SREL Reprint #3381

Spring emergence of Eastern Box Turtles (Terrapene carolina): influences of individual variation and scale of temperature correlates

Brett A. DeGregorio1, Tracey D. Tuberville1, Robert A. Kennamer1, Bess B. Harris1,2,
and I. Lehr Brisbin, Jr.1

1University of Georgia’s Savannah River Ecology Laboratory, Aiken, SC 29802, USA
2Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission,
Gainesville, FL 32653, USA

Abstract: Many organisms spend considerable time in dormancy to avoid stressful environmental conditions. Understanding the timing and triggers of dormancy behavior is critical for understanding an animal’s life history and behavior. Eastern Box Turtles (Terrapene carolina (L., 1758)) avoid winter temperatures by burrowing into the soil and remaining dormant. Identifying the proximate environmental cues that trigger emergence can improve conservation efforts by reducing potential aboveground turtle mortality. During a 17-year study, half of all variation in emergence timing was attributed to individual variation and the habitat that they occupied during dormancy. We suggest that individual variation in emergence timing is common within populations and confounds efforts to identify reliable emergence cues. Additionally, the scale of meteorological data limits the ability to identify emergence predictors. Using data from temperature loggers placed at dormancy locations, we found that surface air temperatures, averaged over the 5 days prior to emergence, were more strongly related to emergence probability than any variables derived from local weather stations. Turtles generally did not emerge from dormancy until the 5-day mean surface temperatures measured at dormancy sites reached approximately 15°C. Our results suggest that individuals respond differently to environmental thresholds for emergence and individuals may be characterized as risk-taking or risk-aversive.

Keywords: emergence cues, Eastern Box Turtle, growing degree-days, dormancy ecology, individual variation, temperature, Terrapene carolina

SREL Reprint #3381

DeGregorio, B. A., T. D. Tuberville, R. A. Kennamer, B. B. Harris, and I. L. Brisbin Jr. 2017. Spring emergence of Eastern Box Turtles (Terrapene carolina): influences of individual variation and scale of temperature correlates. Canadian Journal of Zoology 95(1): 23-30.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).