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

STUDENT POSTER

Road Mortality of Snakes on the Eastern Snakes River Plain

Denim M. Jochimsen
Dept. of Biological Sciences, Idaho State University, Pocatello, ID 83209-8007

This research documents the magnitude of road mortality of snakes, provides insight into how this mortality differentially impacts individuals, and examines the seasonal patterns by sex and age class. I conducted the study by road cruising a 160-km road loop in the eastern Snake River Plain of Idaho from May through October of 2003. I observed a total of 259 snakes on roads along the survey route and across the entire survey period; ninety percent of these animals were found dead on the road surface. I recorded the road mortality of 4 species of snakes belonging to families Colubridae and Viperidae. However, the majority of observations belonged to 2 species with Gopher Snakes (Pituophis catenifer) comprising 74% of all road records, and Western Rattlesnakes (Crotalus viridis) comprising 18% of all road records. Overall, I observed adult males more often than any other age or sex class. Road mortality varied seasonally across age and sex classes, and between species. The average number of snakes observed per day while road-cruising was highest during the month of September, although this result is not statistically significant due to the high variance in the numbers observed per day across months. Spatial analysis of the data indicates that the observations are clustered across the survey route. Future analyses will focus on identifying which landscape factors affect the spatial pattern of road mortality. Such analyses may help with efficient placement of mitigation efforts.