Date of Graduation

Fall 2021


Master of Science in Biology



Committee Chair

Day Ligon


Turtles are perhaps best known for the bony shells that encase them, a unique morphological trait that provides protection against predators. Many taxa have even evolved the ability to enclose themselves using hinges that can be used to create a seal between the carapace and plastron. I measured the hinge closing force of Ornate Box Turtles (Terrapene ornata) to assess the performance of this unusual yet ecologically important trait. I sampled head-started turtles from Thomson Sand Prairie in the Upper Mississippi River National Wildlife and Fish Refuge and wild turtles collected in northern Oklahoma. To assess the effects of head-starting on predator defense, I compared hinge closure force, behaviors when threatened, and shell morphometrics between the two populations. Wild turtles typically closed immediately and with greater force than head-started turtles. The head-started turtles exhibited bolder behaviors and often were hesitant to seal themselves completely into their shells. Those that were head-started also had disproportionately long plastrons relative to wild turtles, a characteristic that tended to prevent them from creating a tight seal between the plastron and carapace. These results suggest that future head-start efforts should take steps to meliorate maladaptive morphological and behavioral consequences of captivity to maximize anti-predator measures following release.


conservation, head-start, reintroduction, animal behavior, turtle morphology

Subject Categories

Behavior and Ethology | Other Ecology and Evolutionary Biology | Zoology


© Gina L. Buelow

Open Access