They're gonna hear me roar: What do big cats' roars mean?
Dr Picture: The National Nyerere Park, Charlotte Searle Leopard Tanzania In
Birds, whales, and howler-monkeys are Nature’s great vocalists. Cicadas and crickets provide background music in balmy warm climes. Elephants, the double-bass players of the great animal orchestra, send sound vibrations through the ground — too low-pitched for us to hear. The love songs of frogs, like those of Chinese Opera, are an acquired taste. Nor do fish live in what the late Jacques Cousteau once claimed was a ‘silent world’. They too, it seems, can be a noisy lot. Relatively few wild creatures are completely silent or tone deaf.
Big cats produce intimidating roars. Are they just claiming to be the kings of the beasts, or is there more to their vocalisations than meets the ear? Do their utterances carry personal information?
Researchers from the University of Exeter have been eavesdropping on the utterance of wild leopards.
Mating partners can be difficult to contact. Forest dwelling birds, for example, can’t always see the wood for the trees. Without dating apps, lonely hearts must resort to the airwaves to get their amorous appeals out. A whale may be far away from its nearest potential suitor. But sound travels well in water — it’s claimed that some humpback songs can be heard up to 16,000km away.
Leopards face a similar problem. They may be the world’s most widely distributed big cats, and highly adaptive, but they remain solitary, elusive, and active mostly at night.
But what information must a message contain?
A hearer needs to know that it is a member of its own species that’s calling. Traditional formats and language must, therefore, be adhered to. Once the sender’s affiliation has been established, personal information about the caller, even a mini CV, might also be decoded.
But are big cats capable of such vocal sophistication? Can a leopard recognise the individual calling it? The Exeter team has been addressing such questions.
Gathering reliable data on a leopard’s secretive ways is notoriously difficult. The arrival of camera-traps, however, has changed that. But these cameras typically don’t record sounds, so the Exeter researchers had to come up with a cunning plan.
They set up 50 camera-traps across a 450km2 area of Tanzania’s Nyerere National Park. The traps, located where leopards were likely to wander, took pictures of creatures entering their field of view. A leopard has a unique pattern of rosettes on its pelage, so its identity can be established from a photograph.
To record sounds, microphones were installed close to each camera "so as to produce directly comparable acoustic and photographic data". The paired units did so "with 93% accuracy", the researchers claim. The systems remained active for 62 days in the autumn of 2023.
Both male and female leopards produce a ‘sawing roar’ — a complex pattern of low-pitched strokes. When the roars were bio-acoustically analysed, the results showed that, just like the robins in your garden, each leopard has its own unique ‘song’, readily identifiable to its neighbours. Audible more than a kilometre away, a leopard’s roar proclaims the caller’s identity and status, alerting potential mating partners and warning off same-sex intruders.