Short-snouted dolphins have the ability to 'talk' with harpoons of different species

Researchers discovered a wild short-snouted dolphin capable of conversing with harbor dolphins of different species, providing an example of interspecies communication.

The Firth of Clyde, a large saltwater bay on the west coast of Scotland, is home to thousands of harbor dolphins and a wild dolphin named Kylie. Researchers have never observed Kylie with other short-snouted dolphins (Delphinus delphis) for at least 14 years, but she is not alone. On clear Clyde days, visitors to the pier can sometimes see Kylie swimming with the harbor dolphin (Phocoena phocoena), a relative two-thirds its size.

Harbor dolphins near Shetland, Scotland.

New research published in the journal Bioacoustics shows that Kylie is much more attached to harbor dolphins than scientists imagined. While the sound of short-snouted dolphins includes a wide variety of calls such as clicks, whistles, and vibratos, Kylie does not whistle. Instead, it "talks" more like a harbor porpoise, which communicates through bursts of high-pitched clicks. Research indicates Kylie may be attempting to communicate with harbor dolphins, an example of the rich interactions between marine mammals, according to behaviorist Denise Herzing.

Years ago, the only short-snouted dolphin in the Clyde appeared at the mouth of Kyles of Bute, so locals called it Kylie. No one knows where the dolphin came from or why it was alone, said David Nairn, founder and director of Clyde Porpoise, an organization dedicated to the study and protection of marine mammals.

Some dolphins live alone after being separated from the herd due to storms, human activity, or orphanage. To learn more about Kylie's relationship with harbor dolphins, Nairn borrowed an underwater tuner and towed the back of his sailboat Saorsa. Nairn recorded audio from several encounters between Kylie and the harbor dolphins between 2016 and 2018.

Mel Cosentino, then a PhD student at the University of Strathclyde in Glasgow, mulled over thousands of cephalopod clicks from audiotape. While short-snouted dolphins whistle almost regularly, harbor dolphins never do. Instead, they use only narrow band high frequency (NBHF) clicks, with 8 - 15 peak amplitudes at 130 kiloherts. To hear an NBHF click, the researchers had to play the tape 100 times slower.

From the tape, Cosentino identified the standard low-frequency click of the short-snouted dolphin. But even when Kylie was alone, Cosentino detected clicks with at least eight amplitude peaks at 130 kilohertz, the frequency that harbor dolphins typically use to converse with each other. In other words, Kylie talks like a harbor dolphin. The team also found that it never whistled like short-snouted dolphins usually do.

Cosentino observed that the exchange between Kylie and the harbor dolphin was as rhythmic as that between members of the same species. They take turns talking and rarely overlap. However, the research team is not clear how much meaningful information the sound created by Kylie contains.