Scientists studying polar bears encountered the most unexpected surprise during a recent tracking expedition in northeastern Manitoba.
In mid-November, a polar bear mother and her cub were walking near Churchill, and scientists saw her with a second cub, which they confirmed was not her own. This marks the 13th such cub adoption in the western Hudson Bay subpopulation.
“When we confirmed this was an adoption, I had mixed emotions, but mostly good ones,” Alyssa McCall, director of conservation outreach and scientist at Polar Bears International, said in a video provided to the media.
“It’s just another reason why this species is so incredible and so fascinating and interesting, and it gives you a lot of hope when you realize that polar bears are probably out there taking care of each other.”
Dr. Evan Richardson, a polar bear research scientist with Environment and Climate Change Canada, came to the field back in March. His research team discovered the mother in the cave area of Wapusk National Park, south of Churchill.
When the photo was taken in November, two of the bears were wearing GPS tracking collars, but the new bear was not. (Photo by Dave Sanford)
In a separate video provided to the media, Richardson said that during that sighting, there was only one cub with the mother.
Fast forward to the fall, and Richardson was surprised to see a family of two turn into a family of three. Two of the bears had previously been tagged with GPS tracking collars, but the newly adopted cub was not.
“But it’s not that common because in our long-term study we have over 4,600 bears known over the past 45 years, and there are literally hundreds of dens. [of cubs],” he said of the adoption.
Evan Richardson, a polar bear research scientist with Environment and Climate Change Canada, suspects that strong maternal instincts led the mother bear to adopt the lonely cub. (Submitted by Samantha Bayard)
Researchers estimate the mother is about 5 years old and the cubs are 10 to 11 months old.
Richardson isn’t sure why the mother adopted the lonely, roaming cub, but he has a hypothesis.
“We really think it’s just because [polar bears are] Such motherly mothers, such good mothers, they couldn’t let a cub cry on the tundra. So they pick them up and take them with them,” he said.
After being found with just one cub in March, the female polar bear was found with two cubs in November after adopting a polar bear that roamed alone. (Photo by Dave Sanford)
Polar bear cubs typically stay with their mother for two to two and a half years.
“It’s not a lot of time to learn how to be a polar bear, but they do learn a lot of lessons during that time. The cub’s survival rate as an adult is about 50 percent … but if we know a cub doesn’t have a mother, it has almost no chance,” McCall said.
The adopted cubs now have a good chance of reaching adulthood, she said.
It’s unclear what happened to the adopted cubs’ biological mothers, but Richardson hopes the samples of genetic data his team obtained from the cubs will provide some insight.
The National Weather Service partners with Polar Bears International and the University of Alberta’s Polar Bear Science Program to collect data on polar bears through GPS collars. The movements of tagged bears can also be tracked online.
McCall said female polar bears in the western Hudson Bay region have been collared for decades, but only about 10 bears are collared each year.
It’s not common for polar bear cubs to be adopted, and it’s even rarer to see one in person.
“Bears need all the help they can get today with climate change,” Richardson said. “The female has a chance to pick up another cub and care for it and successfully wean it off. That’s a good thing for Churchill’s bears.”