Study Casts Doubt on Theory That Legal Hunting Reduces Poaching
2016-05-11 14:16:09 GMT
"The study looked at wolves in Wisconsin and Michigan, states where the animals have at different times been placed under federal protection, removed from the endangered species list or relisted after court challenges. The federal flip-flopping, the researchers said, provided a natural experiment, allowing them to study the effects of policies that at points gave states the authority to kill, or “cull,” wolves suspected to have damaged property or threatened pets or humans."
"The study looked at an indirect measure — the rate of growth in the wolf population — to determine the extent of poaching and used a mathematical model to estimate the probability that the growth rate had changed as a function of the state’s culling policies. The researchers found that the growth rate declined to 12 percent from 16 percent in years when culling was allowed."
"But other scientists questioned whether Dr. Treves and Dr. Chapron had made their case. “Over all, I think this paper draws a bold conclusion from questionable evidence,” said Daniel MacNulty, a wolf expert and assistant professor of wildlife ecology at Utah State University. He said the authors’ estimates of the wolf population growth rate had so much uncertainty “that one can reasonably conclude that there is actually no meaningful difference between years with and without legal culling.” Tim Van Deelen, a wildlife ecologist at the University of Wisconsin, said that even if human-caused wolf deaths had increased, linking them to changes in policy was “too much of a stretch.” He offered other possible reasons for the slowdown in population growth that he said the authors did not adequately address, including reduced survival of wolf pups, decreased litter size, disease and increased territorial battles among wolves resulting in more deaths of juveniles or adults. And he and Dr. MacNulty said the authors had ignored some research that suggested that the growth in the wolf population in Wisconsin had slowed because of factors that accompanied the increase in their numbers."
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