Term of Award

Summer 1989

Degree Name

Master of Science in Biology

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Department

Department of Biology

Committee Chair

Sara Neville Bennett

Committee Member 1

Michael P. Moulton

Committee Member 2

Wayne A. Krissinger

Committee Member 3

Denson Kelly McLain

Abstract

A previously undescribed community of introduced finches inhabiting 5 urban parks on the island of Oahu, Hawaii was described, and factors influencing the community structure examined.

Twelve of the 15 introduced finch species were regularly observed in the urban parks, with 4 "core" species (Passer domesticus, Carpodacus mexicanus, Paroana coronata, Lonchura oyrzivora) inhabiting all 5 parks both summer (June xx to August yy, 1988) and winter (December xx-tt, 1988). Five species (Amandava amandava, Cardinalis cardinalis, Estrilda astrild, Lonchura malacca, Lonchura punctulata) were occasionally present in some parks and/or were seasonal park users and were categorized as non-core species. The remaining 6 species were considered "rare" in the urban parks and were excluded from further analyses.

Larger parks did not have more species or more individuals per species than smaller parks. All species varied in their seasonal use of parks, with abundances (number of individuals/species) declining in winter. Estrildid species demonstrated the most seasonality in park usage, while more generalized feeders had less seasonal variation in abundance. A Spearman corrrelation of park occupancy and abundance indicated that more abundant species occupied a greater number of parks. The elapsed time a species had been on Oahu was found to be weakly correlated with both the number of parks occupied and the abundance of a species. Although grass seeds represented the most abundant resource, Mann-Whitney U tests indicated no significant association between the abundance of grass seed-feeding finches and non-grass seed feeding finches and the resource level. Spearman correlations of Levins index with species distributions and abundances indicated that more generalized species were not found in more parks and were not more abundant than more specialized species.

To test the hypothesis that competition influenced urban park finch community structure on Oahu, analyses of extinction rates versus the number of finch species present were made. Extinction rates of species were tested over 12 time periods of approximately 10 years each (120 years) for nonlinearity. Of the 4 species groupings analyzed, 2 were marginally significant and 2 were insignigicant, indicating that competition may have influenced the community structure of the finches.

Biogegraphical analyses were made to determine if the success rate of finch introductions was influenced by phylogeny, native zoogeographic region, and native range size. Results indicated that at the familial level for Oahu finches, no association existed between phylogeny and introduction success. Additional analyses of native zoogeographic region and introduction success indicated native zoogeographic region had no association with the success of finches introduced to Oahu, Hawaii. Native range size was used as an index of species ecological flexibility. No association was found with native range size and the success rate of finch introductions. Finches were compared by range size within zoogeographic regions, but no relationship was found between success rate of introduction and native range size within zoogeographic regions.

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