Patterns of Snake Road Mortality on an Isolated Barrier Island

Road mortality can have severe impacts on wildlife populations. However, the degree of impact is not uniform across all taxa as some possess life-history strategies that render them especially vulnerable to vehicle collisions. As a group, snakes are greatly impacted by road mortality. However, susceptibility to vehicular mortality on roads can vary with species, age, and/or reproductive class. We present data on 186 snakes of five species (Coluber constrictor, Opheodrys aestivus, Pantherophis alleghaniensis, Cemophora coccinea, and Nerodia fasciata) killed on roads on Bald Head Island, an isolated barrier island with traffic consisting primarily of slow-moving electric golf carts. Coluber constrictor was the snake we most frequently found dead on the road. Neonate snakes of all species comprised the majority (59%) of our collected specimens. We observed male-biased sex ratios in collected specimens for three of the species (C. constrictor, C. coccinea, and N. fasciata). Mortality varied significantly across the study period, with the greatest number of kills recorded in early- to mid-August. Mortality was not strongly correlated with the number of visitors on the island. Instead, we suggest that susceptibility to road mortality is likely related to life-history characteristics (including activity patterns). We recommend attempting to reduce mortality of snakes during their peak activity periods with a combination of public education, heightened awareness via snake crossing signs, and reduced speed limits.