Estimating the effects of road mortality on turtle populations

Road mortality is suspected to have contributed to widespread population declines in turtles in the United States, a country with exceptionally high turtle diversity. We examined the issue through a modeling study that integrated road maps and traffic-volume data with simulated movements of (1) small-bodied pond turtles, (2) large-bodied pond turtles, and (3) terrestrial and semiterrestrial ("land") turtles. Our model predicted that road networks typical of the northeastern, southeastern, and central regions have the potential to limit land-turtle populations and, to a lesser extent, populations of large-bodied pond turtles. Nowhere are populations of small-bodied pond turtles likely threatened regionally by road mortality. We conclude that the demographic traits of some turtles, in combination with their mobility, may jeopardize population persistence within road networks typical of the eastern and central United States.