Head-starting as a management component for gopher tortoises (Gopherus polyphemus)
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Published source details
Tuberville T.D., Norton T.M., Buhlmann K.A. & Greco V. (2015) Head-starting as a management component for gopher tortoises (Gopherus polyphemus). Herpetological Conservation and Biology, 10, 455-471.
Published source details Tuberville T.D., Norton T.M., Buhlmann K.A. & Greco V. (2015) Head-starting as a management component for gopher tortoises (Gopherus polyphemus). Herpetological Conservation and Biology, 10, 455-471.
Actions
This study is summarised as evidence for the following.
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Release reptiles born/hatched in captivity from wild-collected eggs/wild-caught females without rearing Action Link |
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Head-start wild-caught reptiles for release: Tortoises, terrapins, side-necked & softshell turtles Action Link |
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Translocate adult or juvenile reptiles: Tortoises, terrapins, side-necked & softshell turtles Action Link |
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Release reptiles born/hatched in captivity from wild-collected eggs/wild-caught females without rearing
A replicated study in 2007–2010 in open mixed pine forest in Georgia, USA (Tuberville et al. 2015) found that approximately a quarter of captive-born gopher tortoise Gopherus polyphemus hatchlings from wild-collected eggs initially released into predator-proof cages, and then into the wild on an island, survived the first year. Results were not statistically tested. In three consecutive years, survival rates of captive-born hatchling gopher tortoises released into predator-proof cages were 20–29% (178 tortoises in total) in the first year following release. In 2007–2009, gopher tortoise eggs were collected from the wild (from nests or gravid females), or private collections and incubated at 28–30°C. After emergence, 178 gopher tortoise hatchlings were released shortly after hatching into temporary predator-proof release cages (190 cm long x 122 cm wide x 33 cm high, 10–15 individuals/cage) near to abandoned burrows on a 5,670 ha island. Hatchlings remained in cages for two–four weeks before being released. All hatchlings were monitored by live trapping for two weeks in September–October 2007–2010 as well as opportunistically during other trapping exercises in the same years.
(Summarised by: Katie Sainsbury)
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Head-start wild-caught reptiles for release: Tortoises, terrapins, side-necked & softshell turtles
A replicated, site comparison study in 2002–2010 in two open mixed pine forests in South Carolina and Georgia, USA (Tuberville et al. 2015) found that survival rates of released head-started gopher tortoises Gopherus polyphemus were extremely variable in the first year following release, but consistently improved in the second to fourth years. Results were not statistically tested. Across three groups of released head-started tortoises, 3–100% survived the first year in the wild (2002 group: 17 of 32, 53% individuals survived; 2006: 7 of 7, 100%; 2007: 1 of 32, 3%). Survival rates improved overall in the subsequent three years after release (2002 group: 82–93%; 2006: 100%; 2007: 100%). In total, 97–100% of head-started gopher tortoise hatchlings survived the captive rearing period. In 2002, 2006 and 2007, head-started gopher tortoise hatchlings were released into two sites (2002: 32 hatchlings in an 80,000 ha forest reserve; 2006 and 2007: 7–32 hatchlings, released on a 5,670 ha island). Hatchlings were head-started in climate-controlled indoor enclosures from the autumn after hatching until the following spring, when they were released into enclosures (one/site) with artificial burrows. Enclosures were removed approximately six months later. Hatchlings were monitored by live trapping for two weeks in September–October 2002–2006 (forest reserve site) and 2006–2010 (island site).
(Summarised by: Katie Sainsbury)
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Translocate adult or juvenile reptiles: Tortoises, terrapins, side-necked & softshell turtles
A replicated study in 2001–2006 in open mixed pine forest in South Carolina, USA (Tuberville et al. 2015) found that just under a third of translocated gopher tortoises Gopherus polyphemus held in temporary enclosures for six months survived four years after release and that survival rates tended to be similar to head-started tortoises. Results were not statistically tested. In the first four years after release from temporary enclosures, translocated juvenile gopher tortoises had annual survival rates of 57–81%, compared to 53–93% annual survival for head-started juvenile gopher tortoises. Over the same time period, cumulative survivorship was at least 29% for translocated tortoises compared to 38% for head-started tortoises. In August–September 2001, thirty-five juvenile gopher tortoises (ages: 1–9 years) were translocated to an 800 km2 forest reserve and initially held in small enclosures for six months and provided with artificial starter burrows and food (11–12 juveniles/enclosure, each enclosure 3.5 m diameter) until their release. Thirty-two hatchlings taken from nests at the same donor site as the translocated tortoises were head-started in climate-controlled conditions from September 2001 to June 2002 (see original paper for details) and then released into a 1 ha enclosure with starter burrows until September 2002, when the enclosure was removed. Tortoises were monitored by live trapping in autumn and spring 2002–2006.
(Summarised by: Katie Sainsbury)
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