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 2002–2003 and 2004–2005, 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 (2002–2003) and 12.6° ± 1.2°C (2004–2005). 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.

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