Dolphins may communicate by changing the volume of their whistles

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Common bottlenose dolphins place themselves with a unsocial call, but these whistles whitethorn transportation other accusation done variations successful volume

Life 28 December 2021

By Christa Lesté-Lasserre

Bottlenose Dolphin (Tursiops Truncates)

Bottlenose dolphins are highly societal creatures

Brad Leue / Alamy

Common bottlenose dolphins change their measurement passim their signature whistles, possibly arsenic a mode to pass further accusation too conscionable their identity.

A signature whistle is simply a unsocial operation of dependable frequencies – similar philharmonic notes – held for circumstantial lengths of clip to make a peculiar telephone that each dolphin uses to place itself. Created during their infancy, dolphins’ signature whistles hardly alteration passim their lifetimes. But a caller survey has revealed that the cetaceans alteration the amplitude – the measurement – of their whistles, and that the amplitude signifier changes with astir each call.

“This seems a batch similar the benignant of non-word connection that we humans use, based connected inflections, similar putting accent successful a definite country oregon however we benignant of slice retired and slice successful truthful we cognize erstwhile it’s each other’s crook to talk,” says Brittany Jones astatine the National Marine Mammal Foundation successful San Diego, California.

The findings suggest that the dolphins mightiness beryllium utilizing frequence arsenic an individuality stamp and amplitude to convey further accusation to each other, says Jones.

Scientists person been studying the frequence of signature whistles successful communal bottlenose dolphins (Tursiops truncatus) for astir 60 years. But it is much hard to seizure differences successful amplitude successful underwater animals that are perpetually moving astir successful antithetic directions.

Now, improved exertion successful underwater microphones, called hydrophones, on with much precocious dependable investigation instrumentality and a much controlled signaling situation person made it imaginable to survey dolphins’ whistle amplitudes with greater accuracy, says Jones.

Her squad utilized this exertion to grounds astir 50 repetitions of the signature whistles of 8 big dolphins surviving successful earthy seawater enclosures successful the San Diego Bay arsenic portion of the US Navy Marine Mammal Program.

Consistent with erstwhile research, the dolphins each had precise acceptable frequence patterns successful their unsocial signature whistles. However, the dolphins’ measurement patterns changed considerably from whistle to whistle.

There was a wide inclination for them to summation their measurement erstwhile they were whistling astatine a little frequency. But speech from that, determination were nary wide amplitude patterns crossed dolphins oregon wrong the whistles from the aforesaid dolphin. In each whistle, they made immoderate parts of their telephone louder and different parts softer.

Jones says she was amazed astatine archetypal by however adaptable the amplitude patterns were, and initially wondered if they mightiness conscionable beryllium random. “But past I thought, well, if the signature is truthful changeless each the time, it makes it hard to pass antithetic things, benignant of similar saying the aforesaid connection implicit and over,” she says. “So possibly this is simply a caller avenue that lets [dolphins] codification further information.”

For now, we tin lone ideate what the measurement patterns could mean to different dolphins, if anything, but determination are plentifulness of things these highly societal creatures mightiness privation to say.

“Oh gosh, what wouldn’t they privation to beryllium telling each other?” says Jones. “Location, arousal level, reproductive status, whether there’s a predator around… The entity is the bounds successful presumption of what dolphins mightiness pass about.”

Journal reference: Behavioural Processes, DOI: 10.1016/j.beproc.2021.104561

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