Leopards could reduce rabies by controlling stray dog numbers in India

Dog bites lead to perhaps 20,000 deaths from rabies each year in India, according to the World Health Organization.

Leopards are among the most widespread of all big cats, with a historical range covering large parts of Africa and Asia. Though humans have whittled away about 80 percent of that area, the big cats still overlap with some of the world’s largest concentrations of people. That convergence can be a recipe for conflict, but a recent study finds that leopards in India could be helping to keep people in India safe from rabies-laden dog bites.

“While leopards often conflict with people over livestock like cattle and sheep and are frequently persecuted throughout their range, we show that these unique predators can also be beneficial to human societies,” Christopher O’Bryan, an ecologist at the University of Queensland in Australia and co-lead author of the paper, said in a statement.

Stray dogs in Mumbai. Photo © Steve Winter/National Geographic.

Dog bites exact a heavy toll on people in India, leading to perhaps 20,000 deaths each year from rabies, according to the World Health Organization. O’Bryan and his colleagues were curious about whether Indian leopards (Panthera pardus fusca) had any influence on stray dog numbers in Sanjay Gandhi National Park, which sits in the midst of Mumbai. With more than 20 million people, Mumbai is the fourth-largest city by population in the world.

The team mined past studies for clues about what leopards living in the city park ate, and discovered that stray dogs made up about 40 percent of their diets.

Only about 41 leopards are thought to live in the park’s vicinity. But according to the researchers’ calculations, they appear to be remarkably efficient dog predators: The team estimated that leopards kill 1,500 dogs a year. Statistically, that means that people have to deal with 1,000 fewer bites, 90 of which could result in a rabies infection. The researchers published their findings on March 8 in the journal Frontiers in Ecology and the Environment.

“These results illuminate the need for more research on the impacts of predators on harmful pest species, such as feral dogs,” co-lead author and biologist Alexander Braczkowski said in the statement.

Previous research has looked at how predators impact ecosystems contained within protected areas, O’Bryan said.

“Case studies like that of wolves in Yellowstone National Park or mountain lions in Yosemite spring to mind, and these have shown that carnivores regulate everything from the numbers of prey to the healthy flow of water in rivers,” he said. “This new study is different in that it serves as a dramatic case study where a large carnivore lives alongside and is beneficial to people.”

Still, it’s important to account for both the benefits and drawbacks in areas where humans and large predators such as leopards overlap, the researchers cautioned.

“[It’s] equally important to assess the costs of these species to local communities, such as attacks on people,” they said in the statement. “The real challenge is navigating the costs with the benefits, and identifying those cases of net-benefit.”

Sanjay Ghandi National Park is home to around 40 leopards, living the midst of a city with a human population of nearly 21 million. Photo © Steve Winter/National Geographic.

Banner image of a leopard © Steve Winter/National Geographic.

CITATION

Braczkowski, A. R., O’Bryan, C. J., Stringer, M. J., Watson, J. E., Possingham, H. P., & Beyer, H. L. Leopards provide public health benefits in Mumbai, India. Frontiers in Ecology and the Environment.

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