Railway ecology vs. road ecology: similarities and differences

Abstract

Railway ecology is an emerging discipline. In this review, we focus on what is known today regarding the impacts of railways on wildlife, and on the methods to identify, monitor, and mitigate these impacts. Wildlife-train collisions are the most often reported impact, although railway lines can also represent barriers to animal movement, bisecting populations or reducing wildlife access to resources. Little is known on the impact of habitat loss and fragmentation due to railways alone, or on their disturbance effects, including pollution (noise, chemical, light), and on the potential to provide habitat connectivity or surrogate habitats for native species in degraded landscapes. Molecular techniques are one of the most promising methods to study the impacts of railways, as genetic analyses are useful to identify both population sub-structuring, and to assess the potential restoration of functional connectivity by mitigation measures like wildlife passes, or to estimate effective population sizes. Field work is necessary to provide credible mortality rates, which, combined with computer simulations, can allow for estimations of the impact of mortality on population viability. Studies should ideally have Before-After-Control-Impact designs and be long-term. We need to improve mortality estimates, and to understand how impacts threaten population dynamics. We need to go from local-scale studies (e.g., animals use the underpasses) to landscape-scale (i.e., where to place these underpasses to maximize the connectivity at regional/populational levels). Finally, we need to expand our knowledge on less studied, less charismatic species, and to explore the potential environmental benefits of green practices on railway corridors.