Translocate adult or juvenile reptiles: Tortoises, terrapins, side-necked & softshell turtles
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Overall effectiveness category Awaiting assessment
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Number of studies: 26
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Supporting evidence from individual studies
A replicated, randomized study in 1985–1987 in mixed pine and cabbage palm woodland in Florida, USA (Burke 1989) found that over a third of translocated gopher tortoises Gopherus polyphemus initially kept in holding pens survived at least two years after release and bred in the wild. In total 32 of 75 tortoises survived at least two years after release. One of three recaptured females was gravid and three tortoises less than a year old were captured two years after the original release. In 1985, a total of 75 tortoises were caught using bucket traps and translocated to a county park 25 km away. Tortoises had previously been present in the new location but they were no longer considered to be present at the time of release. Tortoises were individually marked and were randomly allocated to one of four holding pens (56 m2) for 0–15 days prior to release. An additional 10 tortoises were released in 1986. Tortoises were recaptured in 1986 and 1987. Female tortoises were x-rayed to check for gravidity.
Study and other actions testedA review of worldwide translocation programmes for reptiles during 1962–1990 (Dodd & Seigel 1991) found that none of the five translocations involving tortoises and snapping turtles (Chelydridae spp. and Testudinidae spp.) were successful. One of five translocations was unsuccessful (desert tortoise Xerobates agassizii) and four of five had unknown outcomes (gopher tortoise Gopherus polyphemus, Galápagos giant tortoises Geochelone elephantopus, Aldabra giant tortoise Aldabrachelys gigantea and alligator snapping turtle Macrochelys temminckii). Breeding was noted in three of the programmes (Galápagos giant tortoise, Aldabra giant tortoise, gopher tortoise). 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 Published and unpublished literature was searched.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 testedA study in 1989–1992 in a freshwater lake in north-west Italy (Gariboldi & Zuffi 1994) found that some translocated European pond turtles Emys orbicularis released initially into a holding pen (with other associated actions) survived at least three years but there was no evidence of breeding in the wild. Twenty-nine of 41 translocated European pond turtles placed initially in a holding pen were observed at least once in the first four months following their release. Three years after release, at least six of 45 turtles were observed near the release site and a further four turtles were regularly seen 4 km away. No breeding activity was recorded. Fourteen turtles dispersed within two days of release and were not seen again. No dead turtles were found. In spring 1989 and spring 1990, forty-five individually marked European pond turtles were released into a temporary holding pen (13 m2 with an artificial pool of 3 m2) next to a freshwater lake (157 m long) in a protected area closed to the public (1989: 41 individuals, 1990: 4 individuals). Most turtles were released from the holding pen after three weeks (two turtles escaped). Turtles were fed at the release site for two weeks to minimise dispersal. Turtles were surveyed in June–September 1989 and periodically in 1990–1992 (no details of survey method are provided). No specific survival information for the 1990 releases is provided.
Study and other actions testedA study in 1990 in shrubland on Curieuse Island, Seychelles (Hambler 1994) found that a population of translocated Aldabra giant tortoises Aldabrachelys gigantea was still present on the island 12 years after translocation attempts began. A total of 117 tortoises (73 adult males, 38 adult females and 6 juveniles) were found (0.4 tortoises/ha overall; 2 tortoises/ha in occupied areas) 12 years after the start of translocations. Thirteen nesting sites and 21 clutches of eggs were also found. At least five dismembered shells were discovered, and 9% of adults had peeling and flaking shells. Around 250 tortoises were translocation to Curieuse Island between 1978–1982 (95 in 1978; 78 in 1980; around 80 in 1982). In July–October 1990, exhaustive surveys were conducted across the whole of the island and tortoises numbered with paint.
Study and other actions testedA study in 1994 in one reserve in southeast Madagascar (Boullay 1995) reported that translocated radiated tortoises Geochelone radiata survived and some mated following release. No mortalities were recorded, and numerous mating events were observed up to a maximum of one year following the release. In May 1994, a total of 169 radiated tortoises (107 females and 62 males) were released at the reserve site. Tortoises came from customs seizures by officials on Réunion Island.
Study and other actions testedA study in 1982–1988 in one large pond in Massachusetts, USA (Haskell et al. 1996) found that no translocated northern redbelly turtle Pseudemys rubriventris hatchlings survived, whereas some head-started turtles survived at least 3–13 years. Zero of 15 translocated hatchlings were re-captured. Larger head-started turtles had the highest annual survival in the first year following release (<65 mm: 36%; 66–95 mm: 66%; ≥96 mm: 92%), but annual survival in year 2–3 following release were similar for all sizes (60–100%). In 1982, fifteen hatchlings were translocated immediately after capture from a nearby pond. In 1979–1988, sixty-eight head-started turtles were released into the same location. Extensive trapping was carried out for 10 years following the release of the translocated hatchlings.
