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Scientists studying polar bears were greeted with a most unexpected surprise during a recent expedition to track polar bears in northeastern Manitoba.
In mid-November, a mother polar bear and her cub were walking near Churchill when scientists saw her with a second cub, which they were able to verify was not her own. This is only the 13th adoption of cubs in the western Hudson Bay population.
“When we received confirmation that it was an adoption, I had mixed feelings, but mostly good ones,” said Alice McCall, director of conservation and research fellow at Polar Bears International, in a video provided to media.
“That's another reason why this species is so incredible, why they're so fascinating and interesting, and it gives you a lot of hope when you realize that polar bears may be looking out for each other.”
Dr. Evan Richardson, a polar bear research scientist with Environment and Climate Change Canada, was on the ground back in March. His research team caught up with the mother as she left her den in Wapusk State Park, south of Churchill.
Only one cub was with its mother during the sighting, Richardson said in a separate video provided to media.
Fast forward to fall, and Richardson was stunned to see the 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 did not have one.
“However, this doesn't happen that often because in our long-term study we have over 4,600 individual bears that we've known over the last 45 years, and literally hundreds and hundreds of litters. [of cubs]” he said about adoption.
Researchers estimate that the mother is about five years old and the cubs are about 10-11 months old.
Richardson doesn't know for sure why the mother adopted the lonely stray cub, but he has a hypothesis.
“We really think it's just because [polar bears are] so maternally charged and such good mothers that they simply cannot leave a crying cub in the tundra. So they pick them up and take them with them,” he said.
Polar bear cubs typically stay with their mothers for two to two and a half years.
“It doesn't take that long to learn how to be a polar bear, but during that time they learn a lot of lessons. The cubs have about a 50 percent chance of surviving to adulthood… but if we find out the cub doesn't have a mom, it has almost no chance,” McCall said.
She said the adopted cub now has a good chance of reaching adulthood.
It is unknown what happened to the foster cub's biological mother, but Richardson hopes the genetic data sample his team was able to obtain from the cub could provide some information.
The National Weather Agency is working with Polar Bears International and the University of Alberta's polar bear science program to collect data on bears using GPS collars. The movements of tagged bears may also be tracked online.
Female polar bears in western Hudson Bay have been collared for decades, although only about 10 of them are collared each year, McCall said.
It's rarer to get a polar bear cub adopted, and even rarer to see it in person.
“Bears need all the help they can get with climate change,” Richardson said. “The females have the opportunity to pick up another cub, care for it and successfully wean it. That's good for the bears in Churchill.”
