Date of Award
5-2015
Document Type
Thesis
Degree Name
Master of Science (MS)
Legacy Department
Wildlife and Fisheries Biology
Committee Chair/Advisor
Dr. Kyle Barrett
Committee Member
Dr. Robert Baldwin
Committee Member
Dr. Michael Dorcas
Abstract
Because rare and cryptic species can be difficult to locate, distribution maps for these species are often inaccurate or incomplete. Bog Turtles (Glyptemys muhlenbergii) are emblematic of this challenge. In fact, conducting surveys of known, historical, and potential Bog Turtle habitat is a specific need stated in the Bog Turtle Northern Population Recovery Plan and in most Comprehensive Wildlife Conservation Strategies of states within the southern range. Therefore we examined ways to better locate Bog Turtle habitat and Bog Turtles within that habitat. First we determined a detection probability for a standardized trapping method so we could effectively survey for Bog Turtles at sites with unknown occupancy status. A species distribution model (SDM) was then used to identify potentially suitable Bog Turtle habitat within the species' southern range. The SDM was ground-validated, using our trapping method, to assess its ability to locate suitable Bog Turtle habitat. At a local scale we then analyzed wetlands occupied and unoccupied by Bog Turtles to examine differences in their habitat characteristics and site history. We had a 0.19 average probability of detecting a turtle at a site during one trapping event, implying 15 trapping events at a site would minimize the probability of Bog Turtles being at a site but going undetected to 5%. Ground-validation of the SDM with this trapping method showed that the SDM greatly over-predicted the amount of suitable habitat. For example, of 196 wetlands in Georgia and South Carolina identified as suitable by the SDM and ground-validated, only 22 met criteria for suitable Bog Turtle habitat, and trapping of 17 of those suitable wetlands revealed only 2 to be occupied by Bog Turtles. At the local scale, a discriminant analysis showed that wetlands with Bog Turtles were distinguishable from those without based on area of the wetland, percent of the wetland that has emergent vegetation, percent of the wetland that is flooded by beaver or lake presence, and water pH. These results suggest that future work should focus on better understanding local scale characteristics distinguishing Bog Turtle wetlands, as current data resolution does not enable a SDM to be effective.
Recommended Citation
Stratmann, Theresa Sonja Margareta, "Finding the Needle and the Haystack: New Insights into Locating Bog Turtles (Glyptemys muhlenbergii) and their Habitat in the Southeastern United States" (2015). All Theses. 2176.
https://open.clemson.edu/all_theses/2176