Study and other actions testedA replicated study in 1980–1999 in five upland sites near to New York, USA (Cook 2002) found that of eight translocations of turtles, at least three resulted in established populations. Three translocations of three species (common snapping turtle Chelydra serpentina, eastern painted turtle Chrysemys picta picta, eastern box turtle Terrapene carolina carolina) resulted in established populations and a further two translocations of two species were likely to have been successful (eastern painted turtle, eastern box turtle) based on persistence of offspring records. The success of the other three (common snapping turtle, eastern mud turtle Kinosternon subrubrum, spotted turtle Clemmys guttata) could not be assessed because of insufficient data. In 1980–1995, five species of locally caught turtles of different life stages were translocated to one or two sites. At one of the sites, coarse woody debris and some temporary and permanent freshwater ponds were also added. Monitoring involved funnel traps, drift-fences with pitfall traps, artificial coverboards, visual searches and radio-telemetry.
Study and other actions testedA controlled study in 1995–1997 in a forested, lowland protected area in Southwest Region, Cameroon (Lawson 2006) reported that a translocated forest hinge-back tortoise Kinixys erosa and two translocated Home's hinge-back tortoises Kinixys homeana survived for at least 63–443 days following release and had similar home range sizes to resident tortoises. Results were not statistically tested. The forest hinge-back survived for at least 372 days, and the Home’s hinge-backs for at least 63 and 443 days following release. Home ranges were 3–15 ha for translocated tortoises and 3–48 ha for resident tortoises. In April–June 1995, three wild-caught tortoises (one forest hinge-back and two Home’s hinge-backs) were obtained from local collectors and translocated to the study site, and in June–November 1995, six resident tortoises (three forest hinge-backs and three Home's hinge-backs) were found within the study site to monitor. All tortoises were fitted with radio-transmitters, attached to the rear edge of the top shell. Tortoises were located as often as possible in 1995, around twice/month in 1996, and around once/month in 1997. Recorded locations were used to calculate the home range size.
Study and other actions testedA controlled study in 2004–2005 in a mixed-forest site in North Carolina, USA (Hester et al. 2008) found that translocated eastern box turtles Terrapene carolina had lower survival than resident turtles. Fewer translocated turtles survived at least one year than residents (translocated: 5 of 10; resident: 10 of 10). Translocated turtles moved similar distances overall but had larger home ranges than residents in three of three measures (see paper for details). In May and June 2004, ten female turtles were translocated to randomly selected locations within the release site (1–38 km from their point of capture). Ten resident female turtles were also captured, and all turtles were fitted with radio transmitters (attached to shell). Turtles were radio-tracked every two to three days during active periods (May to October 2004; March to June 2005) and once/week during hibernation periods (October 2004 to March 2005) for one year post-release.
Study and other actions testedA 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 testedA study in 2005–2007 in the Omayed Protectorate, Egypt (Attum et al. 2010) found that approximately a fifth of translocated Egyptian tortoises Testudo kleinmanni survived two years after being released. Two years after Egyptian tortoises were released, 21 of 109 tortoises were still alive. Eight tortoises were found dead during the two years after release. Dead tortoises had similar body mass to live tortoises (data presented as statistical model outputs). In September 2005, a total of 109 tortoises were released into a protected area (700 km2). The tortoises had been confiscated from illegal pet markets in May 2005 and were held in captivity for several months prior to release. Monitoring was carried out every 3 days (3–4 hours/day) in a 4 km area around the release site in May–October 2007 by searching for tortoises, following tracks and looking under vegetation.
Study and other actions testedA controlled study in 2008 in desert scrubland in California, USA (Esque et al. 2010) found that most translocated desert tortoises Gopherus agassizii survived at least eight months after release and had similar mortality rates to resident tortoises. Eight–nine months after being released, 268 of 357 translocated desert tortoises were still alive. Mortality rates of translocated desert tortoises (89 of 357 individuals died, 25%) was statistically similar to mortality rates of resident tortoises in the release area (29 of 140 individuals died, 21%) and resident tortoises outside of the release area (28 of 149 individuals died, 19%). In March-April 2008, a total of 571 desert tortoises were translocated from a military reservation to 14 widely separated, unfenced public lands (across a total area of 1,000 km2). Translocated tortoises (357 individuals), resident tortoises in the release areas (140 individuals), and resident tortoises outside of the release areas (149 individuals) were radio-tracked at least once a month in March–December 2008. Mortality rates are based on the radio-tracked tortoises only.
