SAN JUAN, Puerto Rico, Sept. 30 (UPI) -- Two distinct species of dolphins with separate calls and sounds seem to attempt to find a common language when they come together, a U.S. researcher says.
Bottlenose and Guyana dolphins, two distantly related species, often come together to socialize in waters off the coast of Costa Rica, and although each species normally makes distinct, different sounds, they change the way they communicate when together and begin using an intermediate language, the BBC reported Thursday.
Biologist Laura May-Collado of the University of Puerto Rico in San Juan made the discovery while studying dolphins swimming in Costa Rica's Gandoca-Manzanillo Wildlife Refuge off the country's southern Caribbean coast. When bottlenose dolphins swim together, they emit longer, lower frequency calls that are modulated, she said. In contrast, Guyana dolphins usually communicate using higher frequency whistles that have their own particular structure.
But the two species often swim together in one group and when they do they produce quite different calls, May-Collado has discovered. Calls emitted during these multi-species encounters are of an intermediate frequency and duration, a style that is somewhere between those of the two separate species.
"I was surprised by these findings, as I was expecting both species to emphasize, perhaps exaggerate, their species-specific signals," May-Collado told the BBC. "Instead the signals recorded during these encounters became more homogenous."
May-Collado said she could not be sure whether both species are changing the way they communicate, or if it is one species attempting to call more like the other.