Date Approved
5-11-2026
Graduate Degree Type
Thesis
Degree Name
Biology (M.S.)
Degree Program
Biology
First Advisor
Jennifer Moore
Second Advisor
Paul Keenlance
Third Advisor
Eric McCluskey
Academic Year
2025/2026
Abstract
Turtles and tortoises are among the most imperiled vertebrate groups globally, with high extinction risks due to threats like habitat loss, poaching, climate change, and increased predation. As contributors to important processes such as nutrient cycling and seed dispersal, their conservation is essential for proper ecosystem functioning. Wood turtles (Glyptemys insculpta), a semi-aquatic freshwater species, are declining throughout their range due in large part to predation on adults by subsidized mesopredators such as raccoons (Procyon lotor). Because wood turtles are long-lived and slow to mature, populations require adult survival rates of at least 95% to remain stable or increase. Thus, while many conservation efforts focus on early life stages, protecting adults is essential for population persistence. Understanding when and where adult turtles are most vulnerable to predators is critical. To address this, we employed spatial ecological approaches to examine movement patterns of co-occurring wood turtles and raccoons in a managed landscape. During the summers of 2024 and 2025, we deployed high resolution GPS loggers on individuals of both species at a field site in northwest Michigan, USA. We assessed spatiotemporal overlap as a proxy for predation risk, generated a site-level risk surface, and explored trends between landscape variables and risk. Our results suggested that risk is highest in river corridors and lowland forests where turtles spend the most time and raccoons routinely forage. Risk also varied seasonally and between sexes, with males experiencing consistently higher exposure due to near constant use of risky river corridors, while females experienced periods of lower risk due to upland movements associated with nesting. These patterns indicate that predation risk in this system is largely driven by shared habitat use. Management actions such as maintaining structural complexity and refugia in riparian habitats, as well as targeted predator control, may help mitigate risk to adult wood turtles.
ScholarWorks Citation
Trimpe, Erin C., "Movement Ecology and Predation Risk: An Analysis of Co-occurring Raccoons and Wood Turtles" (2026). Masters Theses. 1190.
https://scholarworks.gvsu.edu/theses/1190
