Rehabilitate and release injured or accidentally caught individuals: Tortoises, terrapins, side-necked & softshell turtles

Overall effectiveness category Awaiting assessment
Number of studies: 4
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Background information and definitions

Reptiles that are injured, sick or found in a weak condition are sometimes taken in by wildlife rehabilitators, to be treated and released back into the wild. Animals may be injured or weakened due to direct interactions with human threats, for example entanglement in fishing gear, or due to natural threats such as extremes of weather caused by climate change (for example sea turtles may become ‘cold-shocked’ due to sudden severe cold weather). Often rehabilitation is carried out more for animal welfare reasons than for species conservation. However, for rare species it may be essential to preserve populations and release of such animals may provide opportunities for choosing where to augment populations. The success of such programmes can be difficult to judge without benchmark data for survival of wild-reared reptiles. It is also important to note that some of the studies summarized below have small sample sizes, and that unsuccessful attempts are less likely to have been reported.

Due to the number of studies found, this action has been split by species group, though no studies were found for amphisbaenians. See here for: Sea turtles; Snakes & lizards; Crocodilians or Tuatara.

For studies evaluating the effect of releasing reptiles that were accidentally caught in fishing gear, see Threat: Biological resource use – Establish handling and release procedures for accidentally captured or entangled (‘bycatch’) reptiles and Release accidentally caught (‘bycatch’) reptiles.

Study locations

Key messages

Four studies evaluated the effects of rehabilitating and releasing injured or accidentally caught tortoises, terrapins, side-necked and softshell turtles on their populations. Two studies were in France and one was in each of South Africa and the USA.

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (4 STUDIES)

Reproductive success (1 study): One controlled study in France found that some rehabilitated Hermann’s tortoises were observed mating with resident tortoises following release.
Survival (4 studies): One controlled, before-and-after study in France found that survival of rehabilitated and released Hermann’s tortoises was similar compared to wild tortoises over a two-year period. Three studies (including two replicated studies) in South Africa, France and the USA found that Babcock’s leopard tortoises, Herman’s tortoises and ornate box turtles released following rehabilitation survived for varying durations during monitoring periods that ranged from three months to 25 months or until the end of the active season during the year of release.

BEHAVIOUR (2 STUDIES)

Behaviour change (2 studies): One controlled study in France found that 12 rehabilitated Herman’s tortoises remained within 2 km of their release site over a three-month period. This study also found that daily movement of rehabilitated and released tortoises was similar to residents. One controlled, before-and-after study in France found that rehabilitated tortoises released in autumn took longer to establish a home range than those released in spring.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

