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In a First, Researchers Record Penguins Vocalizing Under Water

But the scientists still aren’t sure what the birds are saying

A gentoo penguin swimming underwater. This species, as well as others, vocalizes while hunting beneath the water's surface, research shows. (Bernard Spragg. NZ / flickr)
smithsonianmag.com

We humans aren’t very good at communicating underwater, but down in the deep blue sea, plenty of other animals are capable of quite the marine ruckus—including, it seems, penguins.

For the first time, researchers have recorded the waddly, flightless birds making sounds during their deep sea dives, reports Nicky Willemse for New Scientist. The findings, described in a recent study published in the journal PeerJ, could clue scientists in to the communicative cues penguins rely on to hunt.

Simply knowing that penguins engage in underwater banter “opens the door for a lot more research,” Hannah Kriesell, a biologist from the Norwegian University of Science and Technology who was not involved in the study, tells Alejandra Manjarrez for Hakai magazine.

Those who have heard a penguin squawk on land might not find these results very surprising. Ashore, these birds often congregate in colonies, making calls and chirps important tools for passing information back and forth to mates, chicks and competitors. Some species will also produce an array of noises when bobbing on the sea surface. So it makes good sense that they’d continue their chatter underwater as well; but a lack of luck with timing and the right equipment has long stymied scientists’ efforts to catalogue the birds’ conversations.

To fill this crucial gap, a team led by Andréa Thiebault, a biologist at Nelson Mandela University in South Africa, outfitted 20 penguins from three different species—king, macaroni and gentoo—with small cameras and sent them off to swim. After collecting hours of footage, the researchers mined the tapes for bird sounds, counting more than 200 distinct underwater vocalizations.

Many sounded like brief, simple chirps, lasting just 0.06 seconds on average—far shorter from the sounds penguins emit on land, which are louder, more complex and can run several seconds apiece.

The researchers don't know what the calls communicate, or how crucial they are to the penguins’ hunting success. When feeding on land, some species will squawk out rallying chirps, asking their comrades to help them forage for food, study author Pierre Pistorius, a biologist at Nelson Mandela University, tells New Scientist.

Something similar might be at play when the penguins search for food underwater. But the birds taped by the researchers were often hunting alone when making their calls, suggesting they might have been directed at their prey instead. Many of the sounds were emitted right before the penguins snagged a meal of fish, hinting that they might even serve to stun or disorient their prey, Thiebault tells Hakai.

Then again, maybe the vocalizations are entirely benign—or even a simple pre-dinner celebration. Perhaps, Pistorius tells New Scientist, they’re just penguins’ way of saying, “Hooray, food!”

About Katherine J. Wu
Katherine J. Wu

Katherine J. Wu is a Boston-based science journalist and Story Collider senior producer whose work has appeared in National Geographic, Undark magazine, Popular Science and more. She holds a Ph.D. in Microbiology and Immunobiology from Harvard University, and was Smithsonian magazine's 2018 AAAS Mass Media Fellow.

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