Scientists Record Penguins Making Sounds Underwater for the First Time

Researchers have recorded penguins making sounds underwater for the first time—the first time such behavior has been identified in seabirds.

These animals, like other seabirds, are highly vocal on land and they are known to communicate when their heads are above the water in the ocean, possibly for the purposes of group formation.

However, until the latest study—published in the journal Zoological Science—it was not known whether penguins made sounds underwater, like some other air-breathing marine predators, such as whales and dolphins.

For their research, a team of scientists led by Andréa Thiebault from Nelson Mandela University in South Africa, wanted to investigate this issue. To do so, they fitted adult penguins from three species—king, gentoo and macaroni—with video cameras featuring built-in microphones.

To the surprise of Thiebault and colleagues, the team recorded a total of 203 underwater vocalizations from the penguins in underwater footage captured over a month-long period in 2019. These are the first recordings of seabirds producing vocalizations underwater.

"I couldn't believe it. I had to replay it many times," Thiebault told Hakai Magazine.

The vocalizations that the team recorded—which sound like rapid whoops—were very short in duration, lasting about 0.06 seconds on average. And all of them were emitted during dives in which the animals were searching for food.

Currently, it is not clear why the penguins are making these sounds; however, they only produced them while hunting. in fact, more than 50 percent of the vocalizations were immediately preceded by an acceleration movement and/or followed by an attempt to capture prey.

According to the researchers, this suggests that the sounds are related to hunting behavior—especially because the penguins tended to be alone when they made them, indicating that communication was not the purpose.

The researchers speculate that the penguins may be using the vocalizations to stun their prey. However, much more research is required to determine why the penguins make these sounds, the scientists note.

For now, "just the fact that we discovered this behavior is intriguing," Thiebault said.

Hannah Kriesell, a biologist from the Norwegian University of Science and Technology, who was not involved in the research, told Hakai that the latest findings "open the door for a lot more research."

gentoo penguin
A gentoo penguin stands on an ice stone in front of the Brazilian Comandante Ferraz Station, on December 20, 2019 in King George Island, Antarctica. Alessandro Dahan/Getty Images

She suggests that scientists could shed light on the purpose of the vocalizations by conducting experiments where the sounds are played underwater in a controlled setting to determine their effects on prey animals.

Scientists know that vocal communication among seabirds plays a crucial role when it comes to breeding and reproduction.

"While breeding, adults regularly commute between their foraging grounds at sea and their breeding colonies on land where they engage in nest care and chick provisioning," the authors wrote in the study. "Every time they return to the colony, they must find and identify their partner and/or their offspring. In this context, acoustic signals are necessary for individual recognition."

However, their use of vocal sounds at sea—where they spend most of their time—is poorly understood.