Abstract

Roads impact wildlife by fragmenting habitats, impeding movement, and though wildlife-vehicle collisions (WVCs). Proven mitigation strategies include wildlife crossing structures, but wildlife also utilize existing water culverts and underpasses to cross roadways. They offer opportunities for retrofitting when budget constraints limit the feasibility of wildlife passages. This study investigates the spatial relationship between roadkill distribution and culvert presence along a four-lane divided freeway (A10) and a two-lane regional highway (R112) in Québec, Canada. I evaluate how culvert structural characteristics (e.g., materials, shapes, functions, and dimensions) and surrounding environmental features influence roadkill frequencies separately for amphibians, mammals, and reptiles. I address three research questions: (1) Does the presence of culverts influence the spatial distribution of roadkill? (2) Which structural and environmental attributes are associated with higher or lower roadkill frequencies for different animal groups? (3) What are the similarities and differences between R112 and A10? The findings provide strong evidence for culvert influence on roadkill patterns. Mammal and reptile fatalities were more frequently associated with dry passages, amphibians with wet passages, and all groups showed a preference for using concrete structures over metal or plastic and for larger culvert openings. The results support the installation of wildlife exclusion fencing to reduce roadkill and improve driver safety. Moving forward, this study may serve as the first phase of a Before-After-Control-Impact (BACI) study, the second phase should evaluate the effectiveness of retrofitted culverts with added wildlife fencing to produce high-inference results for evidence-based WVC mitigation strategies.