Biological characteristics influence mammal road kill in an Atlantic Forest-Cerrado interface in south-western Brazil

Few studies have addressed mortality causes of neotropical mammals on roads, especially considering the extensive road system and biodiversity. The goal of this article was to examine the biological factors related to mortality of non-volant mammals on roads of an Atlantic Forest-Cerrado interface in Brazil. Mammals were recorded during a seven-year period and over 3900 km of roads, in order to estimate data for abundance of species in habitats (areas) and frequencies of species killed by cars on roads. Areas (n=80) within two adjacent ecoregions (Atlantic Forest, n=23; Cerrado, n=57) were searched for records of mammals. Thirty-two species were surveyed, comprising 480 dead mammals on the roads and 503 records of the presence of species in adjacent habitats. Ten species that have been recorded in these habitats were never found dead on the roads, which could indicate road avoidance behaviour. Correlations and multiple regressions showed that abundance is the more important variable influencing road kill, followed by habit (nocturnal/diurnal) and threat category. Therefore, large-sized and threatened species tended not to be run over, as well as agile, mostly diurnal, or recent, advanced species (carnivorous or herbivorous). The data are discussed in the light of Road Impact Index (RII), with five species exhibiting high RII (Cerdocyon thous, Dasypus novemcinctus, Euphractus sexcinctus, Myrmecophaga tridactyla and Tamandua tetradactyla) being run over more than expected bases on their abundance, and dozens of species exhibiting lower RII, belonging to those avoiding or being isolated by roads.