At a young age, all dolphins learn to make their own unique whistling calls. These signature whistles, as they are called, were first noted some 30 years ago. Then in 1986 biologists observed that captive dolphins housed in separate tanks kept making their own distinct whistles and then began repeating the whistles of companions held in other tanks. Was this just some quirk of captive dolphins? Or could it be that the dolphins address each other, in essence asking another dolphin where it is? To find out, Vincent Janik, a biologist at the University of St. Andrews in Scotland traveled to Moray Firth, a channel near Inverness, where bottlenose dolphins come to feed on salmon and sea trout. He set up microphones on the shore to eavesdrop on the dolphins and found that mothers and infants seemed to copy each other’s whistles to keep in touch, while males may do the same in aggressive behavior to stake out territory. I think that once dolphins acquired the ability to learn vocally and to copy, they probably used it in a variety of different contexts, says Janik. It’s definitely an important factor in their communication system.