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Survival, demography, and growth of gopher tortoises ( Gopherus polyphemus ) from three study sites with different management histories
Author(s) -
Tuberville Tracey D.,
Todd Brian D.,
Hermann Sharon M.,
Michener William K.,
Guyer Craig
Publication year - 2014
Publication title -
the journal of wildlife management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.94
H-Index - 111
eISSN - 1937-2817
pISSN - 0022-541X
DOI - 10.1002/jwmg.773
Subject(s) - carapace , ecology , biology , population , survivorship curve , habitat , predation , tortoise , wildlife management , wildlife , zoology , demography , crustacean , sociology
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, long‐term 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 (297 mm maximum carapace length [CL]) were smaller than the largest adults from Green Grove (337 mm CL) or Wade Tract (341 mm 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 short‐term and long‐term monitoring metrics to assess population recovery in such long‐lived species. © 2014 The Wildlife Society.