But a new study, published Monday in the Proceedings of the Royal Society B, challenges that long-held theory. It examined 17 years of back-and-forth wolf management policies and used complex mathematical modeling to conclude that state-sanctioned culls in Wisconsin and Michigan have actually led to more poaching.
If that sounds like heavy reading, the authors also put together a more accessible explainer: A video starring Lego-like Playmobil figurines. To the narration (in heavily accented English) of French co-author Guillaume Chapron, the little plastic guys, gals and wolves act out the intermittent periods of federal protection for wolves, culling and court rulings on the issue. Tiny ranger-looking fellows lift shotguns, the sound of gunfire booms, and the wolfpacks topple.
The video is a little silly and strange, but co-author Adrian Treves said the point it makes has very serious implications for government wildlife authorities, who, he said, have not used science to back their support for culling “problem” wolves, which are managed differently from state to state. The U.S. Fish and Wildlife Service has also argued in its current proposal to delist Yellowstone grizzly bears that killing some bears will protect them from poaching.
“We’ve got a problem currently in wildlife management by the agencies: It’s the reliance on anecdote and a kind of ‘trust me’ attitude,” Treves said. “I’m sorry, that sort of ‘trust me’ attitude doesn’t work.”
Treves, a conservation biologist at the University of Wisconsin-Madison, and Chapron, an ecologist at the Swedish University of Agricultural Science, looked at gray wolf populations in Wisconsin and Michigan between 1995 and 2012. Wolf management policies changed often during those years, so the researchers could compare periods when culling of wolves was allowed to those when it wasn’t.
They found that the wolf population growth rate slowed by 25 percent during culling periods, Treves said. He said the study eliminated several possible explanations, including wolf migration or reduced breeding. The culls themselves also didn’t kill very many wolves, he said. That led them to conclude the cause was illegal killings — which are not tracked — probably because authorities sent a “signal” to the public when they allowed culling.
“The signal being something like: Wolves are lower in value, or wolves are out of control,” Treves said. “And it seems like the poachers get the message, okay, I can help [control wolves] now, or I’m less likely to get busted for poaching.”
The finding, he said, should prompt a moratorium on culling as it’s currently implemented. Treves said it should be used only when there’s “an imminent threat to human safety,” which, he said, is “exceedingly rare.”
The study is likely to fuel debate over wolf management in the United States, which is already a very controversial topic involving federal and state wildlife managers, scientists, conservationists, Native Americans, ranchers and even pet owners.
L. David Mech, a wolf expert and biologist for the U.S. Geological Survey, said he has heard ranchers and farmers say “over and over again” that having permission to defend livestock from wolves would lead to a decrease in poaching. That’s anecdotal evidence too weak to build a policy on, he said.
But Mech said he was not convinced that the new study is stronger, because it didn’t base its conclusions on poaching data but rather by eliminating other possibilities for lower wolf population growth. He added that wolf culls have not harmed populations in other states.
“On one side, we have this information that’s anecdotal but weak, and on the other side we have some inferences that are based on some data but not direct empirical data, and that’s weak,” Mech said. “So we’re left with nothing really definitive yet.”
Jeremy Bruskotter, an associate professor at Ohio State University’s school of environment and natural resources, said he thought the authors did “due diligence” in considering and dismissing other potential reasons wolf population growth dropped. The study’s conclusions appear to be strong for Wisconsin and Michigan, he said.
But it’s not clear that culling would have the same effects elsewhere, Bruskotter said.
“How applicable is that to Norway or Spain or another country or another animal?” said Bruskotter, who studies human-wildlife conflict and wildlife management. “The government is going to be perceived differently, the policy is going to be perceived differently, even predators are going to be perceived differently.”
Bruskotter agreed with the authors, however, that the U.S. Fish and Wildlife Service has often failed to deeply evaluate the effects and public perceptions of their policies.
“They don’t have psychologists and sociologists and anthropologists on their staff, and I think what we’re seeing increasingly is that the threats to species ultimately reside with human behavior,” Bruskotter said. “What goes on in people’s minds is very relevant.”