Rehabilitate and release injured or accidentally caught individuals: Crocodilians

Overall effectiveness category Awaiting assessment
Number of studies: 1
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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; Tortoises, terrapins, side-necked & softshell turtles; Snakes & lizards 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

One study evaluated the effects of rehabilitating and releasing injured or accidentally caught crocodilians on their populations. This study was in India.

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (1 STUDY)

Reproductive success (1 study): One study in India found that found that breeding occurred in a rehabilitated and released population of mugger crocodiles four years after the first release.
Survival (1 study): One study in India found that seven of eight rehabilitated and released mugger crocodiles survived for at least 1–4 years after 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

A study in 1977–1981 in a river with a series of pools in Andhra Pradesh, India (Choudhury & Bustard 1982) found that accidentally captured mugger crocodiles Crocodylus palustris that were raised in captivity before being released survived for at least 1-4 years following release. At least seven of eight released crocodiles survived for at least 1–4 years after release. All crocodiles were re-sighted at the release site, or within 100–3,000 m away. Authors reported that the first breeding took place four years after the first release. In 1977–1980, eight mugger crocodiles (5 females and 3 males) were released following rearing in captivity. Crocodiles were between 1.1–1.9 m in length at the time of release. Prior to the release, grazing of cattle and goats along the river bank, fishing and use of the area for swimming and bathing were banned. After release, crocodiles were monitored by both research staff and by staff who were there to protect the release site.
Study and other actions tested
Referenced paper
Choudhury B.C. & Bustard R. (1982) Restocking mugger crocodile Crocodylus palustris (Lesson) in Andhra Pradesh: evaluation of a pilot release. Journal of the Bombay Natural History Society, 79, 275-289.

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

Related Actions

Actions	Effectiveness	Studies	Category
Release reptiles born/hatched in captivity from wild-collected eggs/wild-caught females without rearing Action Link	Awaiting assessment	5	Synopsis Link
Head-start wild-caught reptiles for release: Tuatara Action Link	Awaiting assessment	2	Synopsis Link
Use hormones and/or other drugs during captive-breeding programmes to induce reproduction/birth Action Link	Awaiting assessment	9	Synopsis Link