Mountain Lions Linked to Fewer Deer-Vehicle Collisions on Olympic Peninsula

A study published in Current Biology examined the relationship between mountain lion activity and deer-vehicle collisions on the Olympic Peninsula in Washington state. Researchers combined traffic accident data with images from camera traps to map where mountain lions, also known as cougars or pumas, were present.

The analysis found that deer were 15 percent less likely to be found near roads in areas where mountain lions were active. Since mountain lions prey primarily on deer, the prey species appears to avoid open spaces such as roadways when predators are nearby.

This behavioral shift corresponded with a 67 percent drop in the odds of a traffic accident involving deer in those same areas. The researchers say this is the first demonstration of such an effect in a region where large predators are well established.

Coauthor Mark Elbroch of Panthera, a wild cat conservation organization, noted that public discussion of mountain lions often centers on the risks they pose to people or livestock. He said the findings highlight an overlooked benefit of having the predators on the landscape.

The study does not quantify the total number of collisions prevented or assess economic impacts. It also does not examine whether the reduction in collisions holds across different seasons, road types, or traffic volumes.

Previous research has suggested predators could reduce wildlife-vehicle collisions, but those studies often focused on areas where predators were recolonizing or present at low densities. The Olympic Peninsula offered a setting with a stable, established mountain lion population.

The authors caution that the results reflect correlation between predator presence, deer behavior, and collision rates, and that other environmental factors could also influence deer movement near roads.

Panthera supported the research as part of its broader work on wild cat conservation. The study adds to a growing body of evidence on the ecological roles of apex predators in human-dominated landscapes.