Abstract
Tiritiri Matangi Island in the Hauraki Gulf region of Auckland is an open sanctuary with a reintroduced population of kakariki (red crowned parakeets, Cyanoramphus novaezelandiae). These birds originally came from captivity in the 1970's. For the past decade, there have been increasing reports of feather loss in this species on the island. In 2008, beak and feather disease virus (BFDV) was detected nearby on Hauturu island, and therefore it was suspected the feather loss might have been due to a spread of this pathogen. However, a 2-year study into health and disease of red crowned parakeets on Tiritiri Matangi has revealed a different source of the clinical signs. During four cross sectional studies from 2011-12, feather loss increased from 8% (95%CI:2.3%-18.8%) up to 52% (95%(1:38.6%-65.2%) of the population. Skin biopsies from all birds in the second year of the study found a skin mite associated with thickening of the skin (acanthosis) and excessive keratin production (hyperkeratosis). Mites were also found in asymptomatic birds, suggesting a subclinical or carrier status. Whole mites were cleared in Hoyer's medium, with larval and female forms of Procnemidocoptes jansseni identified. This mite has only been formerly described in a lovebird from Zambia (Fain 1966), raising questions as to how it came to be present in wild kakariki in New Zealand. Another skin mite Hemimyialges macdonaldi, also reported to cause mange, was found in low numbers from skin as well as on hippoboscid flies removed from several birds. The relationship between the cosmopolitan H.macdonaldi, the dominant mite P.jansseni, and the clinical signs of mange requires further investigation.
New Zealand is host to a unique avifauna, which has been significantly affected by the combined impacts of habitat modification and introduced mammalian predators. Many now thrive only on offshore islands or predator-free mainland sanctuaries, with ongoing conservation efforts reliant on re-introductions and translocations between these sites. These assisted movements, which may include periods of captive management, introduce specific biosecurity risks and potential for artificial spread of pathogens and parasites. Historically these activities took place in the absence of extensive or strategic disease screening, or prior to our current understanding of, or capacity to detect, key diseases. Results from this study will feed into captive and wild management of kakariki, specifically identifying new risks for translocations and re-introduction programs. The study also highlights the importance of epidemiological approaches to studying disease syndromes in wild populations.