A new study has confirmed that African lions produce two distinct roar types: the well-known full-throated roar and what researchers are calling an 'intermediary roar'.
The finding, made with the help of artificial intelligence (AI), marks a major advance in bioacoustics and could help with future conservation efforts, say scientists from the University of Exeter, who published their findings in Ecology and Evolution.
Listening to lions
Lions are listed as vulnerable on the International Union for Conservation of Nature (IUCN) Red List. There are estimated to be between 23,000 and 39,000 African lions remaining in the wild, though new data suggests that the population may be closer to 20,000, with their numbers dropping significantly in the past 25 years, according to the World Wildlife Fund (WWF).
Being able to reliably recognise individual animals through sound could provide an important new tool for conservationists working across vast and often inaccessible landscapes, says the study's lead author Jonathan Growcott from the University of Exeter.
“Lion roars are not just iconic – they are unique signatures that can be used to estimate population sizes and monitor individual animals," says Growcott.
"Until now, identifying these roars relied heavily on expert judgment, introducing potential human bias. Our new approach using AI promises more accurate and less subjective monitoring, which is crucial for conservationists working to protect dwindling lion populations,” adds Growcott, who says this is the first time AI has been used to automatically distinguish between roar types.
Using machine learning, the researchers created an automated system that classifies calls with a 95.4% accuracy.
According to the study, the lions’ roaring naturally contained both a full-throated roar and a newly described ‘intermediary roar’, suggesting the big cats have two distinctive roar types instead of one (as was previously thought). Similar findings have been observed in other large carnivores, such as spotted hyenas.
The team believes the technique offers a simpler and more reliable alternative to traditional monitoring tools such as camera traps or spoor (track and scent) surveys.
“We believe there needs to be a paradigm shift in wildlife monitoring and a large-scale change to using passive acoustic techniques," says Growcott. "As bioacoustics improve, they’ll be vital for the effective conservation of lions and other threatened species.”
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