Beware that the lack of wildlife mortality records can mask a serious impact of linear infrastructures

Abstract

Linear infrastructures (e.g. roads, railways or power lines) promote a myriad of negative impacts on wildlife around the world, of which direct mortality is the most visible one. When high mortality rates are found, mitigation measures are often discussed and applied. On the other hand, the lack of mortality is commonly interpreted as evidence of low impact on wildlife. We argue that the lack of mortality may actually mask two pervasive effects of linear infrastructures on animal populations: past massive mortality, causing local extinctions, or strong barrier effects due to the inability or reluctance of individuals to traverse the infrastructure corridor. In order to obtain a sound impact assessment of the linear infrastructures on wildlife, research is needed that integrates long-term mortality data with information on the abundance of the focal species, their genetic patterns and movement behavior. We discuss the implications of these impacts for both infrastructures and landscape management.