快猫短视频

Crocodile roars 鈥� and moos 鈥� could help conservationists monitor populations of species that are hard to track through visual surveys.

The big-eyed, tiny-bodied African dwarf crocodile (Osteolaemus tetraspis) prowls the dense forests and narrow streams of West Africa. But the species is very hard to spot and extremely difficult to count. 快猫短视频s assume that it is quite common, however, because the tiny crocodiles show up in the bushmeat trade a lot.

鈥淭here鈥檚 still enough of them to be caught and sold, but that also means there鈥檚 probably quite a big conservation threat for them,鈥� says at the Adam Mickiewicz University, Poland. 鈥淚t鈥檚 a species that really nobody knows about.鈥�

Staniewicz鈥檚 team wondered whether they could find out more about the elusive creature using sound. They recorded 97 vocal signals from a pair of captive O. tetraspis housed at Bristol Zoo Gardens in the UK. Analysing the recordings revealed that the species produces vocal 鈥渄rums鈥�, 鈥渞umbles鈥� and 鈥済usts鈥� unlike anything produced by other crocodylids, members of the crocodile family. The gust sounds like a howling wind:

鈥淭hese lower frequency sounds, you can kind of hear them as sort of pulses, and they鈥檙e barely on the range of human hearing,鈥� says Staniewicz.

The tiny crocodiles also produce a sound uncannily reminiscent of a cow鈥檚 moo:

This is virtually unheard of among crocodylids, according to Staniewicz 鈥� although one species of Chinese alligator may .

The researchers then compared their 97 vocal signals to 201 mystery sounds that had been recorded during an unrelated elephant conservation project in Gabon. The analysis confirmed the unidentified sounds were actually O. tetraspis.

Recording their vocalisations could help conservationists track the crocodiles in the wild remotely using microphones, says Staniewicz. But more research is needed to capture their full repertoire of sounds 鈥� and those of other crocodylids around the world 鈥� to understand whether the different calls correspond to different individual crocodiles.

at Lund University in Sweden, who was not involved in the study, is working on such a project now.

鈥淲e need to do a bit more. We need more recordings,鈥� says Reber. 鈥淪o maybe it鈥檚 not feasible yet to do it, but it鈥檚 a step towards it. And if it works, yes, it鈥檚 very useful.鈥