Wildlife-vehicle collisions simplify regional food webs

Roads and traffic stand as major threats to biodiversity, primarily due to roadkill, affecting the functioning of ecosystems and the provision of ecosystem services. Understanding how wildlife-vehicle collisions affects the dynamics of ecological interactions is essential to help manage human impacts on biodiversity, but such studies remain largely unexplored. We investigated the intricate relationship between roads, species vulnerability to roadkill, and the ensuing effects on food webs across Europe. Utilizing road density thresholds and trophic interaction data, we constructed regional food webs to assess the potential loss of trophic interactions due to roadkill. Our analysis, encompassing 551 species across three trophic levels, revealed spatially varied impacts, with areas surrounding major cities facing drastic trophic interaction losses exceeding 90%. Notably, 186 species faced significant risks of local extinction due to direct roadkill effects, while a similar number (190 species) encountered trophic interaction losses due to indirect effects (loss of prey or predator). Apex predators exhibited lower direct roadkill impacts while basal-level species are more exposed to direct effects, potentially triggering a cascade of interaction disruptions. Our findings underscore the necessity for tailored conservation measures to reduce roadkill risk, targeting different trophic levels, to preserve ecological network integrity amidst road development programs.