Conservation requires accurate information about species occupancy, populations and behavior. However, gathering these data for elusive, solitary species, such as leopards (Panthera pardus), is often challenging. In a large-scale paired camera trap and autonomous recording survey in Nyerere National Park, Tanzania, scientists found that each leopard has its own unique roar through which it can be identified. The authors were able to identify individual leopards by their vocalizations with 93.1% accuracy.
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An example of an autonomous recording unit (left) and camera trap (right) station. Image credit: Growcott et al., doi: 10.1002/rse2.429.
Leopards are listed as Vulnerable 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 kilometer away, used primarily to attract mates and for territorial defense.
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.
University of Exeter Ph.D. student Jonathan Growcott and his colleagues conducted the first, large-scale paired passive acoustic monitoring and camera trapping survey.
They focused on a 450-km2 expanse of 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 modeling system to analyze 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.
“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,” Growcott said.
“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 vocalizations 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 study was published this month in the journal Remote Sensing in Ecology and Conservation.
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Jonathan Growcott et al. The secret acoustic world of leopards: A paired camera trap and bioacoustics survey facilitates the individual identification of leopards via their roars. Remote Sensing in Ecology and Conservation, published online December 22, 2024; doi: 10.1002/rse2.429
