The importance of including survival release costs when assessing viability in reptile translocations

Published source details Bertolero A., Pretus J.L. & Oro D. (2018) The importance of including survival release costs when assessing viability in reptile translocations. Biological Conservation, 217, 311-320.
Share Tweet Email

Actions

This study is summarised as evidence for the following.

	Action	Category
	Release captive-bred reptiles into the wild: Tortoises, terrapins, side-necked & softshell turtles Action Link

Release captive-bred reptiles into the wild: Tortoises, terrapins, side-necked & softshell turtles

A replicated study in 1987–2015 in sand dune and mixed forest habitats in Spain and Minorca (Bertolero et al. 2018) found that many captive-maintained, released Hermann’s tortoises Testudo hermanni hermanni survived and that survival rates of released tortoises increased three years after release. During the first two years after release, average survival rates of translocated tortoises were 44–90% in Spain (66 individuals) and 79–85% in Minorca (48 individuals). In the third year after release, survival rates of translocated tortoises in Spain (98%) were similar to wild-born tortoises (98%) but survival rates of translocated tortoises in Minorca (89%) were lower than wild-born tortoises (97%). Body condition of tortoises before release did not affect whether or not a tortoise was subsequently found dead or alive (see original paper for details). Tortoises were maintained in captivity, though their origin and total time in captivity was unknown. In Spain, 66 captive tortoises were released into a protected reserve in four batches: September 1987, May–August 1988, March 1997 and September 1998. In Minorca, 48 tortoises were released in March–April 2004. The amount of time tortoises had spent in captivity prior to release was unknown. Tortoises were monitored for 4–10 days a year (Spain: 28 years; Minorca: 14 years) using capture-mark-recapture surveys.

(Summarised by: Katie Sainsbury)