Study and other actions testedA study in 2007 in one mountain stream in Hebei Province, China (Shen et al. 2010) found that most translocated big-headed turtles Platysternon megacephalum survived for at least 3–8 months following release. Eleven of 16 turtles survived for at least 3–8 months between their release and the end of the study period. A further five turtles went missing sometime following release, though their transmitters were recovered (data not provided). In April–September 2007, sixteen wild-caught adult turtles (9 males, 7 females) were purchased from a turtle dealer and released in to the wild. They were fitted with radio trackers and monitored on 4–6 consecutive days, twice/month until November 2017.
Study and other actions testedA replicated study in 2007–2008 in one mixed forest in Jordan (Attum et al. 2011) found that translocated spur-thighed tortoises Testudo graeca survived at least 4–11 months, and most had similar range sizes to resident tortoises. Six of seven translocated tortoises survived for the whole 11-month study period, and one tortoise was lost after four months when the transmitter failed. The average range size of translocated tortoises that were tracked for 11 months (6 ha, excluding for one female who ranged 98 ha) was similar to resident tortoises (6 ha). Seven tortoises were confiscated from tortoise sellers, and in June 2007, they were equipped with radio transmitters and released at one release site. Two resident tortoises were fitted with transmitters in October 2007 and February 2008. Translocated tortoises were released just prior to the aestivation period in August–September. All tortoises were located three times/week for 4–11 months following release.
Study and other actions testedA replicated, controlled, before-and-after study in 2007–2009 in four sites of desert scrub in California, USA (Drake et al. 2012) found that translocated desert tortoises Gopherus agassizii did not have elevated levels of stress hormone compared to wild tortoises. There were no differences in stress hormone (corticosterone) levels between translocated (males: 4–12 ng/mL; females: 3–12 ng/mL) and resident tortoises within release sites (males: 3–12 ng/mL, females: 2–10 ng/mL) or residents outside release sites (males: 3–10 ng/mL; females: 3–11 ng/mL), but overall stress levels did vary between years (2007: 4ng/mL; 2008: 9 ng/mL; 2009: 6 ng/mL). In March 2008, translocated tortoises (45 tortoises: 18 females, 27 males) were released into four areas (1.6 km2 each) between 9–30 km from the point of capture. A further 179 tortoises (72 females, 107 males) resident in the translocated area were monitored that had home ranges within or outside of the release sites (numbers of each not provided). Levels of stress hormone were measured by taking monthly blood samples (1,793 blood samples in total) in April–October, 2007–2009 from translocated tortoises (19–43 individuals/year) and residents from within (34–43 individuals/year) and outside the release areas (19–48 individuals/year).
Study and other actions testedA replicated, controlled study in 2010–2011 in wetlands within an urban park Kentucky, USA (Attum et al. 2013) found that translocated musk turtles Sternotherus odoratus had similar post-release survival and movement as resident turtles. Nine of 10 translocated turtles survived the whole 10–11-month study period, compared to 10 of 10 resident turtles. Movement distance, activity area, number of wetlands used, and number of wetland shifts were also similar for translocated and resident turtles (see paper for details). Resident (7 males, 3 females) and translocated (4 males, 6 females, from sites 6–20 km from the release site) adult turtles were trapped between March–August 2010 using baited hoop nets. Radio transmitters were fitted to their shells, and resident turtles were released at point of capture and translocated turtles were randomly assigned one of four ponds and released. Turtles were tracked on 2–3 days/week during warm months and once/month during cool months until June 2011.
Study and other actions testedA replicated study in 2007–2008 along a river in southern Oklahoma, USA (Moore et al. 2013) found that most translocated alligator snapping turtles Macrochelys temminckii were not recaptured in the year following release. In the year of release adults were captured on 46 occasions (249 released) and one year following release adults were captured on 3 occasions. In comparison, individuals from a cohort of captive-bred juveniles were recaptured on 5 occasions (16 released) in the year of release and on 18 occasions the year after release (number of individuals not given). Seven turtles were confirmed to have died following release. Eight predated nests were found in 2007, seventeen in 2008, and one intact nest was found in 2008. Adult turtles (249 individuals) were originally wild-caught and were confiscated from a turtle farm and released in groups of 27–62 at seven pools adjacent to the river in April 2007. An additional 16 captive-bred juveniles were release at one location in June 2007. Turtles were recaptured with baited hoop nets in May–August 2007 and 2008.
