Corticosterone secretion in response to capture and handling in free-living red-eared slider turtles

The corticosterone response to capture and handling was measured in free-living red-eared slider turtles, Trachemys scripta elegans. To determine the ability of this species to exhibit this endocrine response, slider turtles were bled at the time of removal from hoop nets and again at 30 and 60 min following capture to create plasma profiles of acute corticosterone secretion from individuals. Plasma corticosterone concentration increased significantly with handling time. The greatest rise in corticosterone was within the first 30 min following capture and handling, with this rate of increase declining over the next 30 min of restraint. There was no correlation between corticosterone levels at the time of capture and the length of time it took to get the sample if the sample was taken within the first 10 min after capture. However, when these samples were included with those taken from other turtles sampled 11 to 25 min after capture, hormone levels were significantly correlated with handling time. This suggests that the critical time to obtain an initial sample that best represents the predisturbance level in slider turtles is within 10 min. There was no correlation between the turtles' energetic condition and initial corticosterone concentrations. Plasma corticosterone values at all sampling times were comparable to those observed in other reptile species. The results from this study may be used to investigate the effects of unpredictable resources on reproductive success and survival in freshwater turtles.