Translocate adult or juvenile reptiles: Lizards
Overall effectiveness category Awaiting assessment
Number of studies: 17
Background information and definitions
Translocations involve the intentional capture, movement and release of wild-caught reptiles into the wild to re-establish a population that has been lost, or to augment an existing population. This can reduce the risk of inbreeding; help safeguard small populations from extinction due to catastrophic events and/or increase the occupied range. Translocations can also be used to move reptiles to areas where threats have been removed, such as islands where invasive predators have been eradicated. However, translocations are typically expensive and may risk spreading pathogens to previously unexposed areas.
Release techniques vary considerably, from ‘hard releases’ involving the simple release of individuals into the wild, to ‘soft releases’ that involve a variety of adaptation and acclimatisation techniques before release or post-release feeding and care.
This action includes studies which may combine different release techniques, but studies that explicitly test these different techniques are summarized separately under Use holding pens or enclosures at release site prior to release of wild reptiles; Use holding pens or enclosures at release site prior to release of captive-bred reptiles and Release reptiles into burrows.
This action includes the translocation of wild juvenile or adult reptiles. Relocations of eggs and nests, releases of captive bred individuals and releases of head-started individuals (reptiles of wild-origin reared in captivity prior to release) are discussed under: Relocate nests/eggs; Release captive-bred reptiles into the wild; Head-start wild-caught reptiles for release and Release reptiles born/hatched in captivity from wild-collected eggs/wild-caught females without rearing. For studies that release reptiles outside of their native range see Release reptiles outside of their native range.
Translocations that are carried out to mitigate against specific threats (for example translocating problem individuals away from a specific area, or translocating individuals away from development areas) are summarized under Mitigation translocations – Translocate problem reptiles; Translocate reptiles away from threats and Temporarily move reptiles away from short-term threats.
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; Tortoises, terrapins, side-necked & softshell turtles; Snakes; Crocodilians or Tuatara.
Supporting evidence from individual studies
A review of worldwide translocation programmes for reptiles during 1962–1990 (Dodd & Seigel 1991) found that one of eight lizard translocations were considered successful by providing evidence that a stable breeding population had been established. One translocation of one species was successful (sand lizards Lacerta agilis), two translocations of two species were unsuccessful (sand lizards, Saint Croix ground lizard Ameiva polops) and four translocations of four species had unknown outcomes (giant girdled lizard Cordylus giganteus, Galápagos land iguana Conolophus subcristatus, Anegada ground iguana Cyclura pinguis, sand lizards). Breeding was noted in two translocations of two species (Galapagos land iguana and sand lizards). The origin of individuals (wild populations or captive-bred) was not described for all programmes. Published and unpublished literature was searched.Study and other actions tested
A study in 1987–1993 on two islands near North Island, New Zealand (Towns 1994) found that translocating Whitaker’s skinks Oligosoma whitakeri to an island following removal of Pacific rats Rattus exulans and European rabbits Oryctolagus cuniculus resulted in some individuals surviving for at least five years and reproducing. Over a five-year period, 15 of 28 skinks (54%) were recaptured at least once, along with five offspring of translocated skinks. Trapping success ranged from 0.4 skinks/100 trap days (2.5 year after release) to 3.1 skinks/100 trap days (5 years after release, but larger area trapped). On another predator free island 25% of marked skinks were recaptured and trapping success was 0.3 and 0.9 skinks/100 trap days. In 1987, twenty-eight skinks (15 adults, 3 gravid females) were captured using pitfall traps on a predator-free island and translocated to the release island from February 1988 to March 1990. Each skink was released into an artificial burrow and stacks of plywood were provided as extra cover. Pitfall traps were placed in the release are (initially 49, increased to 69 traps over 580 m2) and were monitored twice/year.Study and other actions tested
