Date of Award
Master of Science in Biological and Environmental Sciences (MSBES)
Environmental and Earth Sciences
Natural Resources Science
Wood turtle (Glyptemys insculpta) populations are declining throughout their geographic range and the species is listed as Endangered by the International Union for the Conservation of Nature. Population declines have resulted from habitat loss, road mortality, land use practices, and many other detrimental anthropogenic factors. This species has been studied in several parts of its geographic range, but its distribution in Rhode Island, a rapidly urbanizing state, is poorly understood. In 2021 and 2022, we surveyed 24 stream segments five times each to determine occupancy and detection probability for wood turtles in Rhode Island, USA. Visual surveys were conducted in forested upland and open areas adjacent to targeted streams to determine the extent of upland habitat used by wood turtles. Wood turtles were detected in and adjacent to 33% of streams surveyed and were estimated to occupy 0.46 (CI = 0.14-0.82) of these streams. We estimated a detection probability of 0.18 (CI= 0.06-0.41) for one hour survey if the species occupies a site and the detection probability increased with the number of surveyors (0.29). However, broad confidence intervals on occupancy and detection probability estimates limit inferences that can be made regarding explanatory covariates. We detected 21 unique wood turtles which constituted a density of 0.88 turtles per km of stream on all surveyed streams and 2.63 turtles per km of stream on occupied streams. In assessing movements away from streams, we found that most individuals (88%) were detected within 60 m of streams, however, some individuals were found >150 m from streams. In order to gain a finer resolution on the distribution of wood turtles in Rhode Island, we recommend increasing the number of surveys conducted on each stream and surveying additional streams throughout the state of Rhode Island.
Johnson, Chloe Nicole, "DISTRIBUTION OF WOOD TURTLE (GLYPTEMYS INSCULPTA) POPULATIONS IN RHODE ISLAND" (2022). Open Access Master's Theses. Paper 2281.
Available for download on Sunday, January 12, 2025