Each dolphin makes its own, distinctive whistle. Others imitate that whistle, presumably to contact and keep in touch with that particular dolphin. That is essentially what the dolphins are doing. And it indicates that dolphins have developed the kind of brain power that underlies speech. Studies of other dolphins living in captivity had already offered clues in that direction, Dr Tyack said.
Captive dolphins are fantastic imitators of human sounds.
Within seconds of hearing a tonal pattern for the first time a captive dolphin can reproduce it accurately. To check his work, Dr Janik used five people to confirm the calls were identical. People were very good at hearing differences in tone, he said. I used human judges because a computer is not up to the job yet. Dr Janik has also found that, like monkeys and other primates, the dolphins use distinctive calls when they have found food.