Date Approved
5-7-2026
Graduate Degree Type
Thesis
Degree Name
Biology (M.S.)
Degree Program
Biology
First Advisor
Jennifer Moore
Second Advisor
Faith Kuzma
Third Advisor
Paul Keenlance
Academic Year
2025/2026
Abstract
With the widespread imperilment of turtle species, gaining understanding of how to effectively implement conservation strategies for struggling populations is vital. Headstarting has proven successful in many cases, but questions about maximizing post-release success remain. Which release method to use and what factors influence post-release survival are two pertinent issues this thesis serves to address. We carried out a hard and soft release of eastern box turtle (Terrapene carolina carolina) headstarts in southwest Michigan. Turtles were headstarted for nine months and released directly into the wild (i.e., hard released; n=15) or placed into an enclosure for five weeks before being fully released (i.e., soft released; n=15). We used radio telemetry for post-release monitoring. We compared growth, dispersal, movement, and survival between release groups and found no significant differences. Proportional habitat use differed between release groups likely due to exact release location. Due to headstart mortality at this site, we also wanted to gain a better understanding of what factors influence their survival. With data collected from 2020–2025 on 80 radiotracked eastern box turtle headstarts, we modeled survival using Cox proportional hazard regression. We recorded 27 mortalities over six years of monitoring, most (n=22) from predation. We evaluated release month, release weight, drought, precipitation, habitat use, movement, and dispersal as covariates. We found that headstarts released during non-drought conditions, moving less on average, or dispersing further from release site had a lower potential for mortality. Overall, soft release did not improve survival for our headstarts, but the context-dependent nature of soft release justifies experimentation at sites with high predation risk. Releasing headstarts during non-drought conditions and releasing them away from turtle nesting sites could effectively improve survival.
ScholarWorks Citation
Sweeney, Ava K., "Evaluating release strategies and survival of eastern box turtle headstarts" (2026). Masters Theses. 1181.
https://scholarworks.gvsu.edu/theses/1181
Comments
Research was conducted in collaboration with Pierce Cedar Creek Institute and John Ball Zoo.