Scientists Capture Penguins Making Sounds Underwater in a Way We've Never Seen Before

Penguins are adorable creatures, but they also get a lot of attention for their peculiar social behavior, which includes courtship rituals and communication. In 2019, Andréa Thiebault and her team members quietly slipped into Marion Island, a sub-Antarctic island off South Africa, and crawled close to penguin nests, waiting for them to step out. As penguins started to leave their breeding colonies to hunt at the sea, the researchers captured some of them. They strapped the backs of these seabirds with tiny waterproof cameras and attached microphones.

In early 2020, they published their findings in the journal Zoological Science, titling it “First evidence of underwater vocalisations in hunting penguins.” To their surprise, these penguins had been “talking” underwater.

While it was previously known that many marine animals like whales and dolphins and many air-breathing marine predators like seals, cetaceans, pinnipeds, and turtles are quite likely to produce sounds while eating or mating underwater, penguins doing so was unexpected. Penguins have always been known for their exceptional diving abilities, but they were never considered capable of underwater communication. The study provided “the first evidence that penguins emit sounds under water when they hunt,” Theibault wrote in The Conversation. Thiebault, who is from Nelson Mandela University in South Africa, led the team while monitoring the penguins. They chose three penguin species to log their data, namely, king, gentoo, and macaroni.

“These species were chosen because they reflect the diversity of feeding strategies in penguins. The King penguin is specialised to feed on fish at a substantial depth (3.2 feet), whereas the Macaroni penguin feeds mostly on schooling krill within the first 32 feet of the water column. In contrast, the Gentoo penguin displays a very diverse foraging strategy, feeding on all sorts of prey at all depths,” the team wrote.

Overall, the team collected “203 underwater vocalizations from the penguins” in the underwater footage captured over a month-long period. These became the first-ever recordings of seabirds chatting with each other. "I couldn't believe it. I had to replay it many times," Thiebault told Hakai Magazine. The vocalizations sounded like rapid whoops and were very short in duration, lasting about 0.06 seconds on average. All of them were emitted during dives in which the animals were foraging for food.

The purpose of these sounds, however, is not clear to scientists. But immediately after these sounds were produced, there was an accelerated movement, followed by an attempt to capture prey, which indicated that the penguins could be producing these sounds to bamboozle a meaty fat prey. For now, Thiebault said, "just the fact that we discovered this behavior is intriguing.”

This research also opens up possibilities for delving into the understanding of how penguins reproduce and breed. "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 noted 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."