Breeding biology of the critically endangered Malherbe’s parakeet on Maud Island, New Zealand, following the release of captive-bred individuals

Abstract

We studied a population of the critically endangered Malherbe’s parakeet (Cyanoramphus malherbi), following the release of 62 captive-bred individuals on Maud Island, New Zealand, to identify and characterise nesting sites in a novel island environment. Previous work on Malherbe’s parakeets consisted of limited observations on remnant mainland populations. The age of breeding pairs on Maud Island was 7.2 ± 4.7 months and included both captive-bred individuals of the first release flock and individuals hatched on Maud Island within a year of the first release. Nests were found in hollows of mamaku (Cyathea medullaris), vacant nests of sacred kingfisher (Todiramphus sanctus), a hole in the ground and a hollow in a kohekohe (Disoxylum spectabile). Active nests were found in the austral spring, summer and autumn. Clutch size was 5 eggs. The fledging of three Malherbe’s parakeets was confirmed for one nest 43 days after hatching. Observations of newly fledged individuals around the island indicate that at least seven successful nesting attempts occurred. Consistent with other studies in Cyanoramphus parakeets, our results suggest that availability of nesting sites on small islands may not be a limiting factor for the establishment of additional populations of Malherbe’s parakeets via captive breeding and translocation. The formation of breeding pairs at an early age, the use of diverse nesting sites in regenerating vegetation, and the evidence of successful breeding shortly after release on an island represent encouraging prospects for the conservation of New Zealand’s rarest parakeet.