19 February 2013 Last updated at 19:40 ET

Study finds dolphins mimic calls of social group

Dolphins mimic the unique calls of those they share a strong social bond with, such as offspring

Dolphins mimic the distinct whistles of their closest companions as a way of tracking them, according to researchers.

A team of marine biologists from the University of St Andrews studied the vocal signatures of the mammals.

Their findings suggested that dolphins mimic those they are close to and want to be reunited with.

It was already known that dolphins develop their own individual whistle which describes their identity.

The team of Scottish and American scientists analysed recordings from wild and captive dolphins to identify which animals copy one another's signature whistle.

Social bonds

The St Andrews researchers, working with scientists at the Walt Disney World Resort in Florida, found the mimicking was only present in mothers and their offspring, as well as in adult males who copied those they had long-term associations with.

The research involved a group of dolphins in Sarasota Bay, which has been studied since the 1970s. The animals are brought into captivity for medical tests once a year, which allowed the marine biologists to record and study their calls.

Dr Stephanie King, from St Andrews University, said: "Interestingly, this mimicking only occurs in animals who have strong social bonds.

"It also only occurs when they are separated from each other, and this supports the idea that they want to reunite with the other animals.

"The next step is to do some experiments to play back their own calls and whistles to see if they can identify them."

The study also found that dolphins introduce slight changes into copies, avoiding confusion for the listener.

While vocal mimicking is found in other animals like song birds, the team believes dolphin calls offer an insight into the way complex language structures evolve.

Dr King said: "It is something we see in ourselves, but not in other animals.

"This could give us a real insight into how certain traits in language and communication have evolved."