Patterns of road mortality in Vipera latastei and V. seoanei from northern Portugal

摘要: The ecological effects of roads and traffic on wild animal and plant species are vast and complex (Spellerberg, 1998), as they usually increase mortality during and after road construction, change animal behaviour, fragment habitats and create barriers, change the chemical environment, enhance the spread of exotic species and increase the human use of the landscape (Trombulack and Frissel, 2000). Particularly, road killing is one of the most important sources of unnatural mortality in wildlife species, affecting from invertebrates (Seibert and Conover, 1991) to large mammals (Groot Bruinderink and Hazebroek, 1996), including ground, air-dwelling and aquatic species (Dodd et al., 1989; Mumme et al., 2000; Carr and Fahrig, 2001). Road mortality modifies the demography and population structure of species, and in certain circumstances, it can be the primary source of mortality