Scientists Discovered That Mountain Lions Are Making Roads Safer

Mountain lions are one of nature's most efficient road safety tools, and until now nobody had measured it. A new study in Current Biology paired camera trap data with vehicle collision records across Washington's Olympic Peninsula and found that where puma populations are high, deer-vehicle collisions drop dramatically. Deer cause roughly one to two million wildlife-vehicle collisions in the US every year at a cost running into the billions. Where mountain lions live and hunt, those numbers change. The study found deer were 15% less likely to use road-dense areas when pumas were present, and calculated a 67% lower likelihood of a deer-vehicle collision in high-puma zones. Over five years, the expected number of collisions dropped by 76%. Deer avoid roads because pumas hunt near them, inadvertently moving away from the most dangerous places for both species. They also shifted toward daylight activity in puma territory, meaning the crashes that do still occur are less likely to happen at night, when collisions with large animals are deadliest.

The practical argument for wildlife agencies and transportation planners is hard to ignore. Engineering solutions like fencing and wildlife crossings can cut collisions by 80% or more, but each structure costs millions and covers only a short stretch of road. A puma population, as the study's authors put it, costs nothing to install. Lead researcher Justin Suraci of Conservation Science Partners noted that similar effects likely occur wherever large carnivores still share habitat with deer. "When we talk about pumas, we often focus on the risks they pose," said co-author Mark Elbroch of Panthera. "But we rarely stop to consider the many ways they benefit us as well."

Source:https://www.earth.com/news/pumas-cut-deer-vehicle-collisions/