While using DNA collected with a crossbow and modified arrows to create a family tree of the North Atlantic right whale, biologist Timothy Frasier discovered that two mothers had switched and raised each other’s calves, the first confirmed case of double adoption in the critically endangered species.
Frasier, a professor at Saint Mary’s University in Halifax, made the discovery while trying to match the genetic profiles of whales whose tissue samples are stored in a DNA bank at Trent University in Peterborough, Ont., with photo-identification data from Boston’s New England Aquarium. There are only about 450 North Atlantic right whales left in the world, and scientists have been studying the animals for 30 years in an effort to determine why the population — threatened by ship collisions and low birth rates — has not recovered from whaling as other species have.
Little is known about the reproductive habits of right whales, but Frasier speculates that the calves were born during a terrible storm off the coast of Georgia or Florida more than two decades ago. The calves were likely unable to stay in close contact with their mothers and ended up bonding with the wrong female.
“You don’t expect that in nature,” says Frasier. “Whales have pretty low reproductive rates, so each offspring means a lot. There’s no real reason to raise an offspring that’s not yours.
”Like many species, a right whale typically ignores any young that is not its own, and a nursing calf will die if it is separated from its mother. There have been cases of bottlenose dolphin and polar bear adoption, but Frasier doesn’t know of any other instance in which two newborns were accidentally switched at birth.
The switch doesn’t appear to have affected these lucky whale calves: they are now 23 years old and producing their own offspring. Which raises a lot of questions about their reproductive habits and how quickly a mother and her young bond.
“People get lulled into this idea that we really understand what’s going on with North Atlantic right whales,” says Frasier, “but every once in a while, we find these little quirks. It’s an important reminder that we have a long way to go and of just how valuable these long-term studies are.”