Anyone who has gone on a road trip is familiar with the sight of roadkill on the side of the highway, but in some areas, this problem is more pronounced than others. For example, deer were being killed regularly along the roads in Michigan’s Upper Peninsula, but that all changed when the state reintroduced wild wolves. 

When gray wolves from Canada and Minnesota were brought back to the area, vehicle collisions involving deer went way down. Researchers from the University of Wisconsin quantified these results and found that once wolves colonize a county, deer-vehicle collisions go down about 24 percent. 

When wolves return to an area, they keep the deer populations at stable levels, in turn providing benefits for entire ecosystems and the humans that drive through them. A study from the U.S. Department of Transportation found that deer-vehicle crashes cost more than $8 billion annually in damages. 

Safer roads aren’t the only benefit of species reintroduction. The reintroduction of wolves in Yellowstone in 1995 has had monumental effects on the local ecosystem. With wolves to hunt elk, birch trees have been able to grow back, supporting beavers which in turn build dams to ameliorate the health of streams and rivers. 

Source study: PNAS – Wolves make roadways safer, generating large economic returns to predator conservation