Eastern Box Turtle (Terrapene carolina carolina) Shell Damage and Health in an Urban Landscape

Abstract

Eastern box turtles (Terrapene carolina) are becoming increasingly threatened by the rate of urbanization and habitat fragmentation. The high population density and heavy urbanization of Long Island, New York, provide an ideal system to examine possible drivers of differences in eastern box turtle shell damage and health in an urban landscape, as well as possible differences in sex and stage ratios. Over the course of our 2-yr study, we captured a total of 189 unique individual eastern box turtles across 20 sites on Long Island. Shell damage was evaluated according to a 5-level ranking system based on the amount and type of damage an individual turtle exhibited. To study eastern box turtle health, we calculated a body condition index using each turtle’s body weight and straight-line carapace width. All damage and health data were compared by site, sex, and life stage using generalized linear models. These relationships were also analyzed against a set of land cover and land use variables. Across all comparative analyses performed, only the US Geological Survey land cover variable Dryland Cropland and Pasture showed a significant relationship to shell damage. Additionally, Long Island’s eastern box turtles appear to exhibit greater rates of shell damage when compared with turtles in more rural parts of their range. We found male-biased sex ratios across the island; however, no definitive driver was identified. Our study underscores the need for future work on the long-term viability of eastern box turtle populations, specifically those inhabiting areas of high human population density.