Lives could be saved and crops protected by playing sounds of growling tigers to wild elephants on their way to raid fields in India, a study reports. There have been hundreds of deaths and much crop loss in the last decade in areas where elephants come into contact with people.
The study, published in the current edition of Biology Letters, looked at the night time behaviour of elephants, and particularly their reaction to 'aggressive' tiger and leopard growls, in villages bordering two animal reserves in the Indian states of Karnataka and Kerala.
"Studying elephant behaviour at night is extremely risky," says lead author Vivek Thuppil, an animal behaviourist at the University of California, Davis, United States.
According to a paper in Gajah, the journal of the Asian Elephant Specialist Group (AsESG), 226 people and 87 elephants have died in clashes between 2003 and 2009.
To avoid such danger, Thuppil positioned infrared beams on paths usually taken by the elephants on their routes to crops. When elephants crossed the beams they triggered a playback of a recording of either tiger or leopard growls.
Analysis of movement showed that elephants retreated quickly and silently on hearing the tiger growls. But the calls of leopards — which, unlike tigers, do not prey on young elephants — prompted the elephants to linger in the area while trumpeting and grunting aggressively.
Thuppil says that if tiger growl playbacks are deployed continuously during crop growing they could prevent elephants raiding fields. He adds that the loudspeakers could also warn villagers of invading elephants — potentially avoiding dangerous contact.
Other experts are not sure if this approach will succeed in the long run.
"Many such experiments on predator call replay have been tried on elephants, but the primary drawback is that elephants ultimately realise the hoax," says Sushant Chowdhury, a senior scientist at the Wildlife Institute of India. The paper says, however, that most of these studies explored the behaviour of African elephants during the day. In contrast the nocturnal behaviour of Indian elephants is poorly understood.
Prajna Chowta of the Aane Mane Foundation, an Asian elephant conservation agency, agrees with Chowdhury. But she says that given the lack of other methods to deal with the problem it is worth trying.
She also points out that a system may not be easy to power and maintain in isolated rural areas. Thuppil says that he has used rechargeable batteries topped up by solar panels, which could make the approach sustainable.
• Link to abstract in Biology Letters
• Link to the paper in Gajah