Killer whales shocked scientists by mimicking the sounds of dolphins and using the new sounds and calls in social situations.
A research team found cross-species vocal learning tends to occur in killer whales if they socialize with bottlenose dolphins, Acoustical Society of America (ASA).
Killer whales communicate through clicks, whistles, and pulsed calls; these patterns have developed into "dialects" among different groups of whales.
"There's been an idea for a long time that killer whales learn their dialect, but it isn't enough to say they all have different dialects so therefore they learn. There needs to be some experimental proof so you can say how well they learn and what context promotes learning," said Hubbs-SeaWorld Research Institute senior research scientist Ann Bowles.
Dolphins rely more on clicks and whistles to communicate than killer whales. The research team compared the calls of whales kept exclusively with others of the same species with those of animals that lived in the same tanks as bottlenose dolphins. All three observed killer whales that had lived with dolphins for several years shifted the proportion of calls in their repertoire to produce more clicks and whistles. The team also found the whales learned to make entirely new sounds, such as a chirp sequence that had ben taught to the dolphins by human handlers.
The findings suggest whales have a high level of neural plasticity, which is the ability to change circuits in the brain and apply new information.
The whales' ability to pick up new vocal patterns has implications on their ability to adapt to shifting territories and social groups. Killer whales are threatened by human activity, and these findings could help minimize the impacts.
"It's important to understand how they acquire [their vocalization patterns], and lifelong, to what degree they can change it, because there are a number of different [cetacean] populations on the decline right now," Bowles said. "And where killer whales go, we can expect other small whale species to go -- it's a broader question."
The findings were published in a recent edition of The Journal of the Acoustical Society of America.
