Echolocation is the biological equivalent of sonar, and science has long known that toothed whales and bats rely on the same range of ultrasonic frequencies to hunt. Using a new type of whale tag called the DTAG, researchers recently found that the acoustic behavior of whales while tracking prey also mimics that of bats.
“Animal echolocation works just like a fish finder: The whale makes a click and then listens for the echoes,” says Woods Hole Oceanographic Institution’s electrical engineer Mark Johnson, who developed the DTAG. Bats increase the number of calls per second (called a “buzz rate”) while hunting, while whales were thought to maintain a steady click rate. But new research shows that wild whales also increase their rate of clicks during a kill — and that whales’ buzz rates are nearly identical to that of bats, at about 500 clicks per second.
The new tags might help assess environmental impacts on whales’ behavior by explaining how they cope with louder seas. “The oceans have become much noisier places, which has a major impact on echolocating animals,” says Johnson. “These animals rely on being able to hear faint echoes from distant prey. Background noise acts like an ‘acoustic fog,’ drastically reducing the distance over which they can find prey.”