A couple of years ago, researchers from the University of St. Andrews discovered that sperm whales added identifying sounds to the beginnings of their songs. In essence, the whales were stating their names before each recital. Now Stephanie King and Vincent Janik from the same university have shown that wild bottlenose dolphins may be doing the same thing.
The scientists found that each dolphin has a unique signature whistle. When the researchers played those signature whistles to a group of wild dolphins, the whistles were repeated back. In contrast, when an unfamiliar whistle was played to the dolphins, they did not respond to it. This suggests that the dolphins recognized their signature whistles.
To be clear, the authors could not determine whether each dolphin was responding only to its own ‘name’ or whether another group member was repeating back a familiar whistle. In other words, we can’t infer the animals motivation in copying back whistles. Were they saying, ‘Yup, that’s me’, or ‘Hey, someone's talking about Bob’? By the same token, we don’t know whether dolphins can only state their own names or if they can address each other by issuing specific whistles. Based on experiments with captive dolphins, the animals certainly seem capable of that cognitive feat. Who knows, perhaps in the future we'll be able to translate dolphin conversations.