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Conservation of the Spotted Turtle (Clemmys guttata): Identifying Critical Demographic and Environmental Constraints Affecting Viability

Harms, Hillary Morgan
http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1213634295

Abstract Details

2008, Doctor of Philosophy (Ph.D.), Bowling Green State University, Biological Sciences.
The Spotted Turtle, Clemmys guttata, is a freshwater turtle species currently protected throughout most of its range. Urgent conservation action is warranted to assess population viability and to focus management for this species. This body of work is premised on four overarching questions which addressed the population viability, current population status, critical environmental variables, and management strategies. We performed sensitivity analyses utilizing demographic data from the literature incorporated into an age-based population model. We conducted a mark-recapture study at two study sites in the Oak Openings Region of northwest Ohio to assess the habitat and population characteristics of Spotted Turtles. We used presence and absence locations to identify critical environmental variables at the local and landscape scales, resulting in a habitat suitability model. Our sensitivity analyses identified the variables most influential to Spotted Turtle viability (i.e., survival rates of older age classes, population size, and age at reproduction). We found that Spotted Turtle density was higher than those reported in recent literature and that age structure was not as adult biased as many other populations. In general, turtles were using areas within sites that had higher water and taller, denser ground vegetation. At the local scale, turtle presence could be explained by low slope, higher levels of June moisture, and intermediate levels of March brightness. At the landscape scale annual solar radiation, June brightness, land cover, June NDVI, and slope were significant in explaining turtle presence. A habitat suitability map was created to locate other potentially suitable areas within the Oak Openings Region. Based on these results, the variables found to influence Spotted Turtle population persistence over time should be the focus of future field work and monitoring throughout the range. Local management should focus on managing current sites since Spotted Turtles show high site fidelity, but also to acquire additional lands since potential habitat makes up less than 1% of the region. We have shown that Spotted Turtles have complex habitat requirements, making it important to have a multiscale view which considers the context of different environmental variables that accommodate the year round requirements for turtle viability.
Karen Root, PhD (Advisor)
Juan Bouzat, PhD (Committee Member)
Enrique Gomezdelcampo, PhD (Committee Member)
Helen Michaels, PhD (Committee Member)
Candace Archer, PhD (Committee Member)
110 p.
Biology; Ecology; Management
spotted turtle; Clemmys guttata; population model; habitat model; density

Recommended Citations

Citations

  • Harms, H. M. (2008). Conservation of the Spotted Turtle (Clemmys guttata): Identifying Critical Demographic and Environmental Constraints Affecting Viability [Doctoral dissertation, Bowling Green State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1213634295

    APA Style (7th edition)

  • Harms, Hillary. Conservation of the Spotted Turtle (Clemmys guttata): Identifying Critical Demographic and Environmental Constraints Affecting Viability. 2008. Bowling Green State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1213634295.

    MLA Style (8th edition)

  • Harms, Hillary. "Conservation of the Spotted Turtle (Clemmys guttata): Identifying Critical Demographic and Environmental Constraints Affecting Viability." Doctoral dissertation, Bowling Green State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1213634295

    Chicago Manual of Style (17th edition)

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© 2008, all rights reserved.
This open access ETD is published by Bowling Green State University and OhioLINK.