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    Habitat use by Tasman parakeets (Cyanoramphus cookii) and Crimson rosellas (Platycercus elegans) on Norfolk Island, South Pacific : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology, Massey University, New Zealand
    (Massey University, 2019) Simmonds, Serena Analeia
    Islands harbour a disproportionate amount of threatened vertebrate species and remain the focus of intense conservation research and management. Two important components of the ecological restoration of islands include revegetation and control of introduced animal species. The Tasman parakeet (Cyanoramphus cookii) endemic to Norfolk Island, is one of the rarest bird species in the South Pacific, with a long history of assisted conservation in particular during the breeding cycle. An introduced parrot, the crimson rosella (Platycercus elegans), is thought to compete strongly with Tasman parakeets for nesting and feeding resources, however, the degree of competition for feeding resources has not been quantified. No study has aimed at understanding the selection of available habitats by Tasman parakeets and crimson rosellas, or the relevance of restored vegetation patches for these species for foraging activities. In order to provide information to better manage a growing population of the Tasman parakeet within the Norfolk Island National Park, it is important to understand patterns of habitat use and key resources, as well as the degree of competition with the introduced crimson rosella. I studied the habitat use of Tasman parakeets and crimson rosellas during two seasons, autumn and spring 2017 by surveying 986 vegetation plots. I encountered a total of 80 woody plant species occurring on nine habitat types. The highest plant species richness was in forest edges (70 species), followed by remnant hardwood forest (43 species). The lowest plant species richness was on regenerating vegetation patches (26 species). Tasman parakeets and crimson rosellas used these habitats differently. In autumn and spring, Tasman parakeets preferred remnant hardwood forests (Manly Selectivity Index autumn: 0.50; Chi square 6.86, P < 0.001, n = 35; Manly Selectivity Index Spring: 0.32; Chi square 6.86, P < 0.001, n = 55). Crimson rosellas preferred forest edge in autumn (Manly Selectivity Index Autumn: 0.34; Chi square 24.51, P < 0.001, n = 69) and remnant hardwood in spring (Manly Selectivity Index Spring: 0.28; Chi square 4.56, P < 0.001, n = 130). In terms of feeding species, Tasman parakeets and Crimson rosellas exhibited a high degree of overlap in only one food type: ake ake (Dodonea viscosa) seeds and fruits. Opportunistic observations during summer, revealed a similar degree of overlap for consumption of seeds and pulp of red guava (Psidium cattleianum), although habitat preferences for summer or winter were not quantified in this study. I did not register a single instance of aggressive interactions between Tasman parakeets and crimson rosellas after nearly 300 hours of field observations. My results indicate that Tasman parakeets and crimson rosellas used the available habitats in the Norfolk Island National Park differently. In terms of foraging resources, Tasman parakeets and crimson rosellas do not appear to overlap greatly in food types or feeding species during autumn and spring. Future research should focus on the patterns of habitat use during summer and winter and the degree of competition for feeding resources during these seasons as well. While there has been evidence (prior to this research) of intense competition for nesting cavities between Tasman parakeets and crimson rosellas, my research reveals little inter-seasonal overlap in habitat use and feeding resource. From a management perspective, control of crimson rosellas in an around nest cavities of Tasman parakeets should be favoured over control on foraging areas. Nevertheless, crimson rosellas outnumber Tasman parakeets 3:1, and therefore my results need to be interpreted with caution as it is unclear whether foraging and habitat use patterns consistent with my research would be encountered in the future, as numbers of Tasman parakeets continue to increase.
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    Estimating the population size of two critically endangered South Pacific parakeets : the Tasman Parakeet and Malherbe's Parakeet : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology, Massey University, New Zealand
    (Massey University, 2018) Skirrow, Michael John Adam
    The Cyanoramphus parakeets are a cryptically coloured group of birds that are distributed across the islands of the South Pacific region. Due to their restricted range and island distributions, species belonging to this genus are considered vulnerable to extinction. However, the extent to which these parrot species are threatened is difficult to determine due to an absence of accurate and reliable population estimates. This research aims to contribute to the conservation of two critically endangered Cyanoramphus parakeets by evaluating the survey methods currently used to estimate population densities. This thesis details the precision and efficiency of distance sampling methods used for monitoring low density parrot populations on small islands. Specifically, examining the annual variation in population size for the critically endangered Tasman Parakeet (Cyanoramphus cookii) and their introduced competitor, the Crimson Rosella (Platycercus elegans), to evaluate the effectiveness of conservation management and species control on Norfolk Island. In addition, the size of three translocated populations of the critically endangered Malherbe’s Parakeet (Cyanoramphus malherbi) were examined to identify if this endemic New Zealand parrot requires further management. Of the distance sampling methods used to monitor parrots, the fixed point survey method was the most suitable method for surveying Tasman Parakeets. This method yielded the highest number of parakeet detections per survey and offered the greatest count precision of the methods examined. On Norfolk Island, the Tasman Parakeet population increased by 126% over four years of intense predator management and nest provisioning. In comparison, the Crimson Rosella population remained stable, despite regular culling to control the population which competes with the Tasman Parakeet. In New Zealand, Malherbe’s Parakeets were detected with varying degrees of success. On Maud Island, no parakeets were detected; however, they were detected on both Blumine Island and Chalky Island. On Blumine Island, the Malherbe’s Parakeet population was moderately abundant, consisting of 202 ± 67 individuals distributed through the mature forest. In comparison, the Chalky Island population of Malherbe’s Parakeet was less extensive and consisted of 84 ± 58 parakeets. This research illustrates the importance of regularly monitoring the size of threatened parrot populations for conservation.
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    Foraging ecology of the world's only population of the critically endangered Tasman parakeet (Cyanoramphus cookii), on Norfolk Island : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology at Massey University, Auckland, New Zealand
    (Massey University, 2016) Waldmann, Amy
    I studied the foraging ecology of the world’s only population of the critically endangered Tasman parakeet (Cyanoramphus cookii) on Norfolk Island, from July 2013 to March 2015. I characterised, for the first time in nearly 30 years of management, the diversity of foods consumed and seasonal trends in foraging heights and foraging group sizes. In addition to field observations, I also collated available information on the feeding biology of the genus Cyanoramphus, to understand the diversity of species and food types consumed by Tasman parakeets and their closest living relatives as a function of bill morphology. I discuss my findings in the context of the conservation of the Tasman parakeet, specifically the impending translocation of the species to Phillip Island. I demonstrate that Tasman parakeets have a broad and flexible diet that includes seeds, fruits, flowers, pollen, sori, sprout rhizomes and bark of 30 native and introduced plant species found within Norfolk Island National Park. Dry seeds (predominantly Araucaria heterophylla) are consumed most frequently during autumn (81% of diet), over a foraging area of ca. 90 hectares, at 6.94 m above the ground. During winter, consumption of dry seeds remains high (61%) however over less than half the foraging area of autumn (46 hectares). More importantly, foraging height during winter is significantly lower than any other season, at 2.16 m. Though overall 18% of all foraging registered occurs at ground level, the highest frequency occurs during winter (55.4%). I argue that this seasonal shift in foraging area and height has important consequences for the management of Tasman parakeets. In particular foraging close to the ground within a small area makes the world’s only population of Tasman parakeets highly vulnerable to predation by introduced cats, thus intensification of cat control during this period is crucial for safeguarding this species in situ.