Drivers of Thermal Habitat Use in Turtles Studied Under Semi-Natural Conditions

Understanding which factors predict species sensitivity to climate change requires comparative studies conducted under standardized conditions. Reptiles are particularly vulnerable to climate shifts due to their reliance on external temperatures to regulate body temperature. As such, available environmental temperatures may influence their behavior as they seek more optimal conditions. In this study, we measured thermal habitat use in 73 individuals across nine turtle species housed under semi-natural conditions at a single location. Ambient temperatures within each enclosure were also recorded every 20 min for 3 months to determine the range of thermal options available, yielding over 650,000 data points. We then compared experienced habitat temperatures to environmental conditions across the native range of each species. Experienced habitat temperatures generally aligned with native conditions. However, several species-including Terrapene carolina, Chelonoidis denticulata, and Indotestudo elongata-experienced habitat temperatures near the lower limit of what was available in enclosures and showed little individual variation, suggesting limited capacity for behavioral adjustment under future warming. Experienced habitat temperatures differed among species and were influenced by body mass, but not sex. By providing the first large-scale, cross-species dataset on experienced habitat temperatures in turtles under standardized conditions, this study offers a framework for assessing thermal vulnerability and adaptive capacity in response to climate change. These findings also inform conservation efforts, including the design of captive environments that reflect species-specific thermal needs.