Dolphins Hook Up With Individual Whistles

W A S H I N G T O N, Aug. 24 -- Dolphins greet one anotherby “name,” using signature whistles to keep track of oneanother in murky waters and across distances, a researcher saidtoday.

While he hesitates to say the dolphins are actually usinglanguage, the researcher said the study shows dolphins have aclear and consistent vocabulary and are able to identify oneanother as individuals.

“Each dolphin develops a very specific signature signal,”biologist Vincent Janik of the University of St. Andrews inScotland, who conducted the study, said in a telephoneinterview. “They always use the same call. Some people call ita name.”

Like a Screen Name

But because the dolphins seem to develop their ownsignature whistles, Janik said the calls are more like Internetscreen names or handles.

Janik studied wild bottlenose dolphins off the Moray Firth, onScotland’s coast. He recorded 1,719 whistles using sixhydrophones and a computer-based method for finding individualdolphins as they made the calls.

The dolphins were coming into the bay to catch salmon.

“You have lots of dolphins all over the place,” Janik said.“Obviously at some point they want to get together again.”

Each dolphin makes its own, distinctive whistle, Janikfound. Other dolphins will imitate that whistle, presumably tocontact and keep in touch with that particular dolphin.

“It’s like keeping in acoustic contact,” Janik said.

“It’s something that we know from birds and humans, too.”

Human Judges

To check his work, Janik used five human “judges” toconfirm the calls were identical. People are very good athearing differences in tone, he said.

“I used human judges because a computer is not up to thejob yet,” he said.

“I can say the same word in a high-pitched voice or alow-pitched voice and it’s still the same word but the computercould confuse it.”