A replicated study in 2005–2007 in two savanna sites in northeast South Africa (Wimberger et al. 2009) reported that 22 Babcock’s leopard tortoises Stigmochelys pardalis babcocki from a rehabilitation centre survived for between one and at least 25 months following release in to the wild. One tortoise survived for at least 25 months and two for 13 months. Eight tortoises were found dead 2–17 months following release. Seven were seen alive 1–17 months following release and then not seen again, and 11 were not re-seen at all. Tortoises for the release came from a rehabilitation centre. One had been confiscated from the traditional medicine trade, and the others were escaped pets. Twenty-two tortoises were released (11 males, 11 females) in January 2005, five (3 females, 2 males) in December 2006, and a further two females in February 2007. In total, 17 were fitted with radio trackers. Radio tracked tortoises were located monthly for 10 months after release, and then sporadically up to 25 months after release.
Study and other actions tested
Referenced paper
Wimberger K., Armstrong A.J. & Downs C.T. (2009) Can rehabilitated leopard tortoises, Stigmochelys pardalis, be successfully released into the wild? Chelonian Conservation and Biology, 8, 173-184.
A controlled study in 2012–2013 in mountainous grasslands in Provence-Alpes-Côte d'Azur region, southwest France (Lepeigneul et al. 2014) found that 12 released rehabilitated Herman’s tortoises Testudo hermanni hermanni survived at least three months in the wild and bred. After 3 months, all 12 released rehabilitated tortoises remained within 2 km of their release site and moved similar daily distances (27–38 m/day) to resident tortoises monitored at the same time (34–40 m/day). The authors report that female released tortoises were observed mating with male resident tortoises on several occasions. Twelve radio-tagged Herman’s tortoises were released directly into a national nature reserve (165 ha) in April 2013. The released tortoises were wild individuals that had been rehabilitated and maintained in captivity in a rescue facility in naturally-vegetated outdoor enclosures (7 m x 7 m) for 2–8 years prior to release. Released tortoises were radio-tracked in April–July in 2013. Resident tortoises captured within 0.8 km of the release site were also monitored in April–July using radio-tags in 2012 (9 individuals) and 2013 (14 individuals). All tortoises were tracked daily and behaviours were observed from a distance.
Study and other actions tested
Referenced paper
Lepeigneul O., Ballouard J.M., Bonnet X., Beck E., Barbier M., Ekori A., Buisson E. & Caron S. (2014) Immediate response to translocation without acclimation from captivity to the wild in Hermann’s tortoise. European Journal of Wildlife Research (formerly Zeitschrift für Jagdwissenschaft 1955-2003), 60, 897-907.
A replicated study in 2008–2009 in three sites of grass and scrubland and an urban area in Texas, USA (Sosa & Perry 2015) found that some rehabilitated ornate box turtles Terrapene ornata ornata survived until the end of the activity season that they were released in. At the end of the active season, five of 17 adult and 12 of 22 hatchling/juvenile rehabilitated and released ornate box turtles were confirmed as still alive. One adult and five hatchling turtles were confirmed dead. The fate of 11 adult and five hatchling turtles was unknown. In 2008 and 2009, thirty-nine ornate box turtles (17 adults and 22 hatchlings/juveniles) were rehabilitated and released from a rescue centre to three natural and one urban locations. Turtles were radio-tagged prior to release and located 3–6 times/week during the active season, or until death or loss of a transmitter signal.
Study and other actions tested
Referenced paper
Sosa J.A. & Perry G. (2015) Site fidelity, movement, and visibility following translocation of ornate box turtles (Terrapene ornata ornata) from a wildlife rehabilitation center in the high plains of Texas. Herpetological Conservation and Biology, 10, 255-262.
A controlled, before-and-after study in 2012–2016 in mixed scrub and woodland in south-eastern France (Pille et al. 2018) found that Hermann tortoises Testudo hermanni hermanni that were rehabilitated and translocated had similar survival over two years compared to wild tortoises, and tortoises released in spring established home ranges more quickly than tortoises released in autumn. Average survival of rehabilitated, translocated tortoises (83–86%, 24 individuals) was similar to wild tortoises (93–100%, 31 individuals) in the two years after release. Autumn-released rehabilitated, translocated tortoises took longer to establish a home range (258 days) than those released in spring (139 days). Rehabilitated, translocated tortoises settled similar distances from release locations regardless of season of release (see original paper for details). In total 24 rehabilitated (with various injuries or rescued from urban developments) Herman tortoises were translocated in April 2013 (12 individuals) and October 2013 (12 individuals) and radio tracked. Twenty resident tortoises and 11 from another population were also radio tracked in the release area, and six were tracked from a separate population in 2012–2015.
Study and other actions tested
Referenced paper
Pille F., Caron S., Bonnet X., Deleuze S., Busson D., Etien T., Girard F. & Ballouard J.M. (2018) Settlement pattern of tortoises translocated into the wild: a key to evaluate population reinforcement success. Biodiversity and Conservation, 27, 437-457.

Please cite as:

Sainsbury K.A., Morgan W.H., Watson M., Rotem G., Bouskila A., Smith R.K. & Sutherland W.J. (2021) Reptile Conservation: Global Evidence for the Effects of Interventions for reptiles. Conservation Evidence Series Synopsis. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

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This Action forms part of the Action Synopsis:

Reptile Conservation

Related Actions

Actions	Effectiveness	Studies	Category
Head-start wild-caught reptiles for release: Tuatara Action Link	Awaiting assessment	2	Synopsis Link
Release captive-bred reptiles into the wild: Snakes & lizards Action Link	Awaiting assessment	10	Synopsis Link
Head-start wild-caught reptiles for release: Tortoises, terrapins, side-necked & softshell turtles Action Link	Awaiting assessment	18	Synopsis Link