Wednesday, December 03, 2014

Kill This Wolf and More Sheep Will Die, Study Suggests

http://www.nbcnews.com/science/environment/kill-wolf-more-sheep-will-die-study-suggests-n260826

By Miguel Llanos
Dec. 3, 2014

New scientific evidence published Wednesday could influence how gray wolves are managed in the Pacific Northwest — but it may not sway the decades-long debate over reintroducing the species to its native ranges in the region.

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It doesn't help that the conclusion of the new study sounds counterintuitive: Killing gray wolves in an attempt to reduce attacks on livestock can actually increase those attacks.

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Analyzing 25 years of wolf reports in Idaho, Montana and Wyoming, researchers found that killing one wolf increases the odds of depredations the following year by 4 percent for sheep and by 5 to 6 percent for cattle the following year.

In other words, killing 20 wolves in one year would double livestock deaths the next year, according to researchers at the Large Carnivore Conservation Lab at Washington State University.

How can that be? Killing a wolf likely disrupts that pack's social cohesion, study co-author Rob Wielgus tells NBCNews.com. The cohesion is established by an adult breeding pair that, while intact, can keep younger offspring from mating and reproducing earlier. Disrupt the cohesion, and sexually mature wolves that otherwise might have stayed in the pack longer may encourage them to go off and breed sooner, leading to more breeding pairs.

"When you kill the alpha male or alpha female you can fragment the pack and get increased breeding pairs," Wielgus says. "And that could lead to increased livestock depredation" because as those new pairs have pups they get tied to one place and can't hunt deer and elk as freely. That, in turn, leads them to hunt whatever is nearby, which can be easy prey like livestock, he says.

The increase happens up until 25 percent or more of a pack is killed, and at that point attacks do decline. But that's also when the population can be expected to crash, and that's not allowed under the federal delisting of wolves from the Endangered Species Act. First listed in 1974 after nearly being wiped out, the species was delisted in 2012 on condition that each state with a gray wolf population manage it properly.

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Wielgus acknowledges killing wolves can't be ruled out in every situation, but adds "let's use non-lethal preventative measures first."

Those include guard dogs, cowboy patrols, flags and spotlights. "If those fail," he says, "then go to lethal."

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