The road less traveled: Addressing reproducibility and conservation priorities of wildlife-vehicle collision studies in tropical and subtropical regions

Roads are expanding at an extremely high rate, and have a significant direct impact on biodiversity through wildlife-vehicle collisions (WVC). This threat is well documented for the temperate regions of North America and Europe, but the information from the remaining countries is limited or scattered. To evaluate reproducibility and conservation value of current WVC data, we analyzed 308 peer-reviewed studies from 41 tropical and subtropical countries across 20 years and five languages, representing 2485 vertebrate species and 139,602 unique WVC events. Only 107 of these 2485 species have roads listed as a threat within the Threat Classification Scheme developed for the IUCN Red List. Study design mostly focused on mammals, and specifically on medium- to large-sized species. We also revealed a strong geographic bias towards South America, and primarily Brazil, while both Asia and Africa require more long-term standardized road mortality studies. Overall, we identified several reporting gaps in WVC studies that limit reproducibility and comparability. Our results highlight the need for standardized reporting within wildlife-vehicle collision studies, and the need for further research on a number of threatened species with potentially high road mortality rates.