When leopards stray into a city, people often fear them because of the danger they pose. But it turns out these big cats could be valuable neighbours: by preying on feral dogs in Mumbai, they are reducing the risk of people catching rabies.
About 20,000 people die of rabies in India every year. Feral dogs are the main source, as they bite people and pass on the rabies virus.
Christopher O’Bryan and Alexander Braczkowski at the University of Queensland and their colleagues compiled existing data on the diet of leopards living in Sanjay Gandhi National Park, on the edges of Mumbai. They found that 40 per cent of the average leopard’s diet consists of feral dogs.
All told, the 35 leopards in the park probably eat 1,500 dogs per year. Given how often the dogs bite people and how many of them have rabies, the leopards’ kills are preventing about 1,000 bite incidents per year – and 90 potential rabies cases.
“This study is a striking example of a large carnivorous animal providing a direct benefit to humans,” says O’Bryan.
The same could be true of other leopard populations that encroach on cities. The team found 19 studies describing leopards eating feral dogs in Asia and Africa. However, O’Bryan says that they would need to be studied more closely to be sure that they bring the same benefit.
The researchers also emphasise that leopards can cause harm. In particular, they often kill livestock – leading people to persecute them.
“It’s difficult to weigh up the costs with the benefits with a large cat species that’s known to attack and even kill humans,” says O’Bryan. “We just want to provide an angle that hasn’t been explored before, despite the pieces of the puzzle being in front of us the whole time.”
Journal reference: Frontiers in Ecology and the Environment, DOI: 10.1002/fee.1776
(First published online by New Scientist. Available online at: https://www.newscientist.com/article/2163166-leopards-that-live-in-cities-are-protecting-people-from-rabies/)