NAIROBI, Kenya — Leopards often produce a unique, deep, guttural roar commonly described as “sawing” due to its resemblance to the sound of a person sawing wood by hand.

Researchers in a study published in the journal of Remote Sensing in Ecology and Conservation have found that studying these sounds, using a technique known as bioacoustics, allows monitoring of much larger areas. Bioacoustics explores how living organisms produce, transmit, and receive sounds in their environment.

By monitoring larger areas, researchers can capture details from a large number of animals, thereby building a more compelling database than if just a handful of animals were studied, according to the report.

One of the study authors, Jonathan Growcott, a Ph.D. student at the University of Exeter, U.K., says the findings are “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 from habitat loss due to agricultural land expansion or grazing areas and human-wildlife conflict.

But because leopards are solitary, nocturnal creatures living 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,” Growcott says.

The team paired camera trap ― an infra-red camera that can take photos or videos of animals as they move past ― and autonomous recordings for the survey of large African carnivores in Nyerere National Park in Tanzania, in which they were able to identify individual leopards by their vocal sounds with up to 93% accuracy.

They placed microphones next to each camera so they could identify the leopard from the camera and then extract the roaring bouts from the audio.

They analyzed the temporal pattern of a leopard’s roar and found individual identification was possible, with an overall accuracy of 93.1%.

According to the researchers, using multiple forms of technology to record complementary data can exploit a wider variety of species traits than single technology studies alone.

Growcott says the findings could also 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 rich data this provides could push science ahead and help us understand ecosystems and landscapes in a much more holistic way,” Growcott says.

“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,” he adds.

William Leekoolol, a member of the Mara Conservancy in Kenya, says communities living in close quarters with the animals understand the traits explained in the study.

“We know these sounds by leopards and we also know when and why they make them,” says Leekoolol, who is a village elder and a local conservationist in Shompole, in Kajiado county, southern Kenya.

According to Lekoolol, the leopards make such sounds during the mating season, adding, “The animals are fierce during this time and would easily attack humans if approached.”

He says that the Maasai community has for centuries utilized this Indigenous knowledge to help conserve leopards by avoiding encroachment on their territories during mating season.

Hazel Norman, the CEO of the British Ecological Society, says, “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.”

Paolo Strampelli, a conservationist from the department of zoology, University of Oxford, who did not participate in the study, says reliable population monitoring is an essential component of any wildlife conservation program.

“But it can be especially challenging for large carnivore species such as leopards due to their secretive nature and naturally low densities,” he says.

He notes that established methods for assessing how leopard populations are doing involve identifying individuals from camera trap photos based on their unique spot patterns.

“By showing that individual leopards can also be identified based on their unique roars, this study suggests that acoustic monitoring could potentially be a useful tool for monitoring leopards in the future,” Strampelli says.

“This could be especially valuable in areas where camera traps may not be suitable, such as those where there is a high risk of theft, or as part of a wider biodiversity monitoring effort that is also interested in insects, birds and other sound-producing species,” he adds.

Banner image : Leopards often produce a unique, deep, guttural roar commonly described as “sawing” due to its resemblance to the sound of a person sawing wood by hand. Image by Birger Strahl via Unsplash.

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Citation

Growcott, J., Lobora, A., Markham, A., Searle, C. E., Wahlström, J., Wijers, M., & Simmons, B. I. (2024). 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.doi:10.1002/rse2.429