Patterns of Snake Road Mortality on an Isolated Barrier Island

Abstract

<p>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 (<i>Coluber constrictor, Opheodrys aestivus, Pantherophis alleghaniensis, Cemophora coccinea</i>, and <i>Nerodia fasciata</i>) killed on roads on Bald Head Island, an isolated barrier island with traffic consisting primarily of slow-moving electric golf carts. <i>Coluber constrictor</i> 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 (<i>C. constrictor, C. coccinea,</i> and <i>N. fasciata</i>). 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. </p>