Ecology and genetics of Blanding's turtles in an urban landscape

The Blanding's turtle (Emydoidea blandingii) inhabits shallow freshwater habitats in North America and is undergoing population declines throughout its range. The loss of habitat is largely responsible for the demise of this semi-aquatic turtle. Moreover, the subdivision and insularization of remaining habitats through urban development are expected to become major threats to the species' persistence. Most knowledge to date has been generated in areas where habitats are relatively undisturbed by urban development. Consequently, the potential effects of urbanization on Blanding's turtles are not well established. To develop a better understanding of how Blanding's turtles respond to urban development, I initiated an investigation of the ecology and genetics of Blanding's turtles in the intensely developed Greater Chicago metropolitan area (GCMA) in northeastern Illinois. My findings indicated that populations in the GCMA are small and isolated and have juvenile recruitment problems, though do not appear to be suffering genetically. As expected, Blanding's turtles relied extensively on wetlands, but during dry periods turtles were often found on land and in permanent residential ponds located on private property adjacent to preserve boundaries. Based on these findings, primary efforts toward the conservation of Blanding's turtles in the GCMA should aim to increase population sizes and provide permanent wetlands within preserve boundaries and protect those used by turtles on private property. Because adult survival was high in the populations studied, low juvenile recruitment appears to be the major factor resulting in small population sizes. Thus, management interventions need to focus on increasing juvenile recruitment rates to increase the size of Blanding's turtle populations in the GCMA. Potential strategies to increase juvenile recruitment include "headstarting" or the captive propagation of young turtles that are subsequently released back into the wild and the protection of nesting areas of Blanding's turtles from predators and human disturbances. Ultimately, however, the fate of Blanding's turtles in the GCMA will depend upon the protection and proper management of habitat for Blanding's turtles at all life-stages. Thus, conservation strategies that combine a holistic approach to habitat management with those that increase juvenile recruitment will be the most successful.