US – Killing wolves to reduce livestock losses does not work, says a study looking at 25 years of government control data.
Likelihood of livestock deaths double if 20 wolves are killed, according to Washington State University researchers analysing data collected in Montana, Wyoming and Idaho.
The PLOSE ONE study found that killing one wolf results in a four per cent rise in sheep deaths, with 5-6 per cent more cattle dying.
Odds of sheep deaths rise four per cent if one wolf is killed, and cattle rise six per cent.
The study, the largest of its kind, said the trend ran until 25 per cent of wolves had been killed, at which point conservationists see a “standing wave of livestock depredations.”
Lead author, wildlife biologist Rob Wielgus, said similar trends had been seen in cougars.
"The only way you're going to completely eliminate livestock depredations is to get rid of all the wolves," he said. "Society has told us that that's not going to happen."
Reintroducing wolves is controversial, with much debate over what constitutes a stable population.
When wolves are shot, social structures are broken in the pack as breeding pairs are broken up, liberating sexually mature wolves that would otherwise be prevented from mating by adult pairs.
These animals then have pups, becoming bound to locations, making wild prey a bigger challenge and livestock an easier alternative, explained Mr Wielgus.
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