Roads, while central to the function of human society, create barriers to animal movement through collisions and habitat fragmentation. Barriers to animal movement affect the evolution and trajectory of populations. Investigators have attempted to use traffic volume, the number of vehicles passing a point on a road segment, to predict effects to wildlife populations approximately linearly and along taxonomic lines; however, taxonomic groupings cannot provide sound predictions because closely related species often respond differently. We assess the role of wildlife behavioral responses to traffic volume as a tool to predict barrier effects from vehicle‐caused mortality and avoidance, to provide an early warning system that recognizes traffic volume as a trigger for mitigation, and to better interpret roadkill data. We propose four categories of behavioral response based on the perceived danger to traffic: Nonresponders, Pausers, Speeders, and Avoiders. Nonresponders attempt to cross highways regardless of traffic volume. Pausers stop in the face of danger so have a low probability of successful crossing when traffic volume increases. Hence, highway barrier effects are primarily due to mortality for Nonresponders and Pausers at high traffic volumes. Speeders run away from danger but are unable to do so successfully as traffic volume increases. At moderate to high volume, Speeders are repelled by traffic danger. Avoiders face lower mortality than other categories because they begin to avoid traffic at relatively low traffic volumes. Hence, avoidance causes barrier effects more than mortality for Speeders and Avoiders even at relatively moderate traffic volumes. By considering a species’ risk‐avoidance response to traffic, managers can make more appropriate and timely decisions to mitigate effects before populations decline or become locally extinct.
Roads and traffic are typically more of a threat to the conservation of birds rather than a safety issue for motorists. Some bird species have biological features and life history traits that make them particularly vul nerable to habitat loss from roads and mortality due to wildlife-vehicle collisions (WVC). Road planning that proactively considers the biological needs of birds will help avoid project delays and extra costs for mitiga tion, as well as achieve positive outcomes for birds. Several strategies effectively avoid or mitigate the negative effects of roads on birds. 33.1 Roads can adversely affect birds despite the common assumption that birds avoid mortality and barrier effects because they can fly. 33.2 Wildlife-vehicle collisions kill millions of birds annually. 33.3 Planning the timing and location of road construction and maintenance is crucial for the survival and conservation of birds. 33.4 Flight diverters may reduce the likelihood of vehicle collisions with birds. 33.5 Wildlife crossing structures can decrease the barrier effect. 33.6 Structural changes along roads can reduce noise impacts. 33.7 Roadsides should be managed to make them less attractive to birds.Implementing design features that separate birds from traffic, reducing resources that attract birds to the roadway and minimising disruptive light and noise emanating from the roadway are the main mitiga tion measures for birds. However, more research is needed to quantify the various effects of roads and the cumulative effect of road networks on birds and, perhaps more critically, to explore ways to prioritise and effectively mitigate the most negative impacts.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.