How do you scare off a hungry elephant? With a hungry tiger, of course. In the farming towns of southern India, elephants are agricultural pests, thanks to their nighttime raids on crop fields. Farmers typically try to prevent elephant raids with electric fences and trenches. But such tactics aren't foolproof, and when they fail, humans or elephants can be killed. In a new study, researchers tested whether audio recordings of threatening sounds—human shouts and leopard and tiger growls—would keep the ravenous beasts at bay. Tigers are known to prey on elephant calves, but leopards usually aren't natural predators. The researchers used a system of infrared detectors to sense elephants heading toward farmers' fields. When the animals tripped the system, as did the hapless elephant in the video above, it triggered playback of a recording of a roaring cat or angry humans. Over 41 attempted raids, tiger sounds deterred 90% of elephants, whereas leopard and human sounds deterred 73% and 57% of elephants, respectively, scientists report online this month in Oryx. But an elephant never forgets, so those that encountered the noises more than once—without seeing their foe—were less likely to be fooled. The researchers tested two infrared systems, one that was more complex and realistic, and one that was simple enough for farmers to set up around their fields. Both were effective in deterring elephants. The researchers suggest that the system could work well in combination with currently used methods.
(Video credit: Vivek Thuppil and Richard Coss)