CASH, W.B.*; HOLBERTON, R.L.: Stress and the Slider Turtle

We examined physiological and behavioral questions related to stress, locomotor activity and dispersal movement in the slider turtle, Trachemys scripta. Like many other vertebrates, slider turtles show a corticosterone response to capture and handling, characterized by an increase in plasma corticosterone concentration with handling time. In the laboratory, turtles implanted with exogenous corticosterone showed a significant increase in caged locomotor activity when compared to control animals with empty implants. In the field, the effects of the simulated drying of a pond on the behavior of T. scripta were measured. Turtles responded to the draining of a pond by the emigration of the majority (75%) of the experimental population. Turtles had significantly elevated corticosterone when compared to individuals captured in a control pond, where conditions were held constant. However, 25% of the experimental group did not emigrate from the pond, suggesting that there is natural variation in turtle populations when responding to habitat declines, like rapidly decreasing quality or availability. Finally, aspects of the annual cycles of corticosterone were studied in wild and laboratory-held slider turtles. Male sliders were found to exhibit both a change in baseline corticosterone and the ability to respond to handling stress throughout the period studied. Female sliders did not show a significant difference in their baseline corticosterone concentrations, but did show a difference in their stress response over the sampling period. These results show collectively that corticosterone is involved with the ability of slider turtles to respond to environmental disturbances and corticosterone may ultimately be the proximate mechanism facilitating a stress avoidance response.