The Impact of Roads on Birds

Abstract

Most published studies regarding the impact of roads on birds focus either on collision with vehicles or noise pollution and disturbance effects, but also habitat fragmentation and chemical pollution. Fewer studies describe positive influences of roads on birds. Many studies originate from Europe and North America. Recently, contributions from South America have increased, but studies from Asia, Australia and Africa are still scarce. This pattern is consistent across collision and disturbance topics, except barrier effects, for which most contributions come from South America, especially from rainforests. Studies concerning collision with vehicles generally focus on all road-killed vertebrates while others specifically focus on mortality across all bird taxa. For most other impacts, passerines are the most investigated taxonomic group, although there are also relevant contributions focusing on birds of prey, owls, and some regionally endangered species. Roads can also provide some benefits to some birds, providing new foraging opportunities in the form of carcasses of road-killed animals, garbage or spills from passing vehicles. However, there are negative consequences of this proximity, and roads might be an ecological trap for some species. Although roads have many negative effects on bird populations, road mortality, fragmentation and traffic noise can be more detrimental than other types of impacts. The impacts of roads on birds are very variable across landscape context, communities, taxa, or road type. Thus, it is crucial to investigate the situations where a road will or will not have negative effects for birds. Given the recent expansion of transportation infrastructure in many developing countries, it is also urgent to address long-term population consequences of road impacts for birds, in particular those with specialised habits.