Post-release movement and survivorship of head-started gopher tortoises

Published source details Quinn D.P., Buhlmann K.A., Jensen J.B., Norton T.M. & Tuberville T.D. (2018) Post-release movement and survivorship of head-started gopher tortoises. Journal of Wildlife Management, 82, 1545-1554.
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This study is summarised as evidence for the following.

	Action	Category
	Head-start wild-caught reptiles for release: Tortoises, terrapins, side-necked & softshell turtles Action Link

Head-start wild-caught reptiles for release: Tortoises, terrapins, side-necked & softshell turtles

A replicated, randomized study in 2013–2016 in two sites in a mixed pine forest in Georgia, USA (Quinn et al. 2018) found that less than half of released head-started gopher tortoises Gopherus polyphemus that were held in pens prior to release survived one year after release. In two consecutive years, less than half of head-started gopher tortoises survived for one year after release (year one: 5 of 12, 42% tortoises survived; year two: 13 of 30 43%). The authors reported that the primary cause of mortality was predation by mammals or fire ants and that 71% of all mortalities occurred in the first 30 days after release. In 2013–2014, wild tortoise eggs were collected and incubated in captivity, and hatchlings were head-started for 8–9 months indoors. In total, 145 tortoises (July 2014: 12 individuals; July 2015: 133 individuals) were released into two sites in a protected area (3,127 ha). Survival estimates were based on a subset of tortoises (2014: 11 individuals; 2015: 30 individuals) that were radio tracked for one year after release. Tortoises were placed in predator-resistant, enclosed holding pens (5–6 tortoises/pen, random groupings) for 4–47 days prior to release. Each pen contained 5–10 artificial burrows (30–40 cm deep). Release sites were sprayed with insecticide (AMDRO®) to remove fire ants up to a 3 m perimeter around the edge of release pens.

(Summarised by: Katie Sainsbury)