"…Quick and Janik recorded the calls of swimming dolphin pods using underwater microphones. From 11 such recordings, they worked out that dolphin groups use their signature whistles in greeting rituals, when two groups meet and join. Only 10 per cent of such unions happen without any signature whistles. And the dolphins use their signatures nine times more often during these interactions than during normal social contact. The signature whistles clearly aren’t contact calls, because dolphins hardly ever use them within their own groups. Mothers and calves, for example, didn’t exchange signature whistles when travelling together. And they’re not confrontational claims over territory, because bottlenose dolphins don’t have territories.…"
Posted by Maggie Koerth-Baker at: http://boingboing.net/2012/03/02/individual-dolphins-identify-t.html