The distribution of vertebrate roadkill varies by season, surrounding environment and animal class

Due to rapid human expansion in the last century, wildlife roadkill is becoming a concerning threat to biodiversity and human safety. The frequency of roadkill events depends on factors related to specific traits of the road –fencing, tortuosity, or type of habitat, among others– and the animal ecology –such as activity patterns, reproductive season, thermoregulation– which, in turn, are related to environmental factors (with seasonal variations). Here we assessed roadkill mortality of terrestrial vertebrates over the year. To do this, we sampled 10 road sections (of 3 km, by walk) in the south of Spain for a full year, registering the carcasses of run-over vertebrates. Then, we analysed the spatiotemporal patterns of roadkill events for the four vertebrates’ classes and the effects of road traits (presence of fence, tortuosity, distance to water body) and environmental variables (mean temperature and precipitation). Mammals suffered the highest mortality by roadkill (45.72%). Tortuosity of the road section and precipitation were not related to the number of collisions, while the presence of fences was related to an increase in roadkill events, and mean temperature significantly increased the probability of collision of mammals, birds, and reptiles. There was a seasonal effect in the number of collisions, which spatial pattern depended on the class of vertebrates. All this leads us to conclude that, to reduce the impact caused by roadkill mortality on the wildlife we need specific measures to be taken in each critical place for each vertebrate group.