Fans called him Flipper, but friends and relatives of the world's most famous dolphin might know him by another "name." According to researchers at Scotland's University of St. Andrews, the high-pitched squeals of bottlenose dolphins are unique personal identifiers, similar to human names. Dolphins learn to mimic each others' whistles in order to "call out" to another dolphin. They also use whistles to identify objects.
The concept of dolphin using unique vocal cues has been around for at least a decade.
In a study published in the 2006 in the journal Proceedings of the National Academy of Science of the United States of America (PNAS), a team of Scottish researchers found that "bottlenose dolphins develop individually distinctive signature whistles that they use to maintain group cohesion." The study went on to show that dolphins are the only mammal other than humans known to recognize another's identity regardless of the caller's voice and location.
Team members Stephanie King and Vincent Janik released a subsequent study in February in the journal Proceedings of the Royal Society B, offering further evidence that bottlenose dolphins recognize and are drawn to their relative's distinct whistles than to random whistles. The 2013 study added that mother's mimic their offspring's' whistle when they are separated, as if calling out a child's name, reports Smithsonian Magazine.
This week, PNAS released Janik and King's latest study, in which they studied the utility of the whistle.
"This whistle encodes individual identity independently of voice features. The copying of signature whistles may therefore allow animals to label or address one another," the authors wrote.
In researching the vocal cues, Janik and King collected data by playing back whistles through underwater speakers. After blindly coding the groups responses, the results showed that dolphins frequently respond to the unique calls of dolphins within their usual group, while the rarely -- it happened just twice in 22 trials -- respond to the calls from distant or unfamiliar groups.
The researchers could not determine if the dolphins were responding to their personal call or to the call of a fellow group member, because they had no way of knowing exactly which dolphin had responded when they played the research recordings back.
More research is needed to determine exactly how distinct each "name" is, but this study points to truth behind the concept of bottlenose dolphins developing names for their family and friends.