A study by Scotland's Univerisity of St Andrews discovered that the dolphins mimic the distinct individual signatures of those that they are close to - either offspring or those they have strong social bonds with - when they want to be reunited with them.

The St Andrews researchers, working with scientists at the Walt Disney World Resort in Florida, found the mimicking  by mothers and their offspring and among adult males.  

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 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.'