Survival and recruitment of semi-aquatic turtles in an urbanized region

Turtles are long-lived organisms that require high survivorship to maintain stable populations. Additionally, turtles are thought to be particularly susceptible to negative effects associated with anthropogenic habitat modification such as increased presence of human-subsidized predators and increased road mortality. Recruitment may also be reduced in populations surrounded by developed landscapes because of high road densities which limits connectivity among habitats or because of limited nesting sites. To address the impacts of habitat development on turtle vital rates, we studied three species of semi-aquatic turtles, yellowbelly sliders (Trachemys scripta), eastern mud turtles (Kinosternon subrubrum), and common snapping turtles (Chelydra serpentina), in the urbanized Charlotte-metropolitan area of North Carolina. Mark-recapture data were analyzed in Program MARK using AIC model selection methods to evaluate models analyzing the effects of pond, sex, and time on both survivorship and recruitment rates. Our results yielded high survivorship estimates for sliders and snapping turtles (73-92. 5% and 91. 4-99. 4%, respectively), indicating that these species were likely not severely affected by habitat modification. In contrast, mud turtles exhibited lower survivorship estimates (56. 8-73. 6%) than have been previously documented for this species, an observation we attribute to their reliance on terrestrial habitats where they may encounter greater densities of mesopredators in developed areas. Recruitment estimates indicated that most populations were subsidized by sizable additions each year, with the notable exception of snapping turtles whose movement may be limited by increased road densities. Our results suggest that anthropogenic habitat modification has species-specific effects and could imperil certain populations in urbanized areas. © 2010 Springer Science+Business Media, LLC.