Dolphins Call Each Other By Name

From National Geographic:

Dolphins give themselves "names"—distinctive whistles that they use to identify each other, new research shows. Scientists say it's the first time wild animals have been shown to call out their own names. What's more, the marine mammals can recognize individual names even when the sound is produced by an unfamiliar voice.

Bottlenose dolphins appear to develop so-called signature whistles as infants.

The idea that they use these whistles to identify each other was first proposed in 1991 after individuals were heard to make their own unique sounds. "The challenge was to show experimentally that the animals can use these independent voice features as signature whistles," said Vincent Janik of the Sea Mammal Research Unit at the University of St. Andrews in Scotland. Janik is the lead author of a study on the dolphin whistles to be published [today] in the journal Proceedings of the National Academy of Sciences.

He says the idea that dolphins use names "was fairly hypothetical, and some researchers regarded it as not possible." The research focused on wild bottlenose dolphins living in Sarasota Bay, Florida. Acoustic recordings have been made of most of these dolphins, which have been studied for more than 30 years. For the new study each dolphin's signature whistle was isolated from the recordings and then played back to the animals through underwater loudspeakers.
Janik says the recordings were synthesized electronically to rule out the possibility that the dolphins recognized each other simply by the sound of their voices.

"Group changes are incredibly dynamic, and you need a way of knowing exactly who's around you," Janik said. "Dolphins often prefer to spend time with particular individuals." But living in the murky ocean makes it hard to hook up with your dolphin buddies. "Finding each other isn't so easy in marine environments, because visibility is very poor—maybe just a couple of meters," Janik said. "Instead of looking around, they really need some other obvious and reliable system to find another animal."

"You really have to have something more than a voice. You need something that's as different as a name," Janik said.

The ability to develop individually distinctive calls requires vocal learning, a relatively rare skill that's seen in humans, dolphins, elephants, and a few other animals including certain birds.

The BBC News quotes Janik: "I think it is a very exciting discovery because it means that these animals have evolved the same abilities as humans. "