The Influence of Altered Habitat: Landscape Ecology of Freshwater Turtles in Rhode Island

Abstract

Beginning several centuries ago, European settlement brought great change to the landscape of New England. Vast deforestation, subsequent reforestation, and rapid development that continues to this day have had a profound impact on wildlife populations. Elements of this legacy of landscape change have been studied, but the ways in which past and current landscape patterns affect freshwater turtles remains poorly understood. The primary objective of this research was to better understand the influence of the landscape of Rhode Island on populations of freshwater turtles. It is in many ways a work in landscape ecology, but with components of spatial ecology, habitat selection, and population genetics. Chapter 1 is a stand-alone, opportunistic study of the effects of a small forest clear-cut on a population of spotted turtles (Clemmys guttata). We conducted a radiotelemetry study for one year before, and one year after a 3-ha forest clear-cut in close proximity to wetlands known to contain a resident population of the species. The annual home range size of turtles was 18.5% larger post-cut, possibly due to changes in the distribution of resources and suitable habitat after the harvest. However, turtles exhibited fidelity to hibernacula and communal hibernation despite nearby disturbance, and patterns of activity and habitat use were similar in both years and were generally consistent with those of other spotted turtle populations. Our results suggest that timber harvesting of this spatial scale and management approach may not have any short-term effects on the spatial ecology or habitat use of populations of spotted turtles. It is a strong caveat though, that further research is needed to understand longer-term effects. Chapters 2, 3 and 4 consist of data collected during a state-wide sampling effort of freshwater turtles in small, non-riparian wetlands across a gradient of forest cover. By systematically and intensively sampling 88 randomly selected wetlands across this gradient, we intended to capture the variability in landscape composition and configuration found in Rhode Island and determine how this variability is related to species distribution, abundance, demography, and population genetic structure. In Chapter 2 we report abundances based on capture per unit effort, and use occupancy analysis to determine which among a suite of environmental and within-wetland covariates are driving species occurrence. Eastern painted turtles (Chrysemys p. picta) and snapping turtles (Chelydra serpentina) were widespread (occurring in 83% and 63% of wetlands, respectively), relatively abundant, and exhibited wide niche breadth. Spotted turtles were far less