Action

Translocate adult or juvenile reptiles: Tuatara

How is the evidence assessed?
  • Effectiveness
    not assessed
  • Certainty
    not assessed
  • Harms
    not assessed

Study locations

Key messages

  • Four studies evaluated the effects of translocating tuatara on their populations. Three studies were in New Zealand and one was global.

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (4 STUDIES)

  • Abundance (2 studies): One global review reported that 15 of 47 reptile translocations resulted in stable or growing populations (review included both wild-caught and captive bred animals). One study in New Zealand found that nine years after a translocation of 32 tuatara to an island where they had previously gone extinct, there was a population of 50 individuals.
  • Reproductive success (2 studies): One of two studies (including one controlled study) in New Zealand reported successful reproduction in one population of translocated tuatara. The other study reported no breeding during the six years following translocation.
  • Survival (2 studies): Two studies (including one controlled study) in New Zealand reported that 61–73% of translocated tuatara were recaptured over a six year period or survived for 9–12 month following release.
  • Condition (1 study): One controlled study in New Zealand found that translocated adult tuatara increased their body weight by 41% following release.

BEHAVIOUR (0 STUDIES)

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

  1. A controlled study in 1995–2000 on an island in New Zealand (Nelson et al. 2002) found that most translocated tuatara Sphenodon guntheri survived at least five years following release but did successfully breed. Eleven of 18 adults (61%) were recaptured over six years following release, as well as 28 of 50 head-started juveniles (56%). Following translocation, adults increased in weight by 41%, and two years after translocation they were heavier than equivalent length individuals from the founder population. No successful breeding was observed during the six-year period, though tuatara are an extremely long-lived species (up to 100 years). In November 1995, eighteen adults (11 females, 7 males) were translocated from North Brother Island to Titi Island (a rodent free island), along with 50 head-started juveniles. Tuatara were released into artificial burrows at night (2,100–2,230 h). Six post-release monitoring trips were conducted between November 1995 and November 2000, when a team of 3–4 people spent up to seven nights on the island searching for tuatara.

    Study and other actions tested
  2. A study in 1996–2005 on an offshore island in New Zealand (Towns 2005) found that a population of tuatara Sphenodon punctatus translocated to an island where invasive species had been eradicated survived at least nine years and bred. Numbers of tuatara were estimated to be approximately 50 individuals nine years after they were first released. At least two separate clutches of offspring (indicated by several different sized juveniles) were observed on the island. In 1996, thirty-two adult tuatara were translocated to Motuhora (Whale Island; 143 ha). European rabbits Oryctolagus cuniculus and black rats Rattus rattus were eradicated from the island using poison bait (Bromadialone, Brodifacoum and 1080 poison) and lethal traps in 1985–1987 (see original paper for details).

    Study and other actions tested
  3. 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
  4. A study in 2012–2013 in regenerating temperate forest in South Island, New Zealand (Jarvie et al. 2015) found that most translocated and captive-reared tuatara Sphenodon punctatus survived at least 9 months in the wild. After 3–6 months, all translocated and almost all captive-reared and released tuatara survived (translocated: 100%, captive-reared: 96–100% survival rate). After 9–12 months, survival rates of translocated tuatara (73%) were highest, followed by tuatara reared north of the release site (70%) and locally-reared and released tuatara survival rates were lowest (67%, result was not statistically compared). See original paper for comparisons of growth rates, post-release dispersal and home range sizes between wild-caught, locally-reared and north-reared tuatara. Juvenile tuatara originating from the same wild population were released into a predator-free fenced reserve in October–December 2012: wild-caught from an island 570 km north of the release site (14 individuals), captive-reared locally to the release site (13 individuals), and captive-reared 480 km north of the release site in a warmer climate (28 individuals). Captive-reared tuatara were hatched from artificially incubated eggs and head started until 4–6 years old. Artificial burrows were buried in the release area. Tuatara were monitored by radio-tracking for 5 months (10 wild-caught, 6 locally-reared, 10 north-reared individuals) and recapture surveys for up to 27 months after release.

    Study and other actions tested
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.

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Reptile Conservation

This Action forms part of the Action Synopsis:

Reptile Conservation
Reptile Conservation

Reptile Conservation - Published 2021

Reptile synopsis

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