Study: Noise Machine Keeps Predators Off Property

John Pickrell
for National Geographic News
January 13, 2004

Conservation scientists may have hit upon the 21st century's answer to the good old-fashioned scarecrow. A motion-activated device which blasts out a cacophonous chorus of gunshots, helicopters, and other sounds, together with blinding flashes of strobe lighting, may be a highly effective tool in repelling wolves, bears, and other large carnivores.

The fright device could be a valuable new tool in fighting the escalating problem of human-carnivore conflict, suggest conservationists behind a new study confirming its effectiveness. Currently when coyotes, mountain lions, and other predators threaten livestock, U.S. federal wildlife managers are forced to kill them.

"To promote the existence and expansion of large carnivores, conservation biologists should assist with the real world problems predators cause," wrote the conservationists in the current issue of the science journal Conservation Biology.

New Tool

Shooting predators is an often used—and not always effective—solution to stopping the predation of livestock and pets in rural regions of the United States, but this practice damages efforts to restore rare carnivore populations.

"We're hoping to give communities, landowners, and wildlife managers another tool in their kit other than traditional lethal control," said study co-author Adrian Treves at the Wildlife Conservation Society in New York City.

Established non-lethal deterrents include electric fences, trenches, and walls, and guarding sheep and cattle with dogs and people. Few landowners supervise their flocks as shepherds once did, but now many farmers in the western U.S. have completely dispensed with barriers. "The elimination of many large predators made it possible to reduce reliance on these methods," said Treves.

However, as wolf conservation efforts and others pay off in terms of rising numbers of reintroduced animals, farmers may need to consider protecting their livestock again, and no longer rely on removal of predators.

With this in mind, study author John Shivik of the Wildlife Services' National Wildlife Research Center in Fort Collins, Colorado has developed the infra-red activated device for deterring predation of livestock.

Other devices, which randomly activate lights and sirens, have been effective as deterrents, but carnivores (especially bears) may quickly learn they pose no real threat. Shivik's fright device not only activates as an animal approaches, but also produces a random selection of 30 people-related sounds, including gunshots, yelling, vehicles, glass breaking, helicopters, and dogs barking. Because the device is only set off when animals approach human property boundaries, they become used to it more slowly.

Acid Test

To test the effectiveness of the device at dissuading predators from feeding, Treves, Shivik and colleagues set up three study plots in each of six Wisconsin wolf (Canis lupus) pack territories. They placed road-killed deer carcasses in roped-off plots that were either unguarded, rigged with yellow flagging, or linked up to a motion-activated fright device.

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