It has long been suspected that penguins make noises underwater, but it has never actually been proved. Now an accidental discovery has shown that it does in fact happen across multiple species.
Penguins are known amongst researchers as one of the noisiest seabirds on the planet. On land they are constantly calling to one another to locate their mates and offspring amongst colonies of thousands. They also make calls to each other at the surface when in the water. However until recently the question as to whether or not they make noises underwater has been completely theoretical, with no evidence to back it up. That is until a surprised researcher discovered their vocalisations for the first time, whilst reviewing underwater footage of their diving behaviour. Not only was this the first sound recording of penguins underwater, but it was also the first audio captured of any seabird below the surface. It is just the latest in a long line of discoveries to highlight the importance of sound to marine animals and why noise pollution is such a big problem.
A happy accident
The discovery was made by Andréa Thiebault, a researcher at Nelson Mandela University in South Africa, whilst she was reviewing video footage captured on special penguin-borne cameras. She and her team attached lightweight cameras, designed to withstand increased pressure, to the backs of eight king, three macaroni and 14 gentoo penguins, to try and learn more about their diving behaviour. What they found was something even more interesting and valuable. “I couldn’t believe it” says Thiebault talking to Hakai magazine, “I had to replay it many times”. What she had heard, only very briefly, was the sound of a penguin calling underwater. However it wasn’t just a one-off behaviour, in total vocalisations were made 203 times in the ten hours of footage recorded and across all three species. Their results were published in a recent study in the journal PeerJ.
What are they calling for?
Of course capturing this new behaviour meant next trying to explain why the penguins were doing it at all. The calls were very short and high pitched, on average around 0.06 seconds in length, and varied amongst the different species. The research described them as ‘whoops’, which is about as accurate a word there is to describe them. When matched up with the video it was obvious that it had something to do with feeding, as the noises were made shortly before the birds would lunge towards their prey. It could be to do with echolocation like that used by dolphins and killer whales, although penguins have excellent vision and were only doing it at very close range, so it seems unlikely. The best guess right now is that it is to stun their prey to make it easier to catch, an idea which would support the fact the calls have never been heard in captivity where they are fed dead fish. Either way it is obvious that this newly discovered behaviour is likely very important to their survival.
You can check out these brand new noises for yourself below (apologies for the super annoying background music).
It is unsurprising that sound is as important to penguins under the surface, as it is above it. All air-breathing marine predators have been shown to rely heavily on sound to hunt, navigate and communicate. Large baleen whales have been recorded singing to one another across entire ocean basins. Dolphins use rapid fire clicks to echolocate their prey and communicate among complex social groups. Even clapping underwater has been observed in grey seals, to ward off rival males. Unfortunately the ocean is becoming an increasingly noisy place as anthropogenic sources of noise pollution including shipping, mining, fishing, sonar and even renewable energy, which is making it much harder for marine creatures to hear one another. So it is more important than ever that we start to consider these auditory animals as we continue to share their environment with them.