Feasibility of immunocontraception for managing stoats in New Zealand.
Predation by mustelids, particularly stoats [Mustela erminea], is a significant threat to the persistence of many populations of endemic birds of New Zealand. Broadscale management of stoats is constrained by the associated risks to non-target species. Control methods that are more specific to stoats are laborious and costly. These methods can protect only a few threatened bird populations and only in small portions of habitat. Beyond these treated areas the declines of bird populations and extinctions past or imminent indicate a pressing need for more extensive management of stoats. New cost-effective methods for managing stoats over large areas are needed urgently. This study addresses that need by examining the literature to assess the potential for fertility control of stoats, especially immunocontraception, to contribute to the sustainable conservation of endemic New Zealand birds. Key recommendations are: * Use of current proven management techniques for stoats and other predators or pest prey should continue and be refined. * Consideration should be given to the development of a non-disseminating immunocontraceptive genetically modified organism (GMO) as the highest priority option for fertility control. * A robust bait attractive to stoats or mustelids and suitable for aerial delivery should be developed. * Chemosterilants currently have low species-specificity and further research into their use should have low priority. * The literature search for lethal biocontrol agents of stoats or mustelids did not reveal any outstanding candidates. Lethal biocontrol is a long-term research option and should have low priority. * Further ecological research is required to: - determine the reduction in stoat density required to protect species threatened by predation;.