Translocate adult or juvenile reptiles: Crocodilians

Overall effectiveness category Awaiting assessment
Number of studies: 2
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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; Lizards or Tuatara.

Study locations

Key messages

Two studies evaluated the effects of translocating crocodilians on their populations. Both studies were global.

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (2 STUDIES)

Abundance (2 studies): Two global reviews reported four of five crocodilian translocations and 15 of 47 reptile translocations resulted in stable or growing populations (included both wild-caught and captive bred animals).
Reproductive success (2 studies): One global review reported that breeding occurred in at least two of five crocodilian translocations (included both wild-caught and captive bred animals).

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

A review of worldwide translocation programmes for reptiles during 1962–1990 (Dodd & Seigel 1991) found that four of five translocations of crocodilians were considered successful by providing evidence that a stable breeding population had been established. Four translocations of four species were considered successful (American alligator Alligator mississippiensis, mugger Crocodylus palustris, saltwater crocodile Crocodylus porosus, and gharial Gavialis gangeticus) and the success of the other translocation was unknown (Nile crocodile Crocodylus niloticus). Breeding was noted in two of the translocation programmes (American alligator and gharial). 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
Referenced paper
Dodd C.K.Jr. & Seigel R.A. (1991) Relocation, repatriation, and translocation of amphibians and reptiles: are they conservation strategies that work? Herpetologica, 47, 336-350.
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
Referenced paper
Germano J.M. & Bishop P.J. (2009) Suitability of amphibians and reptiles for translocation. Conservation Biology, 23, 7-15.

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

All the journals searched for all synopses

This Action forms part of the Action Synopsis:

Reptile Conservation

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Translocate adult or juvenile reptiles: Snakes Action Link	Awaiting assessment	14	Synopsis Link
Translocate adult or juvenile reptiles: Sea turtles Action Link	Awaiting assessment	2	Synopsis Link
Release reptiles into burrows Action Link	Awaiting assessment	1	Synopsis Link