Researchers in northern Canada saw a rare event this fall: a mother polar bear adopted a cub that was not biologically hers. The five-year-old mother and her cubs were spotted near Churchill, Manitoba, known for its polar bear population. "It's unusual," said Alyssa McCall from Polar Bears International. "We don't really know why it happens...but we know it doesn't happen often at all." This is only the 13th known adoption among 4,600 bears studied over nearly 50 years. The mother was first tagged in spring with one cub. But in the fall, she was seen with two cubs—one tagged, the other not. Scientists are trying to find out what happened to the new cub's biological mother through genetic testing. Evan Richardson of Environment and Climate Change Canada said, "The bears need all the help they can get these days with climate change. If females have the opportunity to pick up another cub and care for it and successfully wean it, it's a good thing for bears in Churchill." Polar bear cubs have only a 50% chance to survive adulthood, but mother care improves their survival. The cubs look healthy and will likely stay with their mother until about two-and-a-half years old. Then they will learn hunting skills on the sea ice. "It's just nice to know that the bears are looking out for each other," Richardson added.