Whales, dolphins, seals and even sea turtles can vocalise under water 鈥� and scientists have discovered that penguins can, too. It is the first time seabirds have been found to produce sound under water.
鈥淭he use of acoustic signals at sea could potentially enhance seabirds鈥� foraging success, but this remains largely unexplored,鈥� says Andr茅a Thiebault at Nelson Mandela University in South Africa.
Thiebault and her colleagues taped cameras with audio recorders to the backs of six king penguins, 10 gentoo penguins and two macaroni penguins at Marion Island, South Africa. The recording equipment was housed in aluminium tubes to withstand pressures at depths of up to 300m, where these animals hunt.
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The team recorded 203 vocalisations from all three species during 4 hours and 43 minutes of underwater footage.
The sounds were very short chirps 鈥� 0.06 seconds on average 鈥� and very different from the penguins鈥� intensively studied land vocalisations, which are around 3 seconds long, much louder and include a variety of different sounds.
鈥淚t is challenging and so exciting to study such little-known behaviour,鈥� 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.
鈥淲ith 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鈥� as their foraging success is greater when they forage in groups,鈥� says Pierre Pistorius at Nelson Mandela University.
While they鈥檙e still figuring out what the penguins are saying under water, most of the vocalisations took place just before capturing prey. Pistorius says the calls could mean anything from 鈥淗ooray, food!鈥� to 鈥淗elp me catch it鈥�. They might even be used to disorientate prey.
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