SREL Reprint #3232
Overwintering of Gopher Tortoises (Gopherus polyphemus) Translocated to the Northern Limit of Their Geographic Range: Temperatures, Timing and Survival
Brett A. DeGregorio1,2, Kurt A. Buhlmann1, and Tracey D. Tuberville1
River Ecology Laboratory, Drawer E, Aiken, South Carolina 29801 USA
Abstract: We examined overwintering behavior in gopher tortoises (Gopherus polyphemus) translocated to the northern periphery of their geographic range by using miniature temperature data loggers during 2 winters. All adult and juvenile tortoises monitored with temperature loggers survived overwintering; however, during the course of the study 2 translocated juvenile tortoises without temperature loggers died during winter months. Onset and termination of overwintering were not different between the 2 yrs and were not correlated with mean above-ground air temperature. Mean overwinter duration was 127 ± 9 d SD and 128 ± 13 d SD during 20022003 and 20042005, respectively. Tortoises experienced temperatures as low as 7°C and as high as 31°C while overwintering; however, most (12 of 15) tortoises experienced very little (< 1°C) mean daily temperature fluctuation despite air temperatures regularly dropping below 0°C and exceeding 20°C. The overall mean temperature of overwintering tortoises was 12.4° ± 0.8°C (20022003) and 12.6° ± 1.2°C (20042005). Large fluctuations in temperature occurred when tortoises actively basked, and half of the monitored tortoises did, particularly juveniles, which accounted for 42% of winter basking events. Our results suggest that, given timely access to suitable refugia at recipient sites, overwinter mortality of translocated adult individuals may be minimal.
Keywords: Reptilia; Testudines; Testudinidae; thermal ecology; conservation; translocation; gopher tortoise: Gopherus polyphemus; iButtons; dormancy; overwintering
SREL Reprint #3232
DeGregorio, B. A., K. A. Buhlmann, and T. D. Tuberville. 2012. Overwintering of Gopher Tortoises (Gopherus polyphemus) Translocated to the Northern Limit of Their Geographic Range: Temperatures, Timing and Survival. Chelonian Conservation and Biology 11(1): 84-90.