Mountain Lions Cut Deer-Car Crashes by 76% in Washington

Living near mountain lions might sound terrifying, but new research shows these big cats are actually saving human lives on the road.

Scientists studying Washington State's Olympic Peninsula discovered that areas with healthy cougar populations saw 76 percent fewer collisions between deer and vehicles. In the U.S., deer cause over 1.5 million car crashes every year, killing more than 200 people and injuring tens of thousands more.

Researchers tracked 59 GPS-collared pumas and analyzed footage from 503 camera traps between 2020 and 2025. They also mapped where more than 950 deer and elk collisions happened across the peninsula, which resulted in two deaths and over 80 injuries during that five-year period.

The findings surprised even the scientists. Pumas weren't reducing crashes by eating more deer and lowering their population. Instead, the mountain lions were changing how deer behaved simply by existing nearby.

Fear of becoming a puma's dinner pushed deer 15 percent farther away from roads and into more remote areas with denser vegetation. The predators also forced deer to become more active during daylight hours, when drivers can spot them more easily and hit the brakes in time.

"They're saving lives. They're reducing damage to infrastructure. They're saving millions of dollars," says Mark Elbroch, a mountain lion biologist at Panthera who co-authored the study published in Current Biology.

The Ripple Effect

The discovery adds mountain lions to a growing list of predators that provide unexpected benefits to human communities. Wolves have helped restore ecosystems in Yellowstone, and sharks protect seagrass beds that fight climate change.

Kaitlyn Gaynor, a wildlife ecologist at the University of British Columbia not involved in the research, notes that carnivores can reduce human-wildlife conflicts "through complex ecological pathways" we're only beginning to understand.

The timing matters too. As puma populations naturally expand and conservationists consider reintroducing them to historic habitats, this research offers communities a practical reason to welcome their return.

Elbroch hopes the findings will help people see large predators as neighbors worth protecting rather than threats to eliminate. Coexistence takes work, but the payoff goes beyond dollars saved on insurance claims and hospital bills.

When we make room for mountain lions in our landscapes, they return the favor by making our roads safer for everyone.