Dolphins communicate by mimicking those closest to them, according to the latest research by a Scottish university.
The new study, by marine biologists at the St Andrews University, showed that dolphins only copy those that they share strong social bonds with.
The team of Scottish and American scientists studied dolphin ‘signature’ whistles to find out why they appear to copy one another.
In fact, they only found copying present in mothers and their offspring and adult males, who copied those they had long-term associations with.
The research was carried out by Drs Stephanie King and Vincent Janik from St Andrews alongside Dr Laela Sayigh from the Woods Hole Oceanographic Institution, Dr Randall Wells from the Chicago Zoological Society and Dr Fellner from the Walt Disney World Resort.
Dr King said: "Interestingly, signature whistle copying was only found in pairs of animals composed of mothers and their calves or adult males who form long-term alliances with one another.
"The fact that animals are producing whistle copies when they are separated from a close associate supports the idea that dolphins copy another animal’s signature whistle when they want to reunite with that specific individual.
"Our next step is to use sound playbacks to see how dolphins respond to being matched with a copy of their own signature whistle. If they react we would know that copying of signature whistles can be used to address dolphins."
The scientists analysed acoustic recordings from wild and captive dolphins to identify which animals copy one another's individually distinctive signature whistle. The team also found that dolphins introduce slight changes into copies to avoid confusing listeners.