A study in 1995–1998 on a mixed woodland, shrub and grassed island off the east coast of St. Lucia (Dickinson et al. 2001) found that a population of translocated St. Lucia whiptail lizards Cnemidophorus vanzoi survived at least three years after release and bred. Three years after translocation, the average size of a population of St. Lucia whiptail lizards was estimated to be 145 lizards, more than three times greater than the number of lizards originally released. In 1995, forty-two whiptail lizards taken from a nearby island were released on Praslin Island (1.1 ha). Lizards were surveyed in October–December 1997 and January–March 1998 along line transects and caught with a noose. Black rats Rattus rattus were eradicated from the island in 1993 but subsequently encountered there infrequently from 1995 onwards and were removed when discovered.Study and other actions tested
A before-and-after study in 1988–1998 on a tropical island in the Bahamas (Knapp 2001) found that a translocated population of Allen’s Cay iguana Cyclura cychlura inornata had grown over a 10-year period following release. Seven of eight iguanas from the original release were recaptured, as well as 28 descendants (11 males, 16 females). The total population was estimated at 40–107 individuals. In 1988–1990, eight iguanas (4 males and 4 females) were translocated to the island from a nearby population. In 1998, six days (2 each in March, May and November) of trapping were carried out and individuals were marked by clipping toes and painting numbers on both sides of the ribs using white correction fluid. Population size was then estimated by walking a 320 m linear transect three times every day for 24 days between March and November 1998 and noting all marked and unmarked individuals.Study and other actions tested
A study in 1987–1998 on a partially forested island in New Zealand (Towns & Ferreira 2001) found that after translocating three species of lizard, some individuals were still present 6–12 years later. Up to 38% of the released lizards disappeared in the first 12 months. Lizards had high annual survival (Cyclodina alani annual survival rate: 81% male, 88% female; Whitaker's skink Cyclodina whitakeri: 76% male, 77% female; egg-laying skink Oligosoma suteri: 87% male, 93% female), but adult populations did not increase (Cyclodina alani: 4 released, 6 captured after 7 years; Whitaker's skink: 18 released, 11 captured after 12 years; egg-laying skink: 30 released, 35 captured after 6 years). In 1987–1990, lizards (total released: 14, 28 and 30 lizards) were captured in pitfall traps from two islands and translocated to a nearby island where European rabbits Oryctolagus cuniculus and Pacific rats Rattus exulans had been removed. Lizards were translocated within 48 h of capture, except for 23 Whitaker's skink which were not released for two months. Post-release monitoring was conducted with baited pitfall traps set in spring (November or early December) and late summer (late February or March) and checked daily during a 3–7-day monitoring period.Study and other actions tested
A study in 1999–2001 on an island in Turks and Caicos (Mitchell et al. 2002) found that after the eradication of feral cats Felis catus, all translocated Turks and Caicos Rock Iguanas Cyclura carinata survived at least two months post release and that some were breeding one year later. All of the first group of translocated iguanas (25 individuals) survived at least two months and 10 individuals survived at least 3–4 months after being released. After 14 months, two hatchlings were observed on the island. An initial group of 25 iguanas was translocated from Big Ambergis to Long Cay island (111 ha) in November 1999. Subsequent translocations took place every 2–3 months thereafter (404 individuals translocated in total). All iguanas were individually marked with PIT-tags. Ten individuals per translocation were fitted with radio collars and radio tracked until the next translocation. Feral cats were removed from the island prior to iguana reintroduction in July 1999 using fish laced with 1080 poison bait (22% concentration, sodium monofluoroacetate) distributed at bait stations placed systematically across the island (every 25 m in parallel lines 50–100 m apart, 500 total bait stations). There were no signs of cats in November 1999. One cat was found in January 2000 and removed from the island.Study and other actions tested
Referenced paperMitchell N., Haeffner R., Veer V., Fulford-Gardner M., Clerveaux W., Veitch C.R. & Mitchell G. (2002) Cat eradication and the restoration of endangered iguanas (Cyclura carinata) on Long Cay, Caicos bank, Turks and Caicos Islands, British West Indies. Pages 206-212 in: C.R. Veitch & M.N. Clout (eds.) Turning the Tide: The Eradication of Invasive Species. IUCN SSC Invasive Species Specialist Group, Gland, Switzerland and Cambridge, UK.
