Southern right whale moms and calves may whisper to evade orcas
Whales are known for belting out sounds in the deep. But they may also whisper.
Southern right whale moms steer their calves to shallow waters, where newborns are less likely to be picked off by an orca.
While most whale calls are meant to be long-range, “this shows us that whales have a sort of intimate communication as well,” says Mia Nielsen, a behavioral biologist at Aarhus University in Denmark. “It’s only meant for the whale right next to you.”
Nielsen and colleagues tagged nine momma whales with audio recorders and sensors to measure motion and water pressure, and also recorded ambient noise in the nearshore environment.
An orca, or killer whale, “would have to get quite close in the big ocean to be able to detect them,” says biologist Peter Tyack at the University of St. Andrews in Scotland.
The whispers were associated with times when the whales were moving, rather than when mothers were stationary and possibly suckling their calves.
“There may be a repertoire among the calls of lots of animals that are specifically designed only to be audible to a partner who’s close by,” he says.