Conservation translocations and monitoring of kiwi : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University

Abstract

Translocations of kiwi (Apteryx spp.) are one of the most common and growing types of conservation translocations in New Zealand. However, their outcomes remain mostly unpublished, which does not allow for sharing of lessons learnt from past developments. We reviewed 102 kiwi translocations from the 19th century until 2018 and identified factors affecting their outcome. North Island brown kiwi (A. mantelli) was the most translocated species, but the highest impact of translocations on the improvement of conservation status was for the rarest taxa: little spotted kiwi (A. owenii), rowi (A. rowi), and Haast tokoeka (A. australis ‘Haast’). Translocations are typically used for creating secure populations and, more recently, for ecosystem restoration and meta-population management. We developed a set of criteria to evaluate the outcome of introductions and reintroductions based on demographic parameters alongside current recommendations on the genetic make-up of translocated populations. Based on these criteria, only a few translocated populations can be considered successful in the medium–long term: 15+ years following the release of a genetically diverse population (40+ unrelated individuals). Most historical translocations failed or require further genetic and habitat management. However, the majority of kiwi translocations have occurred over the last two decades and, while several populations have successfully established, for most of them, it is too soon to assess their medium-long term outcome. An analysis of factors affecting translocation outcomes revealed that, despite ongoing predator control, populations at small, unfenced sites on the mainland suffer from dispersal and predation, which has negative demographic and genetic consequences. Releases to larger mainland sites and predator-free areas have increased survival times, indicating higher chances for a positive translocation outcome. Moreover, translocated wild-caught and captive-sourced birds survived longer than birds from the Operation Nest Egg (ONE) programme, particularly at sites that were not predator-free. We highlight the need for genetic considerations in the planning and adaptive management of proposed and existing translocated populations. Specifically, we suggest that differences in kiwi survival, based on the type of released birds and release site’s area size and predator status, should be considered during translocation planning. The kiwi translocation review identified significant inconsistencies and often insufficiency of post-translocation monitoring. We demonstrate the utility of post-translocation monitoring methods in a recent translocation case study: a reintroduction of roroa–great spotted kiwi (A. maxima) in the Nina Valley, Lake Summer Forest Park. In 2015, eight wild-caught adults were translocated from the Hawdon Valley, Arthur’s Pass National Park, following the release of ten ONE subadults between 2011–13. We tracked the translocated kiwi by radio telemetry between 2015–17 to monitor post-release survival, dispersal, and ranging behaviour. Dispersal was highly variable among the released wild birds. The straight-line distance from the release site to the last recorded location ranged between 0.5–10.3 km. Based on the dynamic Brownian bridge movement model, seven of the wild birds survived, remained in the Nina Valley, and covered up to 1700 ha (95% utilisation distribution). Releasing the wild birds had no measurable impact on the ranging behaviour of previously released subadults. Additionally, we used occupancy modelling to analyse passive acoustic monitoring data (PAM) from the Nina and Hawdon valleys to monitor changes in distribution and growth of the translocated population and the impacts of the translocation for the source population. We analysed data from two survey years 2012–13 and 2017–18, being before-and-after the 2015 translocation. Occupancy estimates increased significantly at both study areas, despite the translocation of approximately 20% of known territorial adults (four pairs) from the Hawdon to the Nina. Moreover, at least three out of four territories, where adult birds were removed, were re-occupied by new pairs within 2.5 years. Site occupancy increased in the Nina from 0.20 (SE 0.10) to 0.72 (0.10), and in the Hawdon from 0.63 (0.10) to 0.95 (0.04). Detectability varied significantly between study areas and was influenced by the length of survey night, breeding/non-breeding season, and wind speed. The differences between the naïve and estimated occupancy values underscore the benefits of occupancy modelling for measuring response to conservation management. This study demonstrates the utility of PAM in monitoring translocation outcomes: tracking changes in occupancy and local distribution and assessing impacts on the source population following the birds’ removal for translocation.