“The use of acoustic signals at sea could potentially enhance seabirds’ foraging success, but this remains largely unexplored,” says AndrĂ©a Thiebault at Nelson Mandela University in South Africa.
Thiebault and her colleagues taped cameras with audio recorders to the backs of six King, 10 Gentoo and two Macaroni penguins at Marion Island, South Africa. The recording equipment was housed in aluminium tubes to withstand the pressures at depths of up to 300m, where these animals hunt.
The team recorded 203 vocalisations from all three species during four hours and 43 minutes of underwater footage.
The sounds were very short chirps – 0.06 seconds on average – and very different from the penguins’ intensively studied land vocalisations, which are around three seconds long, much louder, and include a variety of different sounds.
“It is challenging and so exciting to study such little-known behaviour,” says team member Thierry Aubin at the National Centre for Scientific Research in France.
Prior to the study, the team had been studying how Cape gannets and African penguins interact with their own species on the surface of the sea during foraging trips.
“With African penguins, we found their calling increased in frequency when they went out feeding on their own. This told us that they call to aggregate or attract other penguins…as their foraging success is greater when they forage in groups,” says Pierre Pistorius at Nelson Mandela University.
While they’re still figuring out what the penguins are saying under water, most of the vocalisations took place just before capturing prey. So, they could mean anything from “Hooray, food!” to “Help me catch it”, says Pistorius. They might even be used to disorientate prey.
This article was written by Nicky Wilemse and was featured in:
The New Scientist: https://www.newscientist.com/article/2238025-penguins-call-out-as-they-hunt-under-water-but-were-not-sure-why/
The Weekend Argus: https://www.pressreader.com/south-africa/weekend-argus-sunday-edition/20200329/281895890340184
A study of king penguins at Marion Island (pictured here) – along with two other species – revealed that they chirp under water. Photo by: Florian Orgeret