Dolphins respond to recordings of their own whistles—suggesting they use names to communicate in the wild, a new study says.
We already knew that bottlenose dolphins can follow "recipes" in preparing mollusks, help other species in distress, and possibly do math. So it may come as no surprise that the marine mammals also call each other by whistles that act as names.
Past studies have shown that individual dolphins have a unique whistle, called a "signature whistle," that they often use in big group settings, like when several pods of dolphins meet at sea.
The idea that dolphins have a name in the form of a whistle has been around since the 1960s, and studies of captive dolphins have shown that the animals are responsive to the whistles of dolphins they know.
But a new study takes the theory a step further by asserting that a dolphin will respond when it hears the sound of its own signature whistle, repeating that whistle back in a way that seems to say, "Yup, I'm here—did you call my name?" explained Whitney Friedman, a dolphin-behavior expert at the University of California, San Diego.
It's "compelling evidence" that the dolphin indeed uses the sound as a name, according to the study, published July 22 in the Proceedings of the National Academy of Sciences.
The research was performed by a group of scientists on a boat off eastern Scotland who joined up with a group of wild dolphins. When one of the dolphins announced itself with its signature whistle—the equivalent of "Joey!" for instance—the researchers recorded that sound.
Later, the team played that same "Joey!" call back to the dolphins, and a significant portion of the time, the dolphin they called Joey responded with the same call—as if Joey was saying, "Yup, I'm here."
The dolphins responded a little when the scientists played recordings of whistles of familiar dolphins from the same population, but did not respond at all to unfamiliar dolphins from a different population. (Watch video: "Dolphin Talk Decoded.")