Dolphins Whistle Their Names with Complex, Expressive Patterns

Dolphins Whistle Their Names with Complex, Expressive Patterns
calls out to its peers. The animals vary these whistles widely, repeating sections in loops, altering the pitch, and adding and deleting short segments. A new study, published in Frontiers in Marine Science, evaluates these changes through a database of nearly 1,srcsrcsrc recording sessions that collected whistles from around 3srcsrc individual dolphins over four decades.*

To calculate the signature whistles’ variability and allow comparison with sounds from other species (particularly birds), the authors used a statistical metric that evaluates 21 different facets of a sound—such as length, frequency, pitch and pattern. The more each individual varied the facets in each call, and the more the calls varied between different individuals, the higher the species scored. Bottlenose dolphins’ identification sounds had the largest audio palette in a recent comparison paper, followed by larks’; researchers do not yet have a consensus on how humans measure up.

This metric is good for comparing across species, says Woods Hole Oceanographic Institution marine biologist Laela Sayigh, the dolphin study’s lead author. But she notes that the 21 facets barely scratch the surface of dolphin whistles’ true complexity. “It’s actually kind of phenomenal,” Sayigh says, that even using this “coarse” metric, “dolphins are the most individually distinctive communicators.”

University of South Bohemia behavioral ecologist Pavel Linhart, who was not involved with the study but led the interspecies comparison, says he is glad the researchers tallied this variability. “I think because it was just so obvious that it’s so easy to identify [individuals], they didn’t quantify it before,” he adds.

Scientists are just beginning to explore dolphins’ reasons for varying their signature whistles—possibly to express emotional states, for one. Future work will help decipher shared, nonsignature whistles that dolphins also exchange, Sayigh says. “We’re really in the infancy of understanding those.”

*Editor’s Note (1src/2src/22): This sentence was edited after posting to correct the description of 1,srcsrcsrc whistle recording sessions. 

This article was originally published with the title “Name Check” in Scientific American 327, 5, 25 (November 2src22)



    Rebecca Dzombak is a freelance science writer who covers Earth sciences and the world in the Anthropocene.

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