Annika Hellerud

Traffic Volumes Impact Sex Ratios of Painted Turtle Populations in Ramsey County

Road mortality is currently one of the biggest threats to freshwater turtle populations. Female turtles cross roads more frequently than male turtles in order to nest, and this means females are more prone to road mortality. The Twin Cities is a particularly interesting place to study road-induced turtle mortality because it has a diverse landscape with a variety of traffic volumes, road densities, and wetland areas. Our goal was to determine the extent to which the sex ratio of Ramsey County painted turtle populations can be explained by the traffic volume of nearby roads. We also asked if these relationships differed with age and distance from habitat to the nearest road. We placed hoop traps in six wetlands, and sampled turtle populations from mid-May through early August. The sample size was small (19) but suggested a pattern. Wetlands near higher traffic volume roads were more likely to have a male-biased sex ratio. Female turtles were found across a greater range of wetlands near roads with greater traffic volumes and across a greater range of distance to nearby habitats. Additionally, sex-ratios varied greatly between different ages, with most adults captured being female and most juveniles being male. None of these results was statistically significant, however. Future work should continue to investigate the relationship between sex ratios and traffic volume, as well as the sex ratios within age structures of populations. Further, future research should have multiple trapping seasons in order to obtain an adequate sample size.