Dolphins Use Signature Whistles As Names, Researchers Discover

Wild dolphins in Africa identify and address each other with unique signature whistles, researchers have discovered, in a process similar to the way human beings use names.

The vast majority of research exploring how dolphins communicate has been conducted on animals in captivity, the Daily Mail reports. Those findings have revealed that each dolphin learns a unique signature whistle that it exchanges with other groups of dolphins when they meet, in a process akin to introducing oneself. It was unclear to researchers, however, whether dolphins use the whistles for communication outside of captivity.

A new study has discerned that both the Indo-Pacific bottlenose dolphin (Tursiops aduncus) and the common bottlenose dolphin (Tursiops truncatus) use the signature whistles. Both species of dolphin are found in South Africa and Namibia.

Dr Tess Gridley of the University of Pretoria and the Namibian Dolphin Project and Sea Search led the study, and explains that researchers observed an isolated population of bottlenose dolphins in Walvis Bay, Namibia.

“We found that the number of different signature whistles recorded increased when group sizes were larger and when calves were present – something you might expect if signature whistles are used to address each other and help maintain contact between animals, particularly between mothers and calves,” Gridley explained.

As Planet Earth Online notes, the research in an important stepping stone for further study into how dolphins use the sounds, and the ways in which human activity affects them. Gridley fears that noise from nearby construction may be interfering with the dolphins’ communication, potentially blocking their signals.

“In the same way that the desert elephants or desert lions are small, locally adapted populations in Namibia’s terrestrial environment, the common bottlenose dolphins found along Namibia’s coastline should be considered quite an important population and are locally threatened by coastal construction and marine tourism,” She said.

Recently, another team of researchers concluded that orca whales were able to mimic the sounds that dolphins use. When socialized with dolphins, the whales’ vocalizations changed, potentially facilitating social interactions between the species, as the Inquisitr previously noted.

Using a hydrophone, Gridley and her colleagues collected over 79 hours of vocalizations, in addition to photos of the dolphins that produced them. Though it is already established that bottlenose dolphins utilize sound in various ways, and are able to even mimic what they hear, Gridley is hoping to determine whether the signature whistles can be used to monitor how dolphins use their habitat.

[Image: Alamy via the Daily Mail]