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Extramural Research

Grantee Research Project Results

Grantee Research Project Results

Exotic Bird Invasion Into Forests of Hawaii: Competition, Demography, and Impacts

EPA Grant Number: U915986
Title: Exotic Bird Invasion Into Forests of Hawaii: Competition, Demography, and Impacts
Investigators: Foster, Jeffrey T.
Institution: University of Illinois at Urbana-Champaign
EPA Project Officer: Graham, Karen
Project Period: January 1, 2001 through January 1, 2004
Project Amount: $93,987
RFA: STAR Graduate Fellowships (2001)
Research Category: Fellowship - Zoology , Academic Fellowships , Biology/Life Sciences



The threats posed by exotic species to biological integrity and endangered species are second only to habitat destruction. The discipline of invasion biology recently has emerged as a synthesis of concepts from population and community ecology to address these threats and will provide insight into the basic properties of biological systems. Densities of exotic birds in Hawaii often are significantly higher in nonnative than native forests. The apparent inability of exotic birds to succeed in native forest provides a unique opportunity to directly test the factors determining invasion success of exotic species. The objective of this research project is to employ basic methods of assessing the demographics of bird populations to address complex processes of invasion.


We realize that ecosystems are spatially heterogeneous and that the interplay between spatial and demographic factors may determine if an exotic species can invade. In particular, this research project addresses the possibility that demographic differences among habitats drive landscape-level patterns in species' distributions. This research project also directly tests if competition enables a community to resist invasion, thus providing a mechanism for biotic resistance. Finally, this research project addresses seed dispersal by exotic birds. Differential dispersal of plants by exotic birds will likely have a profound effect on the future composition of native and nonnative plant communities. In Hawaii, as in many areas throughout the United States, invasions by nonnative plants are among the most severe threats to the integrity of native habitats. Yet, as the primary seed dispersers (most native frugivores are extinct), exotic birds also may play a role in the maintenance of native plant species, many of which are bird dispersed.

The results of this research project should be useful in developing conservation strategies to minimize the negative impacts of exotic birds on native plants and animals.

Supplemental Keywords:

fellowship, native plants, nonnative plants, exotic bird invasion, Hawaii, exotic species, endangered species, habitat destruction.

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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