Each leopard has its own unique roar through which it can be identified, a new study finds.
In the first large-scale paired camera trap and autonomous recording survey for large African carnivores, researchers were able to identify individual leopards by their vocalisations with 93% accuracy.
It has been hailed as an important first step towards using bioacoustics in the conservation of leopards.
Leopards are listed as 'vulnerable' to extinction according to the IUCN Red List of Threatened Species mainly due to habitat loss and human-wildlife conflict.
But because leopards are solitary, nocturnal creatures that live across huge expanses of terrain, scientists struggle to gather reliable data that would help them reverse population declines.
There is little scientific research about the 'sawing roar' of a leopard – a repeated low-frequency pattern of strokes, often audible from at least a kilometre away, used primarily to attract mates and for territorial defence.
But studying leopards through the sounds they make – a technique known as bioacoustics and more typically used to monitor birds and marine species – would have the advantage of allowing researchers to monitor much larger areas.
It could lead to more complex studies such as population estimates, a key metric for helping policymakers and conservation practitioners understand how to manage landscapes and mitigate human-wildlife conflicts.
The research team conducted their study across a 450km2 expanse of the Nyerere National Park in Tanzania, where they attached 50 pairs of cameras to trees along roads and trails.
They placed microphones next to each camera so that they could identify the leopard from the camera and then extract the roaring bouts from the audio.
They then used a modelling system to analyse the temporal pattern of a leopard's roar, and found individual identification was possible, with an overall accuracy of 93.1%.
The study shows that using multiple forms of technology to record complementary data can exploit a wider variety of species traits than single technology studies alone.
Lead author Jonathan Growcott, a PhD student at the University of Exeter, said: "Discovering that leopards have unique roars is an important but fundamentally quite basic finding that shows how little we know about leopards, and large carnivores in general.
"We hope it will allow leopards to become the focus of more acoustically complex science such as population density studies and open the door to more work on how large carnivores use vocalisations as a tool.
"Importantly, our success in using a combination of different types of technology could hopefully lead others to think about how to integrate different types of technology into their research, as the rich data this provides could really push science ahead and help us understand ecosystems and landscapes in a much more holistic way."
The research was a collaborative effort between the University of Exeter, the Wildlife Conservation Unit at the University of Oxford, Lion Landscapes, Frankfurt Zoological Society, TAWIRI (Tanzania Wildlife Institute for Research) and TANAPA (Tanzania National Parks Authority), as well as computer scientists from Exeter and Oxford.
It was presented by Growcott at the British Ecological Society Annual meeting in Liverpool earlier this month, an event which brought together 1,500 ecologists.
Hazel Norman, CEO of the British Ecological Society said: "This study showing that individual leopards can be identified and monitored just through their roars is a brilliant example of how ecologists are applying novel ideas and technologies to uncover fascinating new insights into our natural world.
"Jonathan presented this research at our recent British Ecological Society Annual Meeting in Liverpool, which is a brilliant forum for ecologists to share their research and ideas with the ecological community and beyond."
" The secret acoustic world of leopards: A paired camera trap and bioacoustics survey facilitates the individual identification of leopards via their roars " is published in Remote Sensing in Ecology and Conservation.
