Researchers tracking free-roaming polar bears in northern Canada observed something exceedingly rare this autumn: a female bear adopting a cub that was not genetically her own.
The half-decade-old mother and her 10- to 11-month-old cubs were spotted and captured on camera during the annual polar bear migration along the Western Hudson Bay near Churchill, Manitoba, an area renowned for its polar bear population.
"This is uncommon," remarked a scientist with an international bear organization. "We don't really know why it happens...but we know it is a rare event at all."
It's only the thirteenth documented instance of adoption out of 4,600 bears studied for nearly five decades in the area.
The female bear was initially tagged as she came out from her maternity den this springtime. Initially, she had a single offspring, which scientists marked for study.
In the fall, she was seen again, but this time with two cubs - the original cub and a second without a tag. Researchers aren't sure what happened to the new cub's biological mother, but they are trying to identify her using genetic samples.
"The bears need every advantage they can get these days with climate change," noted a polar bear scientist. "If females have the opportunity to take in another cub and raise it and see it to independence, it's a good thing for the population."
Polar bears in the natural world only have a 50% chance of living into adulthood, but having a mother caring for them improves their chances.
The young bears appear to be in good condition, according to experts, and they will probably remain with their mother until they are about 30 months of age.
Following this, the family is expected to head out to the frozen ocean, where the youngsters will learn from their mother bear how to catch prey and live on their own.
"It is heartening to know that the animals are looking out for each other," added the scientist.
