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Title: Factors affecting the life history, abundance and distribution of the yellow-shouldered Amazon parrot (Amazona barbadensis) on Bonaire, Netherlands Antilles
Author: Williams, Samuel R.
ISNI:       0000 0004 2694 1474
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2010
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Understanding the factors that limit endangered populations is a foundation of ecological study and conservation management. Many parrot species are vulnerable to extinction, but despite their threatened status and familiarity there have been few studies of parrots in the field. Over three years I observed the life history, abundance and distribution of the yellow-shouldered Amazon parrot (Amazona barbadensis) on the island of Bonaire. Data were first compared to other A. barbadensis populations and other Amazona species, and then examined in relation to a suite of biotic and abiotic factors in order to understand the factors constraining population growth. Reproductive success was generally lower on Bonaire than in other A. barbadensis populations, but was typical of the genus. Different measures of productivity were influenced by specific factors. Female parrots laid larger clutches where the availability of food resources on two spatial scales was greater. Hatchability was low compared to other bird species, probably reflecting inbreeding depression. Brood size at fledging was lower in areas with high abundances of potential competitors and where introduced predators were present. Chick asymptotic weight was lowest in nests exposed to the weather. The distribution of A. barbadensis varied spatially and temporally across Bonaire. Parrots were more abundant in areas of mature habitat and where there were fewer potential competitors. Seasonal migrations between rural and urban areas correlated with the previous month's rainfall. A. barbadensis uses a wide range of rock and tree cavities for nesting and key cavity characteristics for nest site selection were identified. Apparently suitable, unused cavities are available in various habitat types but gaps in our knowledge of parrot nest selection make it difficult to conclusively assess nest site limitation. These findings indicate that a range of factors negatively affect A. barbadensis on Bonaire. Fortunately these issues can be resolved with conservation management strategies and a proposal for future conservation is included in this thesis.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available