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Effects of Local and Regional Environmental Variation on Avian Community Dynamics and Reproductive Success in a Shredded LandscapeEPA Grant Number: U915810
Title: Effects of Local and Regional Environmental Variation on Avian Community Dynamics and Reproductive Success in a Shredded Landscape
Investigators: Truan, Melanie L.
Institution: University of California - Davis
EPA Project Officer: Broadway, Virginia
Project Period: August 1, 2000 through August 1, 2003
Project Amount: $80,437
RFA: STAR Graduate Fellowships (2000) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Ecology and Ecosystems
The objective of this research project is to experimentally investigate the community dynamics and reproductive success of selected avifauna in a shredded lowland riparian system. While habitat shredding appears to be common in developed areas, the unique patterns and processes associated with this phenomenon have not been well studied. A more detailed study combining demographic response variables to site-specific local and landscape factors will provide further model refinement and insight into the mechanisms underlying observed patterns.
This study will quantify the distribution and abundance of shred avifauna at fixed, randomized plots along a longitudinal riparian gradient, correlating these population parameters with local site variables using fixed-radius avian point counts, vegetation releve surveys, and circular-plot habitat analysis. To analyze the effects of landscape variables on population and demographic parameters, landscape elements will be quantified for each study plot using a geographic information system (GIS). To obtain detailed measurements of survivorship and reproductive success, artificial nest boxes will be installed on each plot to provide nesting sites for selected cavity nesting species. An analysis of the distribution, colonization rates, and fitness indices for these easily studied species will provide information on shred source-sink dynamics, competitive interactions, site fidelity, and breeding responses to local and regional environmental variables. Avian population data will be analyzed using life history tables and descriptive statistics. Avian habitat relationships will be analyzed by means of multivariate statistical methods such as multiple logistic regression and canonical correspondence analysis. Landscape relationships will be analyzed using Arc/INFO and spatial statistics programs (FRAGSTATS*ARC).
Several hypotheses have been proposed: (1) community patterns (i.e., species replacements and/or shifts) will occur along a longitudinal gradient; (2) patterns for native species will differ from those for nonnative or human-associated species; (3) patterns for resident species will differ from those for migratory species; (4) nest-site limitation and competition with nonnative species at disturbed sites will influence the distribution, abundance, and reproductive success of cavity-nesting birds; (5) colonization rates of newly provisioned nest sites will be inversely related to distance from cavity-nesting bird source populations; (6) significant discontinuities in the colonization gradient and/or site-specific declines in overall fitness will be a result of overriding local or regional factors; and (7) regional or landscape variables will explain significantly more of the between-site variation than will local site variables.