Roads are among the most pervasive and damaging human infrastructure for wildlife welfare. The global road network exceeds 65 million kilometers, and road-related mortality kills an estimated 1-2 million large vertebrates daily in the US alone — plus billions of smaller animals. Road ecology science is developing increasingly effective interventions.
The welfare impact of vehicle strikes is often underestimated. Animals struck by vehicles experience:
Wildlife crossing structures — overpasses, underpasses, culverts, and amphibian tunnels — are among the most evidence-based wildlife welfare interventions available. Banff National Park's 44 crossing structures have reduced large mammal road mortality by 80-96%. Florida's wildlife underpasses reduced Florida panther road mortality from 5-8/year to near zero on mitigation corridors. Each crossing structure prevents dozens to hundreds of individual welfare events annually over its lifespan.
Amphibian road mortality during seasonal migrations is one of the most significant but invisible wildlife welfare events. Common toads in Europe, spotted salamanders in North America, and various frog species migrate en masse to breeding ponds, crossing roads with enormous mortality. "Toad tunnels" and road closures during migration nights are welfare interventions implemented in hundreds of European municipalities. Volunteer bucket brigades carry amphibians across roads in countries where infrastructure doesn't exist.
Best-practice road design incorporating wildlife welfare: wildlife detection systems with driver warning lights; reduced speed zones near known crossing areas; barrier fencing to direct animals to crossings; wildlife-friendly drainage culverts (avoiding drowning traps); vegetation management maintaining sight lines; and noise barrier designs that reduce chronic stress for animals near highways.