Why would predation increase after predators are killed? When pack animals such as coyotes, dingoes and wolves are killed, the social structure of their packs breaks down. The review found that nonlethal methods generally reduced livestock predation more effectively, and that predation actually temporarily increased after use of some lethal methods. Nonlethal methods included fladry, guard animals, chemical repellents and livestock protection collars. Lethal methods ranged from civilian hunts to government culls. One 2016 analysis reviewed studies that compared lethal and nonlethal strategiesfor controlling livestock predation. Other research indicates that even if predation is one factor in ranchers’ economic losses, lethal control is not the best way to reduce it. She found that variables including the price of hay, wage rates and the price of lamb explained most of the decline, and that the amount of money spent on predator control had little effect. Kim Murray Berger, who was then a research biologist with the Wildlife Conservation Society, built and tested a series of statistical models to explain the declining number of sheep being bred in the United States. However, a widely cited 2006 study called coyotes scapegoats for factors that were more directly related to the decline of sheep ranching in the United States. It is understandable for struggling ranchers to blame coyotes for economic losses, since kills leave tangible signs and killing predators seems like a logical solution. Early this year the American Society of Mammalogists called for more scientific scrutiny of the policy of killing large predators. Scientists have also criticized WS for unintentionally killing numerous animals and birds, including federally protected golden and bald eagles, while failing to do any studies of how its actions affected nontarget species. M-44s killed more than 1,100 domestic dogs between 20. To keep coyotes in check, WS employees set neck snares and other traps, shoot coyotes on the ground and from planes and helicopters, arm sheep with collars containing liquid poison and distribute M-44 “bombs” that inject sodium cyanide into the mouths of animals that chew on them.Īs in warfare, there is collateral damage. External review would be useful because even experienced ranchers may have trouble determining in some cases whether a sheep was killed by a coyote or a dog (dogs are second only to coyotes in reported predation on livestock), or died from other causes and later was scavenged by coyotes. Importantly, however, these numbers were based on self-reported data and were not verified by wildlife professionals. Of those animals, ranchers stated that 33,510 adult sheep (more than half of total predation losses) and 84,519 lambs (nearly two-thirds of all predation losses) were killed by coyotes.Īccording to the American Sheep Industry Association, about UD$20.5 million of ranchers’ losses in 2014 (roughly one-fifth of their total losses) were attributed to coyotes. Twenty-eight percent of adult sheep losses and 36 percent of lamb losses were attributed to predators. In a 2015 USDA report on sheep losses, ranchers reported how many of their animals died in 2014 and how they died. The most common reason for killing coyotes is to reduce predation of livestock, such as sheep and calves. Nonetheless, their range has expanded from the western plains across most of the continent. Warfare on the rangeĬoyotes have been a target ever since European explorers first arrived in their territory centuries ago. As a conservation biologist specializing in human-wildlife conflicts, I see growing evidence that it is time to reconsider lethal control. At the same time, research shows that predators play key roles in maintaining healthy ecosystems. In fact, it can even make the problem worse. However, there is no clear evidence that lethal control works to reduce human-predator conflict. But every year it also kills tens of thousands of predators, including bears, bobcats, coyotes, foxes, hawks, cougars and wolves. WS uses nonlethal techniques, such as livestock guard dogs and fladry-hanging strips of cloth from fences, where they flutter and deter predators. Its mission is to “resolve wildlife conflicts to allow people and wildlife to coexist.” This broad mandate includes everything from reducing bird strikes at airports to curbing the spread of rabies.Ĭontrolling predators that attack livestock is one of the agency’s more controversial tasks. The responsible agency was Wildlife Services (WS), part of the U.S. The following essay is reprinted with permission from The Conversation, an online publication covering the latest research.įew Americans probably know that their tax dollars paid to kill 76,859 coyotes in 2016.
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