It might be tough for dolphins to remember faces, considering they always look like they're smiling. But new research indicates they apparently never forget a voice.
That's one finding from a research project by University of Chicago doctoral student Jason Bruck that represents, he says, "a decoding of their whole communication system - at least the start of that."
Bruck, who is working with dolphins at Brookfield Zoo and five other facilities, plays recorded whistles of dolphins that had been in the same tank 20 years earlier but hadn't seen their tank mates in that time. When that happens, the dolphins swim toward the signal. When he plays the whistles of unfamiliar dolphins, the signal is ignored or, in some cases, imitated.
Based on detailed observations of dolphins and multiple underwater microphones, Bruck's research also suggests that dolphins are able to determine family relationships of other dolphins through whistles, and that mother dolphins "cluck like chickens" to call their calves.
One dolphin even adopted the local dialect of whistling when he resided in Brookfield for a year, said Bruck, who started the project in 2007.
Maybe it's no surprise, but females appear better at whistle interpretation than males, he said.
"The ladies are keeping track of who's who," Bruck said, "and the boys are like, 'whatever.'"
Explore further: Sharks found to exhibit altered swimming behavior when exposed to more acidic water