A review of worldwide reptile translocation projects during 1991–2006 (Germano & Bishop 2009) found that a third were considered successful with substantial recruitment to the adult population. Of the 47 translocation projects reviewed (39 reptile species), 32% were successful, 28% failed and long-term success was uncertain for the remaining 40%. Projects that translocated animals due to human-wildlife conflicts failed more often (63% of 8 projects) than those for conservation purposes (15% of 38) and those for research purposes (50% of 5). Success was independent of the source of animals (wild, captive, and combination), life-stage translocated, number of animals released and geographic region (see original paper for details). Translocated animals were adults in 75% of cases, juveniles and sub-adults in 64% of cases and eggs in 4% of cases. Wild animals were translocated in 93% of projects. The most common reported cause of failure was homing and migration with the second most common reported cause being insufficient numbers, human collection and food/nutrient limitation all equally reported. Success was defined as evidence of substantial recruitment to the adult population during monitoring over a period at least as long as it takes the species to reach maturity.Study and other actions tested
A replicated study on two island off the north-eastern coast of North Island, New Zealand (van Winkel et al. 2010) reported that translocated Duvaucel’s geckos Hoplodactylus duvaucelii survived for at least a year after release and successfully bred. Authors reported that no mortalities were recorded in the first year after release and all recaptured individuals had improved body condition (no data provided). Offspring of the gravid released geckos were recorded after 12 months, and offspring from breeding events on the islands was recorded in 2012. A total of 39 wild geckos were captured on Korapuki Island (50:50 sex ratio) and quarantined for two weeks to test for diseases. All animals were tagged with PIT tags, and 20 geckos were fitted with radio-transmitters. Geckos were released in December 2006; with 19 released on Tiritiri Matangi (220 ha) and 20 on Motuora Island (80 ha). Geckos were monitored intensively in the year after release via a range of methods (including radio-tracking, spotlight surveys and checking funnel traps and artificial refuges), and annual monitoring was conducted thereafter.Study and other actions tested
Referenced papervan Winkel D., Marleen B., Barry M., Ji W. & Brunton D. (2010) Translocation of Duvaucel’s geckos to Tiritiri Matangi and Motuora Islands, Hauraki Gulf, as part of island ecological restoration initiatives. IUCN/SSC Re-introduction Specialist Group report, Global re-introduction perspectives: additional case-studies from around the globe, 113-115.
A replicated, controlled study in 2008–2009 in eucalypt forest in Western Australia, Australia (Christie et al. 2011) found that 10 of 12 translocated Napoleon’s skinks Egernia napoleonis survived at least four months, but all skinks released in restored mine sites moved to unmined forest within a week of being released. Ten of 12 translocated Napoleon’s skinks survived at least four months after translocation. One skink lost significant weight, was returned to its source site and was classed as a reintroduction failure. The fate of one skink was unknown as it lost its radio transmitter (the authors reported possibly due to a predatory attack). Of the 10 skinks that remained in the reintroduction sites, eight gained weight after release and two lost a small amount of weight (<1 g). Six of six Napoleon’s skinks translocated to restored mine sites moved into unmined forest within 7 days and settled in unmined forest after four months. In November 2008, twelve Napoleon’s skinks were released in three 5-year-old restored forest sites and three unmined forest sites (two skinks/site; see original paper for details of restoration). Skinks were radio-tracked weekly for the first four weeks after release and then monthly for the next three months. Skinks were recaptured and weighed monthly.Study and other actions tested
A replicated, controlled, before-and-after study in 2009 in grass, bare ground and tilled soil enclosures in southern Australia (Ebrahimi & Bull 2012) found that translocated Pygmy bluetongue lizards Tiliqua adelaidensis provided with artificial burrows and supplementary food were observed less often in bare ground habitat without artificial burrows than lizards that had access to artificial burrows but were not fed. Fed lizards were observed less frequently in bare ground habitat without artificial burrows on most days compared to lizards with the same access to artificial burrows but that were not fed and this effect became larger towards the end of the feeding period (see original paper for details). Fed lizards changed burrow less frequently (0.5 changes/day) compared to unfed lizards (1.1 changes/day). In total 16 lizards were