Wildlife Crossing Structures and Road Mortality Reduction

Roads are one of the leading causes of wildlife mortality globally, but wildlife crossing structures — underpasses, overpasses, and culverts — have proven highly effective at reducing collision mortality and reconnecting fragmented habitat.

Key Facts

Vehicles kill an estimated one million vertebrates per day in the United States alone
Wildlife crossings have reduced wildlife-vehicle collisions by 70-95% in monitored locations when combined with appropriate fencing
The Banff wildlife overpass system in Canada has been used by cougars, wolves, grizzly bears, and elk within years of installation
Smaller culvert underpasses are effective for amphibians, badgers, otters, and small mammals at a fraction of overpass cost
New road and highway projects are increasingly required to incorporate wildlife crossing assessments by environmental regulations

Welfare Considerations

Road mortality causes acute welfare harm to individual animals — death, injury, and orphaning of dependent young — while fragmenting populations and reducing genetic diversity. Wildlife crossings address both welfare and conservation simultaneously. The cost-benefit case for crossings is strong: reduced vehicle damage and human injury costs frequently exceed crossing construction costs in high-mortality road sections. Citizen science monitoring of road kill hotspots provides the data needed to prioritise crossing investment.

What You Can Do

Report wildlife road kill through citizen science platforms such as Project Splatter or iNaturalist to build evidence for crossing investment
Advocate for wildlife crossing assessments to be mandatory in all new road development planning
Support organisations campaigning for crossing retrofits on high-mortality existing road sections
Reduce driving speed in known wildlife movement areas, particularly at dawn and dusk