Rare Footage Shows Baby Polar Bears Emerging From Their Den in the Arctic

At birth, polar bears are blind, nearly hairless and weigh just over a pound—about the same as a loaf of bread. But they spend their first few months snuggled inside a snowy den, fattening up on their mother’s milk. By the time they emerge in the spring, the cubs are covered in fluffy white fur and weigh 22 to 26 pounds.

But because polar bears (Ursus maritimus) make their dens in frigid, hard-to-reach places, researchers know very little about this vulnerable stage of their lives. Now, however, scientists have managed to capture rare footage of a polar bear mother and her cubs leaving their den in the Arctic for the first time.

The video comes from Svalbard, the sparsely populated archipelago located between mainland Norway and the North Pole. Taken using a remote camera, the footage shows a mother polar bear walking across the snowy landscape—followed, one after another, by her three cubs. The juveniles appear to slip and slide as they try to catch up with their mom.

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Researchers captured the heartwarming video from one of 13 den sites they monitor on Svalbard. The cameras are helping scientists learn more about polar bears’ mysterious denning behavior, and they outline some of these insights in a new paper published Thursday in the Journal of Wildlife Management.

“In Svalbard, polar bears build their dens on the slopes of steep mountainous areas, and it’s hard to imagine how cubs could find their feet in this severe terrain,” says study lead author Louise Archer, an ecologist with the University of Toronto Scarborough and the nonprofit conservation group Polar Bears International, to Live Science’s Sascha Pare. “Watching them sliding, tumbling and even climbing up on their mother was truly remarkable.”

Pregnant female polar bears typically build their dens in snow drifts on land or sea ice around October or November. They give birth in December or early January, then spend the next three to four months fasting while nursing their cubs. In the spring, usually around April, the entire family emerges.

“The snow-covered den is almost like an extension of the womb—it provides a warm and stable environment, allowing cubs to continue to grow and develop,” says Archer, who collaborated with researchers from the San Diego Zoo Wildlife Alliance and the Norwegian Polar Institute for the study, to BBC Wildlife magazine’s Graeme Green.

The new study combines the remote video footage of the Svalbard den sites with data from GPS tracking collars affixed to each mother bear. The findings suggest polar bear families might be leaving their Svalbard dens earlier in the spring than they have in years past. However, researchers caution that they need to conduct further monitoring to fully understand whether this is a continuing trend.

In addition, researchers also learned that polar bears emerged from their dens periodically throughout the winter. Some left for less than a minute before returning, while others spent several hours away. Cubs rarely left their dens without their mothers, heading out on their own just 5 percent of the time.

Two polar bear mothers were even observed moving into new dens, which raises new questions for future studies to attempt to answer.

“Why did she move?” Archer says to IFLScience’s Rachael Funnell. “What were the conditions in the original den that caused her to move elsewhere? What are the consequences of this for the polar bears and for their cubs?”

When the bears abandoned their dens in the spring, they typically stayed close to them for a while—but that period ranged widely from family to family, spanning from two days to as long as a month. Eventually, they ventured off toward the sea ice, where the mothers could nab seals—and start to teach the little ones how to hunt.

“Some of the things that really struck me were just how much variation we saw in behavior between the different polar bear families,” Archer tells Science’s Gennaro Tomma. “This is important because it means there is not a one-size-fits-all approach for protecting denning habitats and migration paths during important times of the year.”

New Study: Polar Bear Cubs Emerging From Maternal Dens

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The study’s sample size was small, which means the findings may not necessarily apply to all polar bears, says Andrew Derocher, an ecologist at the University of Alberta in Canada who was not involved with the research, to Science.

But since researchers know so little about polar bear denning, even a small glimpse into this previously hidden period could prove useful for conservation. Polar bears face numerous threats to survival, from climate change to pollution and disease. Human activities—including drilling for oil and gas—can inadvertently disturb the dens and harm the bears. Plus, both mothers and cubs are at their most vulnerable during this denning period.

“Populations require healthy cubs to ensure the survival of the next generation—this really starts with giving bears the best chance during these first few months in the den,” Archer tells BBC Wildlife magazine.

Sarah Kuta | READ MORE

Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.