The Effects of Urbanization on the Dispersal of Native Forest SongbirdsEPA Grant Number: FP916383
Title: The Effects of Urbanization on the Dispersal of Native Forest Songbirds
Investigators: Whittaker, Kara A.
Institution: University of Washington
EPA Project Officer: Packard, Benjamin H
Project Period: January 1, 2004 through December 31, 2006
Project Amount: $104,461
RFA: STAR Graduate Fellowships (2004) RFA Text | Recipients Lists
Research Category: Fellowship - Terrestrial Ecology and Ecosystems , Academic Fellowships , Ecological Indicators/Assessment/Restoration
Habitat loss and fragmentation as a result of urbanization are altering the population dynamics and community composition of songbirds in the Puget Sound Region and leading to the extirpation of species in some areas (Donnelly and Marzluff, 2004). For bird populations to remain connected after their habitat becomes isolated into separate patches, they must be able to successfully disperse between habitat remnants. The process of dispersal is essential for maintaining metapopulations (Levins, 1970), source/sink dynamics (Pulliam, 1988), and gene flow. The objectives of this research are to: (1) describe the process of bird dispersal in a heterogeneous urban landscape characterized by a pattern of fragmented forest patches; and (2) make recommendations to local policy makers, city planners, and land developers regarding the land-use and land-cover patterns that are most conducive to successful bird dispersal.
I am investigating three types of dispersal by 10 target species at 30 study sites in the Seattle metropolitan area: postfledging movements, natal dispersal, and breeding dispersal (Clobert, et al., 2001; Kenward, et al., 2001). Postfledging movements of juvenile birds are being tracked using radio telemetry for a subset of the four largest-bodied target species at a subset of fragmented and control study sites. I am measuring the distance, rate, and direction of movement with GIS to make comparisons between species and landscape characteristics, including patch quality, forest connectivity, and urban land-use intensity. Natal and breeding dispersal are being considered at multiple spatial scales: short-distance dispersal (within the Seattle metropolitan area) and long-distance dispersal (beyond the Seattle metropolitan area). For short-distance dispersal, I am estimating the relative rates of natal dispersal versus natal philopatry of juveniles and breeding dispersal versus site fidelity of adults by resighting and recapturing color-banded birds within and between study sites. These rates also will be compared to patterns of patch quality, forest connectivity, and urban land-use intensity. For long-distance dispersal, I am analyzing recovery data of banded birds of the same target species that were banded and/or recovered in western Washington (provided by the USGS Bird Banding Laboratory). My goal is to describe how long-distance dispersal movements vary in distance and direction between species, sexes, and age classes. By combining the results of each of these three methods, I will have a good understanding of the land-use and land-cover patterns that are most conducive to successful bird dispersal in urban areas.