Bottlenose Dolphins Answer When You Whistle Their Name

Picture a calm summer morning in a bay on the east coast of Scotland. A small boat drifts on flat water, a few grey fins rise and roll nearby, and the researchers on board lower an underwater loudspeaker over the side. They are about to say hello to a dolphin, in the only way the dolphin is likely to understand: by whistling its own name.

A whistle that works like a name

Each bottlenose dolphin develops its own signature whistle early in life, a pattern of rising and falling pitch that belongs to that animal alone. The Sarasota Dolphin Research Program in Florida, which runs the longest study of any wild dolphin population in the world and began in 1970, describes these whistles as identifiers, used much as people use names. Signature whistles also make up a large share of what dolphins say. In a paper published in 2013, Stephanie King and Vincent Janik of the University of St Andrews reported that a dolphin kept on its own produces almost nothing else, while in wild groups they make up about 38 to 70 per cent of all whistles. The university's own summary of the work rounds this to about half.

How the experiment worked

King and Janik recorded wild dolphins in the Moray Firth and St Andrews Bay, then made computer versions of their signature whistles and played them back into the water. Some dolphins heard their own whistle, some heard the whistle of a dolphin they had never met, and some heard a familiar whistle from their own neighbourhood. They responded only to their own. In 8 of the 12 playbacks of a dolphin's own whistle, the group called back, as if answering to its name.

• 38–70% of whistles in wild groups are signature whistles
• 8 of 12 playbacks of a dolphin's own whistle got a reply
• 20+ years a former companion's whistle can be remembered
• 43 years the longest time one Sarasota dolphin has been recorded

What people often get wrong

It is tempting to imagine dolphins chatting away and dropping each other's names into every sentence. The evidence is more modest. Copying another dolphin's signature whistle is relatively rare, the authors write, and they could not tell which animal in the group was the one that replied. The name is not a word in a spoken language either. What carries it is the shape of the whistle, not the sound of a particular voice: the computer copies had no voice features at all, and the dolphins still recognised them.

How long a name is remembered

A name is only useful if it is remembered, and dolphins seem very good at that. The Royal Society reported a 2013 study by Jason Bruck, who played signature whistles to 53 bottlenose dolphins at six facilities that had kept careful records of which dolphins had lived together. The dolphins recognised the whistles of old companions after being apart for more than 20 years, the longest social memory recorded for any animal other than humans.

So a dolphin carries its name through life, answers to it, and keeps the names of old friends for decades. Next time you hear a friend call your name across a busy beach, you are doing something a dolphin out in the bay would recognise at once.