Repelling elephants, the noisy way


A male elephant charges towards unseen villagers after they threw stones in an attempt to scare away the herd of wild elephants in India. In Malaysia, the latest experiment to deter elephants, by using predatory sound playbacks, will be studied. Photo: AFP

A male elephant charges towards unseen villagers after they threw stones in an attempt to scare away the herd of wild elephants in India. In Malaysia, the latest experiment to deter elephants, by using predatory sound playbacks, will be studied. Photo: AFP


Sound recordings of angry predators may be used to stop elephants from raiding crops here, following breakthroughs in this method in India. The technique is being studied with the help of Indian professor Dr Vivek Thuppil, who had used it in south India.

Thuppil started researching the method in 2009 during his PhD studies on animal behaviour at the University of California, Davis. Together with Dr Richard G. Coss from the university, he used recordings of growls of tigers and leopards to mitigate crop-raiding by elephants. They used two sound-playback systems. The first is a wireless, active infrared beam system to explore the effects of night-time uncertainty. The second is a passive infrared motion detector-triggered system. The devices were installed in villages vulnerable to elephant raids.

The active infrared beam system was tested on 41 attempted raids. Of this, the sounds of tiger growls deterred 90% of the raids. For leopard growls, it was 72.7% and human shouts, 57.1%. Using the passive infrared motion system on 19 crop-raiding attempts, it was found that tiger growls deterred all of them while lion growls, 83.3%. Videos suggested that the elephants were more fearful of tiger growls than lion.

“Our results show that playbacks of threatening sounds can mitigate human–elephant conflict, and boost existing (mitigation) methods,” says Thuppil.

(In Malaysia, methods like translocation and electric fences have been used, while in other parts of Asia and Africa, elephant-proof trenches are commonly used against elephant raids).

Thuppil, who has been working at University Nottingham Malaysia Campus school of psychology since September, will study the use of the sound-based deterrent device in Malaysia under the research project, Management and Ecology of the Malaysian Elephant. The devices have not been installed in the field yet.

Despite its effectiveness against crop-raiding, the active infrared playback system has limitations for large-scale use. Thuppil says there were technical difficulties in setting up the infrared beams and wireless transmitters, as well as high maintenance cost given the short battery life. Subsequently, modifications were made for the system, in the form of an inexpensive passive infrared motion detector.

“Through this modification, the passive infrared motion sensors is the only part of the system and battery power for other components is activated for 30 seconds, triggered by movements of an approaching elephant. We found that power consumption reduced by 95%, with a single battery operating for 45 days straight,” says Thuppil.

He concludes that tiger growls are most effective in deterring elephants, but suggests that the sound playbacks be used with either electric fences or elephant-proof trenches.

“Right now, I’m in the midst of finding out how an elephant responds to threatening sounds that are not from a stationary source. I’m designing a new research project to test the effectiveness of a system where the speaker playbacks will be dynamic, like a simulator of a moving predator. For this purpose, there will be a network of speakers to continuously track the movement of an invading elephant, and the speaker nearest to the elephant will be activated. This new system will have a far greater range in application,” says Thuppil.

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Repelling elephants , the noisy way

   

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