Influence of ecology and landscape on snake road mortality in a sagebrush-steppe ecosystem

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Roads fragment our landscape, posing a severe threat to the persistence of wildlife populations through losses of individuals to direct mortality and decreased connectivity of habitat. Although snakes possess a particular suite of life history characteristics that make them especially vulnerable, they tend to be underrepresented in research examining vertebrate road mortality. Here, the authors report a statistical analysis of snake mortality along a 183-km road circuit in sagebrush-steppe habitat located in southeastern Idaho. They describe differential road mortality across snake species, season, sex, and age. They also analyze both fine-scale and broad-scale habitat measurements to identify various habitat and landscape factors associated with road mortality for snakes. Results show clearly that snake road mortality is influenced by interactions among demographic, ecological, and temporal factors. Vagile species and life stages were particularly vulnerable to road mortality during periods of peak activity. Gophersnakes dominated the road observations, with adult male mortality peaking in spring and high casualties of neonates in the fall. Snake crossings were especially common along roadsides with high vegetative cover, in areas dominated by nonnative grasses. These results suggest the potential for snake populations to become fragmented over time and that habitat conversion and species invasions may be compounding this effect. This study suggests that conservation efforts need to account for inter- and intraspecific differences in road mortality risk and provides guidance for roadside management that may serve to minimize vertebrate mortality on roads.

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ELECTRONIC FILE - Zoology