The scientists, who published their results in the December edition of Conservation Biology, compared the effectiveness of non-lethal methods for keeping large carnivores away from human structures, livestock, and other potential conflict areas. They found that motion-activated lights and sounds can keep both large- and medium-sized predators away from food sources, thus preventing a clash that can result in large carnivores being destroyed.
"In wealthy countries such as the United States, non-lethal repellents such as motion-activated guards can help resolve human-carnivore conflicts without destroying animals that perform important ecological roles" said Dr. Adrian Treves, a conservationist with WCS's Living Landscapes program and co-author of the study. "We need better methods and we need to consider human behavior as part of the problem--limiting the accessibility of food sources whether its garbage, crops or livestock."
In the study, conservationists tested the non-lethal repellent methods in six wolf territories in Wisconsin (which also contained black bears and other predators). The study found that motion-activated devices, with strobe lights and 30 random noises, were effective for keeping predators away from deer carcasses at the study sites, including bald eagles, wolves, vultures--and black bears. Fladry--a wolf management method from Eastern Europe using flags on fences--may be moderately effective in repelling wolves, but not bears.
"High-technology devices are much more expensive, complicated, and limited in effectiveness than a single bullet from a high-powered rifle, but they also allow a predator to live--surely the goal of conservation," states Dr. John Shivik, of Wildlife Services' National Wildlife Research Center and Utah State University, the lead author of the study. Other authors included Peggy Callahan of the Wildlife Science Center.
In a comparison with methods on captive wolves, motion activated guards rated higher than electronic training collars--similar to the "invisible fence" collars used to keep domesticated dogs on home properties. Some wolves simply tolerated the mild electronic shocks and continued to feed
"There is no single solution for every situation but individuals and communities should be given a variety of options so they can tailor their responses to their needs and tolerances," Treves said. "Non-lethal deterrents can now be offered as one option."
Journal
Conservation Biology