SREL Reprint #3295

Survival, demography, and growth of Gopher Tortoises (Gopherus polyphemus) from three study sites with different management histories

Tracey D. Tuberville1, Brian D. Todd2, Sharon M. Hermann3, William K. Michener4, and Craig Guyer3

1University of Georgia’s Savannah River Ecology Lab, Drawer E, Aiken, SC 29802, USA
2Department of Wildlife, Fish, and Conservation Biology, University of California, Davis,
One Shields Ave, Davis, CA 95616, USA
3Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
4University Libraries, 1312 Basehart SE, Albuquerque, NM 87106, USA

Abstract: Recovery or sustainable management of wildlife populations often entails management of habitat on which they depend. In this regard, turtles pose unique conservation challenges because of their life histories. The combination of late maturity, low survival when young, and dependence on high adult survival suggests they may be slow to respond demographically to conventional habitat management. Thus, longterm studies are necessary to understand population dynamics and recovery potential in these species. We used 5–11 years of mark-recapture data from 3 populations to evaluate survivorship, demography, and somatic growth of gopher tortoises (Gopherus polyphemus). Green Grove and Wade Tract (southwest GA) are ecological reserves with a history of land management compatible with tortoises. In contrast, Conecuh National Forest (south-central AL) is a closed-canopy pine plantation with prior intensive site preparation but where management intervention improved habitat for tortoises during the study. Apparent survival was high for mature tortoises (87–98%) compared to immature tortoises (70–82%). Adults comprised 57–79% of individuals captured, with Green Grove and Wade Tract populations dominated by larger individuals but Conecuh having a more uniform size distribution. The largest adults captured at Conecuh (297mm maximum carapace length [CL]) were smaller than the largest adults from Green Grove (337mm CL) or Wade Tract (341mm CL), although characteristic growth constants from von Bertalanffy models were similar among sites. We suggest these results indicate a recovering population at Conecuh, where habitat conditions for gopher tortoises have improved despite a legacy of intense predation by humans and reduced habitat quality at the inception of this national forest. Further, we recommend using a combination of shortterm and long-term monitoring metrics to assess population recovery in such long-lived species.

Keywords: demography, gopher tortoise, Gopherus polyphemus, growth, habitat management, population recovery, survivorship

SREL Reprint #3295

Tuberville, T. D., B. D. Todd, S. M. Hermann, W. K. Michener, and C. Guyer. 2014. Survival, demography, and growth of Gopher Tortoises (Gopherus polyphemus) from three study sites with different management histories. The Journal of Wildlife Management 78(7): 1151-1160.

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