The lost road: do transportation networks imperil wildlife population persistence?

Abstract

The global road network is rapidly growing associated with human economic development. This growth also entails a high toll for biodiversity, with several well-documented negative impacts on different species. However, there is still a great lack of knowledge about the effects of roads on the persistence of wildlife populations. Here, we aimed to summarize our current knowledge on this topic, based on systematic reviews. We found that only a small proportion of studies (8%) focused on the effects of roads on population persistence. Most of these studies were about large mammals and were performed in high-income countries. Furthermore, these works studied only 2% of those species identified by the IUCN Red List as threatened by roads. Overall, our results show that we are far from understanding how roads affect the long-term viability of wildlife populations inhabiting road-effect zones. Addressing this challenge will require modifying our conceptual perspective, from short-term to long-term studies, from single road sections to focusing the landscape scale, and strive to obtain empirical data to support sound analyses to assess how road impacts affect the survival of wildlife populations, namely with information required to perform approaches such as population viability analyses. We highlight some key studies from our reviews that have addressed this global conservation concern with population-oriented approaches.