Date of Award

Summer 2015

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Biology - (Ph.D.)

Department

Federated Department of Biological Sciences

First Advisor

Claus Holzapfel

Second Advisor

Daniel E. Bunker

Third Advisor

Frank Gallagher

Fourth Advisor

Peddrick Weis

Fifth Advisor

Paige S. Warren

Abstract

Urban expansion is an increasing threat to native bird populations. Consequently, maintaining and developing safe urban habitat space is necessary for conservation. Birds living in, or migrating through, urban areas utilize a variety of managed green-spaces such as parks, gardens, college campuses, and cemeteries. In addition to managed habitats, birds may use abandoned property that has been reclaimed by vegetation and associated spontaneous, biological communities. Such urban habitats may provide valuable resources for birds and other wildlife; however, these sites often contain high densities of non-native plants and can be polluted, potentially imparting a greater risk than benefit to the species they attract. The objective of this dissertation is to investigate variables in the urban environment that can be attractive to birds, while at the same time pose risks. To accomplish this objective, three topics are investigated (1) seasonal variation in bird community composition in urban versus non-urban areas quantified from citizen science data, (2) avian use of native and non-native fleshy fruits and fruit availability in urban habitats and (3) the trophic transfer of heavy metal contaminants across the avian food chain in an urban brownfield. Results show that, while urban habitats may have similar communities to suburban habitats, variation in community composition within habitats is greater in cities compared to neighborhoods that are more residential. Unmanaged spontaneously vegetated urban habitats are particularly attractive to native and reduce densities of non-native bird species. However, such habitats have high densities of low-quality bird-dispersed fruits. In moderately polluted habitats, heavy metals are biotransferred from the soil to fruits, arthropods and birds, but no consistent pattern of biomagnification is present across trophic levels and concentrations for most taxa are relatively low. The results of this investigation have broad implications for the management and restoration of urban bird habitats and will contribute to the conservation of native birds in an urbanizing world.

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