Study and other actions testedA replicated, controlled study in 2012 in two sites of dry scrub and mixed, open forest in southern Georgia, USA (Bauder et al. 2014) found that some translocated gopher tortoises Gopherus polyphemus survived for at least a year and moved more than resident tortoises. Of translocated tortoises that were tagged, eight of 10 (site 1) and 10 of 11 (site 2) survived at least one year following release. Translocated tortoises moved more than resident tortoises (translocated female: 894 m, translocated male: 1,637 m; resident female: 237 m, resident male: 1,410 m), and for two measures of home range size, translocated tortoises had larger home ranges than residents (method 1: translocated: 0–147 ha; resident: 0–13 ha; method 2: translocated: 1–256 ha; resident: 0–64 ha). Thirty-two adult tortoises were trapped in August and September 2011 and split equally between two release sites. Tortoises were placed in circular enclosures (1 ha) in starter burrows (1 m long) and held for an average of 281 or 290 days. At each site, 10 and 11 translocated tortoises and eight and seven resident tortoises were fitted with radio transmitters. In June 2012, the enclosure fencing was removed and tortoises were located weekly until October 2012, and then every 1–4 months until June 2013.
Study and other actions testedA replicated study in 2007–2010 in a brackish reed marsh in southern France (Mignet et al. 2014) found that after translocating European pond turtles Emys orbicularis some survived for at least 1–2 years after release. Of 15 individuals released in 2008, twelve survived at least one year, and five at least two years. Of 14 released in 2009, eight survived at least one year. The home range of turtles the year after release (6 ha) was smaller than that of turtles in the year of their release (14 ha). In June–July 2007, thirty mature turtles were captured (30–70 km from release site) and placed in an acclimation enclosure at the release site. A group of 15 was released in April 2008 (10 females; 5 males), and a group of 14 in April 2009 (10 females; 4 males). Turtles were fitted with radio transmitters and were location twice/week for two months after release (May–June) and then once/week (July–October and March–September of the following year).
Study and other actions testedA replicated, controlled study in 2010–2012 in a stream and a wetland complex in Kentucky, USA (Attum & Cutshall 2015) found that of three releases of translocated red-eared slider turtles Trachemys scripta elegans, one population of spring-released sliders moved more and further afield than autumn-released or resident turtles, but that another population of spring-released sliders did not move more than resident turtles. Red-eared sliders released in spring into a stream moved more (total distance travelled: 8.6 km) and further away from the point of release (average distance from release: 1.4 km) than sliders released in autumn (total distance travelled: 3.8 km; average distance from release: 0.6 km) or resident sliders (total distance travelled: 4.6 km; average distance from release: 0.6 km). In a second translocation to a wetland complex, spring-released sliders had similar sized home ranges (6.3 ha) and travelled similar distances in total (4.5 km) compared to resident turtles (home range: 6.0 ha; total distance travelled: 3.8 km). Twenty-three sliders were translocated into a stream after hibernation in spring (March–May 2011 and 2012; 12 individuals) and before hibernation in autumn (October 2011, 11 individuals) from 20 km away and monitored in March 2011–October 2012 alongside 11 resident sliders (captured in May–October 2011). A further 13 sliders (captured May–August 2010) were translocated to a wetland complex and monitored alongside 13 resident sliders (captured April–June 2010) in May 2010–June 2011. All turtles were radio-tracked twice weekly in the activity season and once a month during hibernation.
Study and other actions testedA study in 2007–2010 in forested wetlands in eastern Massachusetts, USA (Buhlmann et al. 2015) found that at least one translocated hatchling Blanding’s turtle Emydoidea blandingii survived two years in the wild. One translocated and directly released Blanding’s turtle hatchling was incidentally recaptured two years later and had increased in size from 10g and 38 mm long at time of release (September 2008) to 105 g and 88 mm long on recapture (October 2010). In August 2007–2009, a total of 81 hatchlings from 36 nests at a source location were taken for direct release at a recipient wetlands refuge (reserve size: 880 ha).
