29th Annual Meeting and Symposium of the
Desert Tortoise Council, February 20-23, 2004
Abstracts

The Effects of Roads on Snakes

Charles R. Peterson and Denim Jochimsen
Department of Biological Sciences, Idaho State University, Pocatello, ID 83209-8007

In this presentation, we summarize information on the direct and indirect effects of roads on snakes and some of the actions that can be taken to mitigate these effects. The basis for this presentation is a review of approximately 30 papers from the peer-reviewed and gray literature. Several snake characteristics may contribute to their susceptibility to road mortality, including their relatively long seasonal movements between required habitats (e.g., overwintering and foraging areas), behavioral thermoregulation utilizing road surfaces, elongate body shape, and negative perception by motorists. Species that are more vagile are generally more likely to suffer from road mortality. Direct effects of roads include the killing of snakes by vehicles and road construction activities. One study documented 13,000 road-killed snakes, and several other studies have documented hundreds of snakes killed on roads. Some studies also indicate that road mortality is having negative population level effects. Blasting involved with road construction is known to have affected communally overwintering snakes. Indirect effects of roads may include influencing snake movements, habitat fragmentation and alteration (e.g., changes in temperature, moisture, light, noise, and pollutants), changes in prey and predators, and increased access for collectors. Mitigation activities include changing the placement of roads during planning, warning signs, seasonal road closures, and the construction of road-crossing structures (fences, tunnels, bridges, etc.). The correct placement of such mitigation efforts is critical to their effectiveness.