Spouting water, hissing and blowing bubbles might not work for humans on the dating scene, but for saltwater crocodiles it’s a different story.
That’s according to researchers from the University of the Sunshine Coast (UniSC), who are recording and classifying sounds made by the animals — the world’s most vocal reptiles — in a bid to aid conservation efforts.
Video and acoustic recording equipment installed in Australia Zoo enclosures as part of a 12-month project has captured a unique love language that includes narial geysering (spouting water from the nose), narial hissing and bubble blowing.
The recordings are being used to create a “crocodile dictionary” to be released in stages, starting mid-next year.
Research supervisor and UniSC ecologist Ross Dwyer said very little was known about how saltwater crocodiles communicated — something he realised while visiting Cape York in Far North Queensland.
“While we were camping there, we could hear the crocodiles vocalising along the river,” Dr Dwyer said.
“We could hear their head slaps; we could hear their growls and whistles.
“And while we’re out there we’re thinking, we should really be working harder to be able to classify these calls and see what extent these crocodiles are communicating to one another and under what context.”
The project is being led by honours student Sonnie Flores, focusing on the courtship noises of the zoo’s mature male/female breeding pairs.
It’s found the females are more likely to growl — especially when guarding a nest — while males are more likely to use narial geysering, which Dr Dwyer likens to “whales coming up to the surface and blowing a spurt of water up into the air”.
“The male crocodiles are doing this as a form of courtship with the females,” he said.
“It’s almost like singing a love song to the partner within their enclosures, prior to mating.”
Some of the sounds are non-vocal, with the crocodiles “using the head like a percussion instrument”.
“We’re finding the crocodiles are communicating a lot below the surface of the water as well,” Dr Dwyer said.
Adding AI to the toolkit
With more to uncover about the “mysterious” animals thorough bioacoustics, Dr Dwyer said future studies would examine how the apex predators used sounds in groups in their natural habitat.
“What we’re trying to do is really get a better idea of the behaviours of these animals — how they move, how they associate, their social networks, their ecology,” he said.
“We can then use that information to help inform government and conservation strategies on how to deal with these animals.”
