Identifying and mitigating the impacts on primates of transportation and service corridors

Most primate populations are declining, with 60% of species facing extinction. The expansion of transportation and servicecorridors (T&S),i.e. roads, rail, and utility and servicelines, poses a significant yet underappreciated threat. With the development of T&S corridors predicted to increase across primates' ranges, it is necessary to understand the current extent of its impactson primates, the available options to mitigate these effectively,andrecognize research and knowledge gaps. By employing a systematic search approach to identify literature that described the relationship between primates and T&S corridors, weextracted information from 327 studies published between 1980 to 2020. Our results revealed that 218 species and subspecies across 62 genera are affected, significantly more than the 92 listed by the IUCN Red List of Threatened Species. The majority of studies took place in Asia (45%), followed by mainland Africa (31%), the Neotropics (22%), and Madagascar (2%). Brazil, Indonesia, Equatorial Guinea, Vietnam, and Madagascar contained the greatest number of affected primate species. Asia featured the highest number of species affected by roads, electrical transmission lines, and pipelines and the only studies addressing the impact of rail and aerial tramways on primates. The impact of seismic lines only emerged in literature from Africa and the Neotropics. Impacts are diverse and multifaceted, e.g. animal-vehicle collisions, electrocutions, habitat loss and fragmentation, impeded movement and genetic exchange, behavioural changes, exposure to pollution, and mortality associated with hunting. Although several mitigation measures were recommended, only 41% of studies focused on their implementation, whilst only 29% evaluated their effectiveness. Finally, there was a clear bias in the species and regions benefiting from research on this topic. We recommend that government and conservation bodies recognise T&S corridors as a serious and mounting threat to primates and that further research in this area is encouraged.