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Reintroduction of Apex Predators to Reduce Wildlife-Vehicle Collisions

Started: February, 2023 End Date: September, 2023 Project ID #4WA237 Status: Ongoing


Reductions in wildlife-vehicle collisions (WVCs) have been witnessed in studies where ungulate herds were reduced by culling, or killing, to reduce population size. The presence of apex predators can also affect the density, behavior, and physiology of an ungulate population. This research seeks to provide additional support that the presence of an apex predator in a landscape has the ability to reduce WVCs along a section of road. Carcass data collected by the National Park Service in Yellowstone National Park along US-191 between 1989-2021 will be used to compare WVCs before and after wolves were introduced in 1995.

Benefits: Reducing WVC improves human safety and the safety and population longevity of animals along roadways.


This project uses a historic data set from Yellowstone National Park to conduct a before-after study related to the reintroduction of wolves in the area. Wolves were reintroduced to the park in the mid-90s, and a pack was established near US-191 around 2002. By controlling for traffic volumes along the road, we will be able to determine how the presence of wolves in the area affect the rate or wildlife-vehicle collisions.


Sponsors & Partners

  • Federal Highway Administration (FHWA) Sponsor

Part of: Road Ecology, WTI-SURTCOM, Small Urban, Rural and Tribal Center on Mobility (SURTCOM)

Project Tagged In: wildlife vehicle collisions, road safety, Predator reintroduction

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