Background information and definitions
Captive breeding is usually undertaken to provide individuals for release into the wild, either to reintroduce the species to part of their former range, or to increase the size of an existing population.
Amphibians possess a number of traits that make them potentially suitable for captive breeding and reintroduction programmes. They reproduce relatively quickly and their small size and low maintenance requirements allow viable populations to be managed much more cost-effectively than many larger animals. Also unlike higher vertebrates that possess many learned behaviours that may reduce survival in the wild, the hard-wired physiology and behaviour of amphibians means that pre- and post-release training are not required. However, before release consideration must be given to genetic management, health screening, acclimation of animals, long-term monitoring and involvement of local stakeholders.
Studies investigating captive breeding and release of specific groups of amphibians are discussed in separate sections. Studies investigating captive breeding are discussed in ‘Breed amphibians in captivity’.
Supporting evidence from individual studies
A review in 2008 of the effectiveness of 39 release programmes of captive-bred or head-started amphibians (Griffiths & Pavajeau 2008) found that 14 of 17 programmes that could be assessed were considered successful. Seven species (2 toad; 3 frog; 2 newt) showed evidence of breeding in the wild for multiple generations (high success), five species (3 toad; 2 frog) showed some evidence of breeding (partial success) and two species (1 toad; 1 frog) only showed evidence of survival following release (low success). Three programmes were considered unsuccessful and the outcome was not known for the other 19. Species from 16 countries were involved in these release programmes, with a bias towards temperate countries. Half of the species were classified in the top four highest IUCN threat categories (i.e. vulnerable to extinct in the wild).Study and other actions tested