Study and other actions testedA replicated, controlled study in 2009–2010 in a site of desert scrub in California, USA (Hinderle et al. 2015) found that translocated Agassiz’s desert tortoise Gopherus agassizii all survived and did not return to their home range if they were translocated more than 5 km from the capture site. All tortoises survived at least 37 days (40 individuals) or at least seven months (40 individuals). Nine of 47 translocated tortoises returned to their initial capture site (8 of 18 returned from 2 km; 1 of 15 returned from 5 km; 0 of 14 returned from 8 km) between five and 37 days after translocation. Tortoises were initially located and fitted with radio transmitters (80 individuals). In 2009, tortoises were translocated 2 km (10 individuals), 5 km (7 individuals) or 8 km away (6 individuals) from their capture location or released at their point of capture (17 individuals). In 2010, a further group of tortoises were translocated 2 km (8 individuals), 5 km (8 individuals) or 8 km away (8 individuals) from their capture location or released at their point of capture (16 individuals). In September–October 2009, tortoises were radio tracked for 37 days before being returned to their point of capture. In April–October 2010, tortoises were tracked for 186 days. Tortoises were located 2–7 times/week.
Study and other actions testedA 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.
Study and other actions testedA replicated study in 2008–2012 in desert shrubland in California, USA (Mulder et al. 2017) found that some translocated Agassiz’s desert tortoises Gopherus agassizii survived at least 4 years in the wild and bred, but that all hatchlings tested, including those from resident females, were sired by resident and not translocated male tortoises. Four years after being released, at least 13 translocated female Agassiz’s desert tortoises were found to have laid eggs. Of 34 clutches laid by translocated and resident female Agassiz’s desert tortoises, none of 35 hatchlings tested were sired by translocated male Agassiz’s desert tortoises. In spring 2008, a total of 570 tortoises (184 females, 293 males, 93 juveniles) were translocated to a 1,000 km2 area, which already had a population of resident tortoises. In April–July 2012, clutches laid by translocated (13 individuals) and resident (21 individuals) female tortoises were located and hatchlings (35 individuals) tested to establish paternity by comparing DNA against a reference database (which included 190 resident males and 305/386 translocated adult and juvenile males). If no significant match with the database was found, the authors assumed that an unknown resident tortoise was the sire. Both translocated (31 individuals) and resident male tortoises (37 individuals) were known to frequent the study area.
Study and other actions testedA controlled study (year not stated) in a woodland-wetland complex in Maryland, USA (Krochmal et al. 2018) found that translocated Eastern painted turtles Chrysemys picta had higher mortality than resident tortoises and did not navigate successfully from dry ephemeral ponds to alternative water sources, regardless of season of release. Mortality rates were higher in translocated turtles (early-season release: 10 of 20 turtles; late-season release: 2 of 30 turtles) compared to resident turtles (0 of 60 turtles). After ephemeral ponds dried, no translocated turtles successfully navigated to alternative water sources (within 21 days), although all resident turtles did (within 33 h). Translocated turtles deviated more widely from established turtle navigation routes regardless of release season (early-season release 74 m from route; late-season release: 86 m) compared to resident turtles (1 m). Translocated turtles spent more time stopped, moved slower, took longer to move after stopping and lost more body mass than resident turtles regardless of release season (see original paper for details). The translocation destination habitat included temporary ponds (3 ha each) which dry up within a day each summer. Early-season released turtles (20 individuals) moved 3 months (in April) before draining took place to allow time to learn to navigate the destination habitat before draining occurred, late-season released turtles (30 individuals) moved approximately 96 h before ponds drained (in July) and resident turtles (60 individuals) were monitored by radio telemetry every 15 minutes for 12 h/day, 7 days/week for at least 21 days (see paper for details).
Study and other actions testedA replicated study in 2016 on grassy roadside verges in east-central Florida, USA (Rautsaw et al. 2018) found that most gopher tortoises Gopherus polyphemus translocated short distances did not attempt to go back to their capture location. Only one of 13 translocated tortoises returned to its capture location (after one day in a single 2,058 m movement). All other translocated tortoises remained under vegetation on or near to the roadside verges where they were released and dug burrows (no data provided, see paper for details). Six tortoises (4 females, 2 males) were captured from inland habitats and seven (2 females, 5 males) from coastal habitat were translocated 2–4 km to a roadside corridor during summer 2016. The tortoises were radio tagged and tracked daily during the summer months (approximately 52 tracking events/tortoise) before recapture and return to their original location.
Study and other actions tested
Where has this evidence come from?
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This Action forms part of the Action Synopsis:
Reptile ConservationRelated Actions
| Actions | Effectiveness | Studies | Category | |
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Use holding pens or enclosures at release site prior to release of wild reptiles Action Link |
Awaiting assessment | 7 |
Synopsis Link |
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Translocate adult or juvenile reptiles: Tortoises, terrapins, side-necked & softshell turtles Action Link |
Awaiting assessment | 26 |
Synopsis Link |
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Release reptiles outside of their native range Action Link |
Awaiting assessment | 7 |
Synopsis Link |
Reptile Conservation - Published 2021
Reptile synopsis
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