Treves and Capron studied wolves in Michigan and Wisconsin between 1995 and 2012, a period when the animals were taken off the US Endangered Species List in both states and culling was occasionally allowed.They discovered that wolf populations grew, but around 4 percent less in years when culling occurred. In years when hunting was permitted, the wolf populations grew by 12 percent, compared to 16 percent growth when the wolves were left on their own."When the government kills a protected species, the perceived value of each individual of that species may decline; so liberalizing wolf culling may have sent a negative message about the value of wolves or acceptability of poaching," the researchers wrote in the study.Related: Animal Rights Activists Target Wisconsin's Annual Grey Wolf Hunt
Wolf population history in Wisconsin (top) and Michigan (middle) and policies (bottom). The black squares are FWS population counts (scale on left axis, minimum and maximum for Wisconsin, minimum for Michigan), the grey area is the 95 percent credible interval of the fitted population model, the histogram shows the number of wolves culled (scale on right axis). The bottom panel shows the proportion of each year in which culling was allowed (or not). Some wolves were killed legally when culling was not allowed (e.g. year 2011) because the FWS allows killing individuals of an endangered species 'to protect himself or herself, a member of his or her family, or any other individual from bodily harm' (ESA §11(a)(3)).
Critics have said Treves and Capron's findings were inconclusive because they looked at the wolves' growth rate, not the amount of animals that were poached. "It's an inference," US Geological Survey wolf expert Dave Mech told the Minneapolis Star Tribune. "It's only as strong as that."It wouldn't be easy to satisfy those critics, Treves countered. A tally of wolf carcasses would be great data, "but poachers don't turn over evidence," he said.Advocates are already citing the study in the big battle brewing over the FWS move to delist bears in the Yellowstone region."We hear over and over that individual wolves have to die in order to placate a wolf-hating public and prevent illegal killing — but this shows that to decrease poaching, the government should send the message that wolves have a high public value," said Michael Robinson of the Center for Biological Diversity in a statement.It's not clear if agencies would take the study into consideration.
Follow John Dyer on Twitter: @johnjdyerjrPhoto via FlickrRelated: Hunters Descend on Southern Florida for Annual Python Hunt