A study of habitat selection by Blanding's turtles ( Emydoidea blandingii) in Dutchess County, New York

The Blanding's turtle (Emydoidea blandingii) is a New York State-listed threatened species with several disjunct populations located throughout the state. Blanding's turtles require a variety of habitat types including ponds, wetlands, vernal pools, and the surrounding uplands. Preserving these habitat complexes is necessary to ensure the persistence of Blanding's turtle populations, but this is becoming increasingly challenging in some locations due to significant development pressure. Key components of habitat protection are identifying preferred habitat types and gaining a better understanding of the variables that influence habitat selection. Previous landscape-level studies of turtles have found that land cover type, wetland type, and degree of wetland isolation are important factors related to habitat use.;I investigated the relationship between land cover, wetland type, and wetland isolation on the habitat selection of Blanding's turtles in the Hudson Valley. Radio-tracking data from 39 individual turtles collected over 7 years (January 2002 to December 2008) were examined in a geographic information system (GIS) with readily available sources of land cover and freshwater wetland data. The habitat selection method first described by Neu et al. (1974) was used to identify preference and avoidance of specific land cover types. Correlative approaches, Principal Components Analyses (PCA), and Analyses of Variance (ANOVA) were used to examine the effect of wetland area, wetland type, and degree of wetland isolation on habitat selection.;Both males and females displayed a preference for scrub-shrub land cover and avoidance of both developed and forested land cover. Preference or avoidance of other land cover types varied by sex or season. Wetlands occupied by Blanding's turtles were significantly greater in area than unoccupied wetlands within the study area, but many small wetlands were also utilized. Scrub-shrub wetlands were used significantly more than other wetland types during the winter and were used more than other wetland types during the summer, but not significantly. Forested wetlands were least frequently used. Degree of wetland isolation was not significantly related to the number of turtle encounters. The presence of permanently or semi-permanently flooded deepwater habitat within a 50-m radius of a wetland was positively correlated with turtle encounters.;My findings suggest that this population of Blanding's turtles uses a variety of habitats within its local distribution, with some distinct preferences and avoidances. Scrub-shrub comprises the primary habitat with emergent wetlands, grasslands, and deepwater ponds composing secondary habitat. Developed and forested land cover classes are avoided. Large wetlands tend to be correlated with more encounters, but small wetlands and pools appear to facilitate migration. My results suggest that Blanding's turtles are indeed selecting for specific habitat types and conservation efforts should focus on preserving connectivity between these habitats across the landscape.