Killing Wolves To Protect Farm Animals Backfires

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In October, a Washington farmer spotted a wolf, pursued the animal for several miles, then shot him. The wolf's fatal mistake? Being seen near a farm.

Not only is killing endangered species a crime, but it's also not an effective way to protect sheep or cattle. In fact, when farmers kill wolves, the plan usually backfires - newly fragmented wolf packs claim more livestock in the long run, according to a new study. For each wolf killed, the odds that other wolves will prey on nearby farm animals actually increase.

Looking at a quarter century's worth of data collected by the U.S. Fish and Wildlife Service's annual wolf reports, scientists were able to track how many wolves were killed legally. By pairing this information with livestock statistics from the U.S. Department of Agriculture, the researchers could examine the link between culling wolves and the rate at which these predators attacked livestock.

Washington State University biologist and study author Rob Wielgus wasn't sure if killing wolves would help to save livestock. Last year, Wielgus and his colleagues had found that culling cougars resulted in more, not fewer, livestock deaths - evidence that killing these animals was senseless.

Killing wolves, it turns out, is also senseless, as it fails to protect livestock to a surprising degree. With the death of a single wolf, cattle and sheep deaths bump up the next year by about 4 percent. Kill 20 wolves, and livestock are twice as likely to be killed. It's not that wolves are bound by some sort of canine revenge code; instead, as Wielgus and WSU environmental scientist Kaylie Peebles reported Wednesday in the journal PLOS ONE, the death of a wolf can fragment a pack, causing smaller groups of wolves to disperse. If the immigrant wolves settle and have pups near livestock, they're more apt to attack the farm animals, rather than straying away to chase down elk or deer.

This upswing increases until about 25 percent of the wolf population is slain - an unsustainable scenario, at odds with a goal of reintroducing wolves to their former habitat. "The only way you're going to completely eliminate livestock depredations is to get rid of all the wolves," Wielgus said, "and society has told us that that's not going to happen."

When it comes to killing sheep and cattle, it's worth bearing in mind that the role wolves play is much more cameo than lead: For every 1,000 livestock who perish, wolves account for about one to six deaths. It's understandable that ranchers want to protect their animals, so Wielgus would like to see more nonlethal options, such as fences, alarms and other deterrents, which have been proven to be effective measures in "no-kill" wolf country like Oregon.