue particular foods when those foods are at their peak nutritional value, and when they get them, they’ll eat the most nutrient-dense parts.

Kodiak bears follow a yearly pattern of pursuing spawning salmon in the summer, berries in late summer and salmon again in the fall. William Deacy’s research on Kodiak bears revealed that even when salmon are abundant, bears will leave off fishing to focus on eating elderberries, which tells us that they’re interested not just in consuming calories, but consuming the right kinds of nutrients to maximize their weight gain.

Deacy’s observations, however, are tied to a larger phenomenon than just bears showing a preference for particular foods. The convergence of elderberry season and salmon spawning season is a recent development brought on by climate change. Elderberry season used to come after salmon season, but increasingly overlaps it, which Deacy notes forces “bears to choose between the foods.”

What nobody knows is how that choice will impact the rest of this island ecosystem. Deacy explains that the islands, which are largely undeveloped, are biodiverse enough that Kodiak bears can shift their foraging patterns to take advantage of other, later spawning salmon when the elderberries are gone.

Other plant and animal species who rely on the far-reaching “carcass distribution” that bears provide during the earlier spawning season, or who rely on bears not catching the later-spawning salmon they’ve historically eaten less of, will be impacted in unpredictable ways.

Incredible Facts About Kodiak Bears

They can consume “as many as 20,000 calories per day from eating berries,” says wildlife biologist Robin Barefield.

They can sleep for 5-8 months per year without losing any muscle. Barefield also explains that unlike other animals who rest for long periods (including humans), Kodiak bears don’t lose bone mass or muscle function during hibernation and scientists do not know how this happens yet.

They “put themselves into a diabetic state while in hibernation and then reverse out of it in spring” so their fat stores don’t break down too quickly over the winter, according to Barefield, whose blog is a treasure trove of amazing information.

The longest living Kodiak bear in the wild was 34 years old, according to Bear Conservation. Average lifespan, however, is 20-25 years.

One Final Incredible Fact About Bears in General

They purr. And it is adorable.

By Anne Elliot

Feature image: Dick Hoskins; Image credit: Brent Jones