captured and moved to a trial site in a zoo. Four lizards were released into four 15 m enclosed cages in November 2009. Cages contained short grass, bare ground and tilled soil. Artificial burrows were built from hollowed wooden poles (30 cm long, 3 cm diameter) pushed into grassy or tilled soil (82 burrows/cage). No burrows were present in the bare ground habitat. Lizards were fed mealworms daily in burrows for seven days in two cages and not fed in the other two cages, then no lizards were fed for two days before the feeding regime began again, but this time the previously unfed cages were fed daily for seven days and the other cages were not. Lizards were monitored by four surveillance cameras/cage during daylight hours from the second to seventh days of the feeding regime (12 days total).Study and other actions tested
A study in 2008–2010 in rock outcrops in mixed grass and shrublands in Otago, New Zealand (Whitmore et al. 2012) found that most translocated grand skinks Oligosoma grande survived the first year and bred in the wild. After one year, 10 of 10 juvenile skinks and five of nine adult skinks had survived. The population increased from 19 to 20 individuals. The authors reported that although the population had increased overall, it’s reproductive potential had declined due to the loss of adult skinks. In October 2009, nineteen grand skinks were moved 4 km from three source sites to a cluster of rock outcrops (0.25 ha) in a conservation reserve, where non-native predators had been controlled since 2008. Skinks were monitored every 7–15 days for the first 60 days and in December 2009, April 2010 and December 2010 using photographic surveys. Predators were controlled using traps (800 traps across 4,500 ha of the reserve).Study and other actions tested
A site comparison study in 2006–2008 on a sand and rock beach on an island in Hauraki Gulf, New Zealand (Baling et al. 2016) found that a translocated population of shore skinks Oligosoma smithi survived at least two years, but that colour pattern variation reduced from four to three pattern types. One–two years after 40 skinks were reintroduced, 29 shore skinks were captured. Four colour pattern types were present in the donor population and the originally translocated skinks, but after 1–2 years, only three colour types were present in the translocated population (see original paper for details). The authors reported that this may have been due to the darker and more vegetated habitats prevalent in the destination location. Forty shore skinks (including nine gravid females) were translocated from a coastal sand dune system and reintroduced to a non-native-predator-free island reserve (220 ha) in 2006. Shore skinks were considered extinct on the island prior to this release. Skinks were released on a dark sand beach with rocks and boulders on the east of the beach and low-level vegetation away from the shoreline. In February 2007–March 2008 skinks were monitored every three months at the source and destination location using 2–3 baited pitfall trapping grids for 3–6 trap nights at a time (see original paper for details). Skinks were photographed, assessed against the habitat background and individually marked prior to release.Study and other actions tested
A replicated study in 2000–2013 on an offshore cay in San Salvador, Bahamas (Hayes et al. 2016) found that two translocated populations of San Salvador rock iguanas Cyclura rileyi rileyi, survived at least seven years in the wild but there was only evidence of breeding in one population. At least two years after a first translocation, five marked San Salvador rock iguanas and one subadult were observed (confirming breeding had taken place in the wild) and three unmarked iguanas were trapped; after five more years, two adult iguanas were observed. The authors reported that no iguanas from this translocation had survived after 12 years. Seven years after a second translocation, 12 of 14 adult iguanas were still alive, but there was no evidence of breeding in the wild. The first translocation was unsanctioned and took place in November 2000 (or earlier) with at least five individually-marked iguanas translocated to a private resort. The authors reported that feral cats Felis catus, dogs Canis lupus familiaris and rats Rattus rattus were removed from the resort. The authors observed and trapped these iguanas in October 2002, June 2007 and interviewed resort staff about them in 2012. In February 2005 a second translocation of 14 adult iguanas from a neighbouring island took place. These iguanas were surveyed in June 2006 and 2007, January and May 2012, and June 2013.Study and other actions tested
Referenced paperHayes W.K., Cyril Jr S., Crutchfield T., Wasilewski J.A., Rothfus T.A. & Carter R.L. (2016) Conservation of the endangered San Salvador rock iguanas (Cyclura rileyi rileyi): population estimation, invasive species control, translocation, and headstarting. Herpetological Conservation and Biology, 11, 90-105.
