Health risks associated with the conservation of kākāpō (Strigops habroptilus) on offshore islands : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Manawatū, New Zealand
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Date
2021
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Massey University
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Abstract
New Zealand has a long history of using translocations of native fauna for conservation and offshore islands have been regarded as isolated ecosystems for conservation purposes. Maintaining the biosecurity of these islands is a fundamental part of conservation management. Island translocation has protected the endemic New Zealand parrot kākāpō (Strigops habroptilus) from becoming extinct and resulted a viable population in three offshore islands outside its historical range. However, kākāpō have been affected with novel diseases arising in the island sanctuaries. The aim of this research was to investigate the health risk for kākāpō in offshore islands, focusing on two main diseases. Exudative cloacitis is a disease of the cloaca in kākāpō from Whenua Hou for which no aetiology has been identified. An epidemiological study was conducted to identify the factors associated with the initiation of this disease in kākāpō. Results suggested that the disease is unlikely to have an infectious origin and diseased birds were not geographically clustered within Whenua Hou but reflected the kākāpō distribution within the island. Analysing the pH, moisture and ammonium content of kakapo roost materials did not show any evidence for the cause of the disease in the cloaca. Disease incidence has not been affected by the annual maximum temperature and rainfall each year.
Erysipelas, an acute infection caused by the bacteria, Erysipelothrix rhusiopathiae, emerged as a small cluster of mortality in translocated kākāpō in 2004, and has subsequently been diagnosed as a sporadic cause of death for kākāpō and other endangered New Zealand fauna. This study reported the presence of E. rhusiopathiae in different seabird species in two islands Whenua Hou and Te Hauturu-o-Toi through a targeted survey. Whole genome sequencing revealed that there was a geographic difference in genomic diversity of E. rhusiopathiae, and phylogenetic evidence suggested seabirds as a possible reservoir of the organism for endangered native land birds. An Erysipelothrix spp. phylogenetically different from E. rhusiopathiae was detected in Cook’s petrels (Pterodroma cookii) and in kākāpō indicating the diversity in the genus Erysipelothrix in these island ecosystems.
The investigations in this thesis demonstrate that while island translocations have been instrumental in conserving endangered fauna in New Zealand, this conservation strategy does expose the translocated populations to novel health risks. Disease management should be a priority in managing endangered species and these results should help to guide management actions for new health issues as they arise.
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Kakapo, Conservation, Diseases, Wildlife relocation, New Zealand