Researchers tracking wild polar bears in northern Canada witnessed something exceedingly rare this fall: a mother bear adopting a cub that was not biologically her own.
The five-year-old mother bear and her 10- to 11-month-old cubs were observed and captured on camera during the annual polar bear migration along the Western Hudson Bay near Churchill, Manitoba, a town known for its polar bear population.
"It's unusual," Alyssa McCall, a scientist at Polar Bears International, said in a video. "We don't really know why it happens...but we know it doesn't happen often at all."
It's only the 13th known case of adoption out of the 4,600 bears studied for nearly five decades in the area.
The mother bear was first captured as she emerged from her maternity den this spring. At the time, she had one cub, which scientists tagged for study.
