Seasonal Activity and Species Habitat Guilds Influence Road-Kill Patterns of Neotropical Snakes

Abstract

Animal road mortality is the product of multiple factors. We sought to examine the impact of roads on Bolivian biodiversity by quantifying road mortality in a community of tropical snakes and examine variation in road-kills in the context of extrinsic (seasonal effects) and intrinsic factors (habitat guild, sex). From 2007 to 2011, we surveyed the old Santa Cruz-Cochabamba highway and local dirt roads in Florida Province, Santa Cruz Department, Bolivia. We observed 1,444 snake road-kills comprised at least 32 species from 21 genera and 4 families. Nearly one fifth (18.4%) of road-killed species are endemic to the region. A temporal peak in road mortality was observed in February in the middle of the rainy season and was lowest in July coinciding with the dry season. Male snakes were more frequently killed than females and male mortality peaked during the mid to late rainy season. Habitat guild had a significant influence on the species occurrence during the road surveys; road-kills of terrestrial snakes were observed more frequently compared with fossorial, arboreal, semi-arboreal, and semi-aquatic species. The impact of roads on Bolivian biodiversity, including snakes, is expected to increase, as road networks in the region continue to expand. Documenting additional interspecific and intraspecific variation in vulnerabilities to road mortality is needed to better understand the long-term impacts of roads on population persistence as well as inform the design and implementation of mitigation efforts.