Estimating the population size of orange-fronted parakeets (Cyanoramphus malherbi) on offshore islands of New Zealand

ABSTRACT

Determining the size of translocated populations of endemic New Zealand species is essential for assessing their management requirements; however generating estimates can be constrained by the accessibility of sites, particularly for cryptic or difficult to monitor species released on remote islands. In this study, we aimed to produce estimates of population size for three translocated populations of the critically endangered orange-fronted parakeet (Cyanoramphus malherbi), after a mean establishment period of 6.3 years. We also recorded natural history notes of the species. Using fixed-point distance sampling, we assessed the populations established on Te Kākahu-o-Tamatea / Chalky Island, Te Pākeka / Maud Island, and Oruawairua / Blumine Island. We confirmed the presence of orange-fronted parakeets on Te Kākahu-o-Tamatea / Chalky Island but could not produce density estimates due to a small number of detections. We did not detect orange-fronted parakeets on Te Pākeka / Maud Island. On Oruawairua / Blumine Island, based on 20 detections, we estimated a population of 193 ± 91 parakeets distributed through the mature forest of the 3.77 km² island. Our findings indicate that Oruawairua / Blumine Island sustains a significant population of the critically endangered orange-fronted parakeet. To assess the long-term trends of the species on offshore islands, further population assessments are needed.

KEYWORDS:

• Parrot survey
• population size
• density estimates
• distance sampling
• bird conservation

Acknowledgements

We thank our field volunteers, Luke Martin and Emma Wells for their assistance with surveys on Te Kākahu-o-Tamatea / Chalky Island and Te Pākeka / Maud Island respectively. Thanks to the New Zealand Department of Conservation, in particular to the Orange-fronted parakeet Recovery Group for granting permission to access field sites. Thanks also to the Picton Office and Te Anau Area Office of the Department of Conservation for providing the landing permits and quarantine processing necessary to conduct field work.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

Funding for our surveys was kindly provided by The Auckland Zoo Conservation Fund, the Brian Mason Scientific and Technical Trust, Canon Environmental Grants, the James Sharon Watson Conservation Trust, the Royal Forest and Bird Protection Society of New Zealand, and Massey University.