A study in 1973 and 2002–2013 in sandy palm forest, scrub and rock cay in the Exuma Islands, south-eastern Bahamas (Iverson et al. 2016) found that a population of translocated Acklins rock iguanas Cyclura rileyi nuchalis survived at least 40 years in the wild and bred, although there was some evidence of a population decline in the last year of the study. A population of translocated Acklins rock iguanas fluctuated between an estimated 59–322 individuals 30–38 years after the founding animals were released. Between the 37th and 38th year after release, the population estimate reduced from 218 individuals to 59 individuals. The authors reported that this decline may have been the result of rat predation or poaching. The authors reported that in 1973, five Acklins rock iguana were released on a cay (3.3 ha) in the Exuma Cays Land and Sea Park. Iguanas were monitored by live catching or trapping during daylight hours in May 2002–2005 and May or June 2007–2013.Study and other actions tested
A review of studies in The Bahamas, Turks and Caicos Islands, Puerto Rico, Grand Cayman and British Virgin Islands (Iverson et al. 2016) reporting on known translocations of rock iguanas (Cyclura) found that eight of 13 translocated populations survived at least 5–20 years in the wild and four of 13 translocations were deemed as being successful or the population had established. Three translocated populations of rock iguanas survived at least 6–10 years, one population survived at least 11–15 years, one population survived at least 16–20 years, and three populations survived more than 20 years in the wild. One population was described as ‘reproducing’, another as ‘established’ and two more as ‘successful’. The outcome of one translocation was unknown. Between the 1960s and 2012, thirteen populations of eight different rock iguana species (Cyclura cychlura inornate, Cyclura cychlura figginsi, Cyclura rileyi nuchalis, Cyclura rileyi rileyi, Cyclura carinata, Cyclura nubila nubila, Cyclura lewisi and Cyclura pinguis) were translocated to different island locations. Founder populations ranged from “a few” to 800 individuals and one population comprised headstarted individuals (see original paper for details).Study and other actions tested
A review published in 2016 of lizard translocation projects in New Zealand during 1988–2013 (Romijn & Hartley 2016) found that most projects found evidence of breeding following release, but few found evidence of population growth. Forty-five of 53 (85%) translocations motivated by conservation had some post-release monitoring. Seven found evidence of population growth (more lizards found than released), 33 found that populations were smaller than the number released, at least 16 found evidence of breeding after release, and five resulted in complete failure (no lizards found). One translocation (of speckled skinks Oligosoma infrapunctatum) was later discovered to be at a location outside the species historic range. Some translocations involved wild animals and others captive bred (project success vs source of animals not stated). Published and unpublished literature were searched, and key people associated with each translocation were identified and contacted for further information. Translocations were considered to be motivated by conservation if the primary focus was to benefit the species or recipient site.Study and other actions tested
A study in 2016–2018 on a tropical island off the coast of Anguilla (ANT/ATE/STENAPA 2018) reported that at least one translocated lesser Antillean iguana Iguana delicatissima survived for at least two years after release. Eight iguanas survived for at least nine weeks after release, and authors reported that individuals continued to be resighted after that point, with one individual being recaptured two years after release. In 2016, a total of 11 iguanas were translocated from the mainland (Anguilla) to a nearby small island (Prickly Pear East; 32 ha). Eight iguanas were fitted with radio collars and relocated every week for nine weeks. Collars were then removed and monitoring was carried out on an ad hoc basis.Study and other actions tested
Referenced paperANT ., ATE . & STENAPA . (2018) Lesser Antillean iguana Iguana delicatissima conservation strategy and action plan for the northern Caribbean sub-region (Anguilla, St. Barthélemy, St. Eustatius), 2018–2023, Anguilla National Trust, Agence Territoriale de l’Environnement and St. Eustatius National Parks Foundation.