R.ebounding populations of gray wolves (wolf) in Wisconsin are linked to reduced deer auto accidents, researchers have found. These predators often visit certain routes or travel corridors that include man-made roads, and the authors conclude that the wolves did the humans a favor by keeping the deer away. According to the study, published online May 24 in PNASIn counties where wolf populations returned after extinction in the mid-20th century, deer vehicle accidents decreased an average of 24 percent, saving the state nearly $ 11 million annually.
“The icing on the cake is that wolves do this job at their own expense all year round,” says Liana Zanette, an ecologist at Western University in Canada who was not involved in the study The Atlantic. “It all seems to be a win-win situation for these wolf circles.”
As wolves frolic on roads, trails, and pipelines that have been conveniently cleared by humans, they keep prey from hanging around, the new study authors suggest. And, of course, wolves eat deer, directly reducing the number of deer on roads, although this seemed to explain only about 6 percent of the drop in deer-vehicle collisions documented by the team. Overall, counties with wolves had 38 fewer collisions with deer vehicles per year by the end of the study period.
Study co-author Jennifer Raynor, a natural resource economist at Wesleyan University, reports Science news that there are other potential benefits of wolves, such as reducing Lyme disease transmission with fewer deer herders not treated in the study.
The importance of predators is well recognized, to the point that some regions of the US and the world have reintroduced the animals. For example, gray wolves were brought back to Yellowstone National Park in the mid-1990s to help restore an ecosystem devastated by elk herbivores. The idea of introducing wolves to places with larger human populations like Wisconsin is controversial, but some states like Colorado are considering it.
The benefit of reducing deer collisions was suggested in a 2016 study that estimated pumas in the eastern United States could help reduce accidents by about 22 percent. The wolf study “adds to a growing awareness that scientists should consider both the costs and benefits of large carnivores in the landscape,” said Adrian Treves, a conservation biologist of the University of Wisconsin, who did not participate in the research, told the Associated Press.