Government-approved killing of wolves (pictured) increases illegal hunting in parts of the United States.
State-sanctioned culls are thought to be an effective conservation tool for reducing poaching of large carnivores. Guillaume Chapron at the Swedish University of Agricultural Sciences in Riddarhyttan and Adrian Treves at the University of Wisconsin–Madison studied wolf populations in Michigan and Wisconsin between 1995 and 2012. During that time, policy shifts meant that wolves experienced periodic stages of protection and legal culling. The authors found that population growth slowed during periods of culling, regardless of the number of wolves culled.
The authors ruled out other explanations for the decline, and suggest that culling increases people's intolerance of endangered predators, leading to more poaching. They recommend a moratorium on culling until its effects are better understood.