Comparison between wildlife-vehicle collisions and fauna recorded by camera traps in highways and fragments of Mixed Ombrophilous Forest in Southern Brazil

Road expansion and the consequent fragmentation of natural habitats pose significant challenges to biodiversity, particularly in endangered biomes such as the Atlantic Forest. This research aimed to inventory the vertebrate species hit along two highways and evaluate the diversity of vertebrate fauna in adjacent forest fragments, recorded by camera traps. It also sought to identify seasonal patterns of wildlife-vehicle collisions and analyze risk factors associated with fauna mortality. The study was conducted on the VRS 873 and ERS 373 highways in the municipalities of Morro Reuter, Santa Maria do Herval, and Gramado, within the Rio Caí Hydrographic Basin, in the state of Rio Grande do Sul, Brazil, between September 2023 and August 2024. Complementary methodologies for monitoring fauna were used, including systematic surveys of carcasses on the roads and records of nine camera traps, installed in adjacent fragments of Mixed Ombrophilous Forest. Photographic records and wildlife-vehicle collisions totaled 58 vertebrate species, belonging to four taxonomic classes, distributed in 19 orders and 41 families. Amphibians were the group most impacted by wildlife-vehicle collisions, followed by reptiles and mammals, while birds had the lowest incidence. Seasonality influenced the frequency of collisions, possibly associated with climate variations and reproductive patterns of the species. The comparison between data from the highways and forest fragments revealed significant differences in the composition of the recorded fauna, indicating that some groups—particularly amphibians and reptiles—are more vulnerable to wildlife-vehicle collisions due to factors such as displacement behavior and habitat availability. The identification of wildlife-vehicle collisions hotspots highlights the need for mitigating strategies, such as wildlife passages and road signs, to reduce the impacts on biodiversity and subsidize conservation policies in the region.