Road verges are probably the larger and more widespread infrastructure related habitat. In an era where companies are highly encouraged to offset the environmental impacts of their activity, it is tempting to use them for conservation purposes, promoting their role as corridors or biodiversity refuges. For instance, verges are considered the backbone the European Green Infrastructure due to their potential role in linking major habitat patches. However, endorsing conservation duties for road verges may be dangerous for mobile fauna because roadkill risk is increased and regular vegetation cutting associated with verge paring destroys habitats and kills directly less mobile organisms. Here we present the results of four studies aiming to evaluate the ecological importance of road verges for fauna. These were done in the framework of the projects MOVE, LIFE LINES and POPCONNECT, in typical Mediterranean area in southern Portugal. We have accessed the role of verges as refuges and corridor for small mammals, feeding areas for bats and ecological traps for small mammal predators. (1) Using acoustic surveys in 1000m transects perpendicular to roads we found that bat activity peaks on verges of roads crossing open agricultural landscapes, suggesting that in these circumstances they may be an important last remnant feeding habitat for bats. (2) In a small mammal trapping study conducted in highly grazed areas we evaluated the importance of road verges as refuge for small mammals and compared it with the importance of riparian vegetation strips. Abundance of mice is about 4.6-fold higher on verges than in the immediate surrounding open fields and is similar to abundance recorded on riparian strips. Thus, in landscapes modified by humans and with reduced ground vegetation cover, verges are important refuges and constitute equally vital habitats for small mammals as do riparian vegetation strips. (3) Using capture-recapture methodologies and graph-theory-based connectivity metrics (derived from the probability of connectivity index) we found, for the wood mouse, that nodes located on verges and links rooted on them contributed significantly more to the overall landscape connectivity than nodes and links located elsewhere, despite the study have been conducted in a well preserved Mediterranean forest area. This shows the high importance of verges as small mammal corridors, even within well preserved landscapes. (4) In another study we have related the location of roadkills of large snakes, owls and mammal carnivores with the abundance small mammals and wild rabbits on verges, using redundancy analysis. Abundance of prey on verges explained 8 to 33% of variation in predator roadkills depending on the species. Moreover, we have found a strong positive association between road casualties of species belong to all types of predators and the abundance of wood mice and rabbits, the two main prey in studied area, on verges. Results support the hypothesis that prey abundance on road verges may be a major driver explaining predator roadkills.
Based on the results of the above studies criteria for where to promote verges for conservation purposes and implications for verge management will be discussed.