A Year in the Life of a Hudson Bay Polar Bear

The largest bear in the world and the Arctic’s top predator, polar bears are a majestic symbol of endurance. The polar bear can be found wandering the Arctic in Canada, America, Russia, Norway and Greenland. Its Latin name, Ursus maritimus, means “sea bear,” which makes sense for a beast that spends much of its life in, around or on the ocean, predominantly on the sea ice. 

There are six distinct polar bear populations along the polar basin’s southern rim, each influenced by a different pattern of ice movement: the Canadian Arctic, Northern Alaska, Western Alaska and Wrangell Island, Svalbard and Franz Josef Land, Central Siberia, and Greenland.

A separate group of bears lives near Hudson Bay in Canada; this is the most southerly population and one we love to visit on our Nat Hab trips. The yearly cycles of freezing and melting ice greatly influence where these polar bears reside and when. Unfortunately, increasing temperatures from climate change are forcing the bears to shift their natural annual cycle, with less time available each year to spend hunting for seals on top of frozen sea ice.

A polar bear’s range is massive, and during the course of a year, one bear may travel more than 20,000 square miles within a general region—but that type of migration requires a strong supply of nourishment. What are they doing as they cover that much ground? How do they fuel up for the journey? And how is climate change affecting that natural cycle?

Let’s get to know these magnificent creatures that the Arctic’s Indigenous Inupiaq call the Nanuuq and learn a bit more about a year in the life of a typical Hudson Bay polar bear. 

Winter

Pregnant female polar bears often spend the winter hibernating, gestating, giving birth to and nursing their new cubs so that they’re strong enough to exit the den in the spring. The snow den protects the defenseless newborns from the frigid cold, and they stay inside it until late March or April. 

Female polar bears give birth every two to three years and have around five litters during their lifetime—one of the lowest mammalian reproductive rates. 

Males and non-pregnant females do not hibernate, instead spending the winter out on the ice surviving off their fat reserves after gorging on seals in the autumn. Their fur and four inches of blubber protect them from the harsh cold, and the thick sea ice provides a solid platform from which they can continue to hunt seals. The soles of their giant (up to 12 inches in diameter) paws act as wide snowshoes and are covered with dense pads of fur that offer great traction on the ice.

Because of their large stomachs, polar bears can devour up to 150 pounds in one sitting, which helps them take full advantage of any food found. They have to consume at least one seal every five or six days to preserve their body weight. The polar bear’s fur is water-repellent and made of unique hollow hairs that permit the channeling of solar energy directly to the polar bear’s black skin underneath, helping them stay warm. This allows the polar bear to survive in the Arctic, where temperatures typically fall to -22˚F during the winter.

Spring

By spring, new cubs usually weigh about 20–25 pounds and are getting ready to leave the den. Playtime in the spring is an ideal way for the little cubs to practice the skills they will need to survive, such as hunting, fighting and communicating with other bears.

During the long months of denning, pregnant and nursing females may not eat for up to eight months, all while having to meet the enormous energy demands of gestation and lactation. Suffice it to say they leave the den hungry!

Meanwhile, big chunks of ice called “floes” carry the male polar bears toward the shore in spring, where they emerge onto land to breed (and look for any remaining food). A female polar bear mates for the first time when she is around five or six years old. Breeding occurs on the ice pack between late March and mid-July. Females go into estrus for roughly three weeks, at which time the males compete fiercely to pursue them. Dominant males may succeed in mating with several females in a season, but they only stick around for about a week after mating.

When a female polar bear becomes pregnant, the embryo divides a number of times, then interestingly pauses its development and free-floats until it finally implants into the uterine lining later in September. 

In later spring, as summer approaches, the bears start a long journey northward, trekking 800 to 900 miles along the coast to seal-hunting grounds. On land, these bears have a chance at scavenging food: a whale, seal or fish carcass washed up on shore or the remains of an animal hunted by another predator. They walk along the western shore until reaching the northwestern coast once again, where they will wait patiently for the ice to freeze. 

Summer

Polar bears in the Canadian Arctic will often choose to summer on the coast to look for food instead of heading north with the retreating ice. During the summer in Hudson Bay, bears meander inland and try to deal with the warm temperatures by sheltering in dugouts deep enough to reach permafrost. They seem to like to stay near the coast, but they have been found up to 100 miles inland in the summer months. 

