Research shows Caribbean sperm whales share a unique regional call.
If you want to know where someone comes from, you might listen to how they speak. Their accent or use of particular words may give you clues to their provenance. As it turns out, the same is true for whales. In a new study, scientists show how sperm whales from the Caribbean share a distinct call that whales from elsewhere in the world don’t make. And that’s not all: besides saying where they’re from, these whales also have specific calls for their family units, and even unique calls for themselves—names, of a sort.
Shane Gero, the lead author of the study and a research fellow at Aarhus University in Denmark, has been recording sperm whale calls in the Caribbean for more than a decade. Gero and his colleagues had previously suggested that whales may have individual calls, but that earlier work only involved a few whales. They also knew that whales in the Caribbean sounded different from Pacific sperm whales. Now, Gero is back with nearly 4,000 sperm whale calls recorded between 2005 and 2010. The large number of recordings in this study confirmed the existence of individual calls and showed that the Caribbean whales all share a call.
Using the huge number of calls—which sound like a series of clicks, and are also called codas—the scientists show how whales from across the Caribbean use a particular coda that doesn’t vary from whale to whale. When they make that call, “even using computers, we can’t tell individuals or [family] units apart,” says Gero. This uniformity, even among animals that don’t ever interact, indicates that this is a socially learned call across a shared culture, he says.
Gero contrasts the whales’ unwavering Caribbean coda with the calls that are distinct to each individual or family group. These three levels of codas—highly variable individual calls, shared family calls, and uniform regional calls—match the complex hierarchy of sperm whale communities in that they support the “social complexity hypothesis,” which says that species with more complex social structures should also have more complex communication.
“It’s an amazing data set,” says Stephanie King, a behavioral biologist at the University of Western Australia who discovered that bottlenose dolphins can learn each other’s “names” and was not involved in this research. Now that they have identified these codas, King thinks the next step should be playback experiments to see how whales respond to the various calls, something she’s done in her research on dolphins.
Besides the codas identified in this study, Gero says that there are about 20 other types of codas with roles they haven’t yet deduced. Figuring it out is no easy task: Gero compares it to suddenly being dropped in a foreign land and trying to understand the local language with just a microphone. But Gero hopes to figure it out before it’s too late: the Caribbean population of sperm whales is declining by about three to five percent every year.