Abstract & Overview
The eastern box turtle, Terrapene carolina carolina, is a terrestrial ectotherm that is vulnerable due to sustained population declines across its range in the Eastern United States. Where this species uses managed fields, conservation measures could be implemented to restrict field mowing until the local population enters into hibernation, and such mowing restrictions could be adjusted each year only if the precise timing of the entry into and emergence from hibernation could be predicted based on proximate environmental conditions. I monitored twenty turtles each winter over two years to determine movement and activity patterns at the William Floyd Estate, a management unit of Fire Island National Seashore in New York, USA. My objectives were to (1) identify environmental variables correlated with the timing of entry into and emergence from hibernation in order to inform local conservation measures relating to the timing of mowing and brush clearing activities, and (2) investigate whether physiological condition explained the broad variation in the timing of individual animals’ responses to the same environmental conditions. I determined the timing of entry into and emergence from hibernation using a combination of light sensors and temperature dataloggers and sampled blood from turtles in the second year before and after hibernation in order to measure plasma biochemical profiles. Cooler air temperatures were correlated with increased probability of entry into hibernation for any given week in the fall, while warmer air temperatures increased the probability of emergence from hibernation for any given week in the spring. Physiological condition was correlated with the number of days until immergence into hibernation in the fall. These findings indicate that environmental conditions are proximate cues that trigger the timing of hibernation and emergence in turtles, and that physiological condition may mediate these triggers by limiting or forcing responses. Based on these results, managers would benefit from using environmental monitoring to adjust the timing of mowing and brush clearing activities in order to take advantage of longer hibernation times during more severe winters or to limit risk to turtles during warmer falls or earlier onset of warming temperatures in the spring.