I might be able to provide a bit of information......
These small Cynaoramphus parakeets have been the subject of considerable conservation efforts over many years to try and reverse the population decline. In situ attempts to reduce predator numbers and increase productivity within mainland forests were only partially successful given the periodic plagues of predators (stoats and rats) that arrive following mast seeding events (which also trigger parakeet breeding activity). Subsequent strategies have largely revolved around the harvest of eggs/chicks from wild nests and the captive rearing and breeding of the resulting progeny (often using closely related species surrogates). Once 'sufficient' birds were raised (usually determined by the amount of aviary space) they have been released back into there mainland habitats or used to form the nucleus of new populations both on pest free offshore islands (without other parakeets) and the mainland. This has been something of a learning experience with more failures than successes but currently we seem to have at least one stable island population, one population on the mainland behind a 'predator-proof' fence and an original population within a Canterbury valley that has expanded significantly over the past few years. This latter population tends to oscillate quite a bit as they are a very boom and bust species that is relatively short lived.
The transfer/translocation process tends to follow a tried a true method. Birds bred in captivity are regularly harvested for transferred. The number until now has been restricted by aviary space but with the addition of new enclosures the numbers being released look likely to improve from approx 25 at a time to hopefully double this with up to two releases per season. There is a huge amount of work done by our partners to hold and raise these birds for release. These birds are then taken to the release site (usually flown) and released into large purpose built aviaries with a soft release occurring at an interval thereafter. A portion of the birds released are radiotagged using tail mounted VHF transmitters that will last only for a few weeks. All birds are colour banded. Supplementary feeding stations are established in the release vicinity with previously released parakeets used as anchors for the new comers. A high proportion of these released birds will used the supplementary food which is presented in feeders with which they are familiar and the feeders are also equipped with cameras that are able to record the band combinations. Experiments are currently under way to use PIT tags embedded in bands to try and automate the detection process to some degree.
Some birds will survive more that one year but this information is difficult to obtain and largely reliant on observations at feeders which some birds may not visit. This lack of detailed information on survival is obviously problematic but, I think, rather typical for many species. We are also aware that at least a few birds are capable of travelling considerable distance between watersheds in mountainous country so they are not all being released into oblivion. Natural nests, when located, are also protected as much as possible and the outcomes for these nests in conjunction with extensive pest control efforts (traps, terrestrial toxin delivery and aerial toxin delivery) are generally positive. Numbers have certainly increased but this takes considerable effort and is subject to breeding frequencies that are largely determined by mast events. Given the lessons learnt, our expanded ability to produce birds for release we hope to start a new mainland population within an alpine valley this season using the methods outlined above. I hope this fills in some of the information holes.
Department of Conservation, New Zealand