In the warm summer months, the usually 100% carnivorous polar bears will scarf down pretty much anything edible, including eggs, reindeer, carrion and even plants and berries. Even with this range of foods, polar bears drastically drop weight in summer and early autumn, subsisting primarily on stockpiled fat. They are simply too massive to receive much energy from small morsels like Arctic hare or fish.

Female polar bears reach a maximum weight of approximately 660 pounds, with males coming in on average from 1,100 to 1,300 pounds. The largest recorded polar bear weighed a whopping 2,210 pounds—not an easy figure to maintain in the summer on paltry berries and eggs. And as the seal-hunting season continues to shorten in a warming Arctic (ice is freezing much later in the year and melting much earlier), hungry polar bears may struggle to retain enough fat stores to survive through the long summer seal fast. 

Autumn

Around October, the planet’s largest concentration of polar bears gathers along Hudson Bay, waiting for the ice to form so their seal-hunting season can begin. By mid-October, between 600 and 1,000 bears congregate along a 100-mile stretch of coast between the Churchill and Nelson rivers (with an abundance around Cape Churchill).

When the ice finally becomes thick enough to withstand their weight, the bears eagerly head out onto the frozen sea to prey upon seals. Polar bears feed mainly on ringed seals, but they also hunt bearded, harp and hooded seals, as well as the occasional walrus. Polar bears have excellent eyesight and hearing, and their noses are so sensitive that they can detect a seal more than 20 miles away. In fact, researchers in Alaska have watched male polar bears travel very focused in a straight line for up to 40 miles to reach prey they’ve detected.

Using their jagged back teeth and canines larger than those of a grizzly, polar bears eat the fat and skin of their prey and leave the meat for Arctic foxes, with whom they share a mutualistic symbiotic relationship.

Pregnant females construct their maternity dens in deep snow drifts on land in autumn. A soon-to-be mom has to ensure the snow is deep enough for her and her cubs, yet stable enough that it won’t cave in on top of her. In the past, many female polar bears built dens on the sea ice, but the warming climate has made it difficult to find quality places to den on the ice, so bears have increasingly been making dens on land on coastal and river bluffs, barrier islands and other areas where snow accumulates. Cubs are born blind between November and early January and weigh only about 1.5 pounds at birth.

Polar Bears: Under Threat

Because of the ongoing loss of their sea ice habitat from increasing temperatures, polar bears were listed as a threatened species in the U.S. under the Endangered Species Act in May of 2008. The survival of polar bears and the protection of their habitat are urgent issues for both us at Nat Hab and our partners at World Wildlife Fund.

As climate change forces polar bears to spend more time onshore, they come in contact more often with Arctic communities, which all too often ends badly for either the humans or the bears (or both). In Russia, Alaska, Greenland and Canada, WWF has responded to human-bear conflict with a variety of community-led initiatives. WWF and its partners are also working to catalyze the development of new technologies that will make polar bear research more cost-effective, less invasive and deliver more useful data to help support their protection. 

What’s the Best Time of Year to See Polar Bears in the Wild?

By far one of the best places to view polar bears in the wild is along Hudson Bay’s western shore in the autumn. Hudson Bay is a huge body of water, about double the size of Texas, that covers 850 miles from north to south and 650 miles east to west. Polar bears congregate near the shore here as they wait for Hudson Bay to freeze, when they rush onto the ice to hunt and fatten up as much as they can before winter, meaning at this time they are relatively active and out and about. 

Just two polar bear tour operators in Churchill hold highly coveted permits to access the full Churchill Wildlife Management Area—where the best polar bear viewing occurs—and we are proud to claim one of them. With this, not only are we able to provide our travelers with the best wildlife-viewing experience, but we are able to travel in comfortable custom-built Polar Rovers that can navigate the tundra and the remote Hudson Bay shoreline to give us access to prime bear viewing. 

What’s more, because of our close partnership with WWF, Nat Hab and our Arctic Expedition Leaders have access to the latest research and information on polar bear habitat and conservation initiatives—which benefits both the bears and our guests!

Ready to meet the King of the Arctic for yourself? Consider joining us on a Churchill Polar Bears trip soon!