A Polar Bear Year
The great white bears that walk the land and sea ice of northeastern Alaska and northwestern Canada make up the southern Beaufort Sea subpopulation of polar bears in the circumpolar North. Indigenous peoples have lived here for thousands of years with Nanuuq, the Inupiaq name for the polar bear; traditional knowledge holds great respect for the bear, in part for its clever adaptations to hunting and living on both sea and land and surviving in difficult conditions.
The behavior and biology of the Beaufort Sea bears inspired the following story of a year in the life of a female polar bear along the coast of Arctic National Wildlife Refuge.
Three polar bears sleep curled together on a small barrier island in the southern Beaufort Sea, on the northern edge of Arctic National Wildlife Refuge. The two young cubs nestle into their mother’s side, blocking their faces from the autumn wind. Their coats, once bright, are spotted with brown from their time spent resting on land.
Back in early summer, the family had sniffed out many seal lairs and eaten well. The mother, whose fat reserves had been dangerously low after denning all winter with her cubs, nearly doubled her weight after leaving the den. The high fat content of the seal pups was also perfect nourishment for the two growing cubs. The cubs now weigh as much as arctic wolves — though they are much stouter. Even now, late in the fall, all three bears still have a healthy layer of blubber to keep them warm.
But this year’s seal pups are all grown up. They are strong swimmers, and no longer need to stay near the sea ice. Seals prefer to forage in the shallow waters close to the coast where the fish and crustaceans they eat are more plentiful. Polar bears hunt by using ice as a platform from which to ambush seals, but by autumn the sea ice is far from the shallow waters where seals are found.
When the climate was cooler just a few decades ago, sea ice was usually visible from Alaska’s northeastern coast all year long. Polar bears in this region could swim between land and ice, and hunt seals throughout much of the year. These days, the summer thaw comes earlier, and the winter freeze up comes later, giving the sea ice more time to melt. The polar bear’s icy habitat shrinks as the Arctic warms. In recent years, the autumn sea ice is a floating island hundreds of miles from the coast, in the center of the Arctic Ocean where seals are rare.
Most polar bears spend autumn on the remaining sea ice, waiting for cooler temperatures to expand the ice back over the seal’s preferred habitat. However, more bears than ever before are staying on Alaska’s coast through the fall. 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.
This polar bear family has come to shore for the season. This particular part of the shoreline is where winter’s land-fast ice will form first. Still, it could be weeks until the ice freezes solid enough to allow the mother to hunt. And so, they spend their time relaxing on gravel islands or the tundra. The cubs sometimes roughhouse together or play with sticks and seaweed clumps. But for most of the day the family snoozes, conserving energy.
The mother rests her massive head on one cub’s fuzzy back. Suddenly, her eyes pop open. She lifts her long nose, sniffing the cold breeze for a moment. The next instant she is on her feet. The cubs blink at her. The mother huffs quietly at them. It is time to get moving.
The mother treks along energetically, only pausing to check that her cubs are close. She marches into the frigid lagoon separating the Alaskan coast from the little island on which they had been resting. Polar bears are considered marine mammals because they are specially adapted to live in the ice-covered waters of the Arctic. They are excellent swimmers: their giant, slightly webbed paws work like paddles, and their nostrils close underwater. Adults have the fur, blubber, and strength to swim for miles, but cubs get cold and tired more easily. Polar bear mothers make sure not to swim too far with their cubs.
Today’s swim is a quick one, and soon the cubs are walking on the tundra, shaking water from their fur. The mother continues her march and the cubs lope after her on shorter legs.
They walk and sometimes swim their way west until they reach what the mother had been searching for: the remains of a bowhead whale. The carcass is almost 40 feet long from head to tail.
For thousands of years, Inupiat communities have lived on the Arctic coast, hunting whales as their primary source of food. In the villages, whale remains are brought to the edge of town after the community has taken the parts they need. Now that melting sea ice has caused more polar bears to stay on land in autumn, the bears are drawn to coastal whaling communities. If polar bears could hunt seals at this time of year, they would likely not be very interested in whale carcasses. But until the sea ice re-forms, whale remains provide an energy-rich food source for hungry bears.
The mother and her cubs are not the only ones who can smell a whale carcass from miles away. She chuffs quietly to her little ones as she investigates the scene, and they come close to her sides. She spots another polar bear mother with a cub near the whale’s giant ribs, and a young adult female near the head. She approaches the whale slowly, her eyes locked on the other bears. They watch her carefully, but do not stop gnawing meat from the bones.
When the family reaches the enormous whale, the mother starts licking the remains, looking for chunks to pull off. The cubs copy their mother’s technique.
For a long time, they work on the carcass, getting what scraps they can from the bony remains. The moon is already hanging low in the sky when the wind shifts. The mother abruptly stops feasting to sniff deeply, pointing her nose east along the coast. In the distance, a white dot glows against the dark tundra. Another polar bear is approaching.
The mother tenses. Even from a distance, she can smell that this bear is an adult male. Male polar bears have been known to attack polar bear cubs. Though it may seem gruesome, they may do this when they are very hungry. Until the ice returns and makes seal hunting possible, there is almost nothing to eat. To a hungry male, a cub could be a welcome meal.
The mother bear turns back toward the carcass and digs her teeth into a particularly large chunk, bracing her legs against the bone. With a mighty tug, she yanks the meat off the carcass. Still holding this last morsel, she growls to her cubs through clenched jaws. At this sound, the cubs cease their gnawing and follow their mother as she retreats quickly from the male.
Without slowing her pace, the mother frequently glances over her shoulder to ensure that her cubs are close — and to track the male’s movements. The lone female from before has moved to the opposite end of the whale but is still working on the bones as she watches the newcomer carefully. He pays her no mind as he starts exploring the carcass. The other mother and her cub are long gone. They too had decided not to wait and find out whether this male would be peaceful.
Now that she sees that the male is not in pursuit, she slows her pace enough that her cubs can keep up easily. Darkness falls as the moon dips below the horizon. Mother and cubs walk together onto the tundra under a sky of autumn stars.
Story by Katherine Monroe, USFWS.
In Alaska we are shared stewards of world renowned natural resources and our nation’s last true wild places. Our hope is that each generation has the opportunity to live with, live from, discover and enjoy the wildness of this awe-inspiring land and the people who love and depend on it.