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Groups of pilot whales have different dialects

New research has revealed how pilot whales have their own accents depending on which social group they belong to.

Similar to the regional dialects you find in the United States and across the globe, researchers from the Woods Hole Oceanographic Institution (WHOI) discovered that short-finned pilot whales found off the coast of Hawaii have distinct dialects unique to their pod and families in a new study.

“These groups of pilot whales all use the same habitat. The fact that they have different vocal repertoires means that they’re purposely not associating with each other,” said Amy Van Cise,  the lead author of the study. “It’s sort of like if you’ve got hipsters and prep kids in the same high school–each group has different slang. They identify themselves with certain speech to maintain that separation.”

The study, published in the journal Behavioral Ecology and Sociobiology, expands on previous pilot whale research undertaken by both Robin Baird from the Cascadia Research Consortium and Van Cise.

Baird, a co-author on the new study, worked to create a database of pilot whale associations off the coast of Hawaii by photographing and categorizing groups of whales in a previous 15-year study.

Van Cise reviewed this database and noticed a pattern in how the pilot whales in Baird’s study were grouped. A unit was made up of intermediate family, clusters were made up of extended family, and clusters of whales came together to form a community.

Van Cise along with Baird then went out to record the pilot whales using underwater microphones over the course of several years. The two also collected genetic samples of the whales they did find.

Next, a team of researchers led by Van Cise listened to the recordings and organized the types of calls. The researchers were able to categorize the calls by group.

“That let us effectively make a map of vocal repertoire that we could superimpose onto a map of the whales’ social structure,” said Van Cise. “If two social groups sound similar to each other acoustically, that likely means that they’re communicating with each other regularly, using similar habitats or hunting grounds and foraging habits. This gives us a better sense of the social ties between whale groups. In the long term, that could help us understand both their genetic diversity and their evolution.”

Pilot whales are an understudied species of whale, and little is understood about their social behavior.

“On a broad-scale they are understudied, mainly because of where they spend their time,” said Baird. “Hawai’i is one of the only locations in the U.S. where you can fairly quickly and easily get to areas where you can find pilot whales, while staying in good working conditions.”

These types of studies are important because they can provide future research with a better understanding of how pilot whales communicate and function within their complex social groupings.

“Although pilot whales are not currently endangered, they still face a number of threats. They’re hunted in many countries around the world, and we think they may be sensitive to navy sonar or other human-made noise in the ocean,” said Van Cise. “When you hear of mass whale stranding incidents on a beach, it’s often pilot whales, because the entire social group strands. That’s the strength of the social tie–if the leader of a group beaches itself, all the animals in the group will beach themselves.”

By Kay Vandette, Staff Writer

Image Credit: Amy Van Cise, Woods Hole Oceanographic Institution

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