Date Approved
5-13-2025
Graduate Degree Type
Thesis
Degree Name
Biology (M.S.)
Degree Program
Biology
First Advisor
Jennifer Moore
Second Advisor
Patrick Laarman
Third Advisor
Alexandra Locher
Fourth Advisor
Joseph Jacquot
Academic Year
2024/2025
Abstract
To effectively manage wildlife populations, it is crucial to understand movement and space use dynamics. For semi-aquatic species that have temporally shifting habitat requirements, this understanding is even more important. The objective of this study was to assess home ranges, movement patterns, and habitat selection of spotted turtles (Clemmys guttata), a threatened species, in Michigan, USA. We used very high frequency radio-telemetry to track 20 turtles at two study sites and estimated home range sizes, movement patterns, and habitat selection across three years (2022, 2023, 2024). We found that the average 95% weighted autocorrelated kernel density estimated (wAKDEc) annual home range size for spotted turtles was 16.10 ha (SE ± 5.18) across all years. Neither sex nor body mass influenced home range size, but site and year were both significant factors. 95% minimum convex polygon (MCP) home ranges were close to those estimated in other spotted turtle populations across their range (3.99 ± 1.09 ha; mean ± SE). Non-random habitat selection occurred at both the second- and third-order at both sites. At the population level (second-order), mixed forest, palustrine scrub/shrub wetland, and palustrine forested wetland were the most preferred habitat types. At the home range level (third-order), non-random selection occurred at one site, with palustrine scrub/shrub wetland being the most preferred habitat type. Spotted turtles in Northwestern Michigan are highly dependent upon a variety of wetland habitats and they are sensitive to annual changes in environmental factors. The conservation implications of this study are important and show that spotted turtles at their northern range edge likely exist in small, isolated populations and rely heavily on seasonally dynamic wetland habitats that are vulnerable to changing climatic conditions. The results of this study can inform local and regional management plans for spotted turtle populations in similar habitats.
ScholarWorks Citation
Johnson, Caley, "Exploring the Spatial Ecology of Spotted Turtles (Clemmys guttata) at the Northern Extremes of Their Range" (2025). Masters Theses. 1150.
https://scholarworks.gvsu.edu/theses/1150
Comments
Grand Valley State University, United States Forest Service