Exploring Raptor Migration Using Stable Isotope Analysis: The Northern Goshawk in Western North America

This thesis consists of two chapters describing my study of Northern Goshawk (goshawk; Accipiter gentilis) migration in western North America. My research objectives were to (1) characterize inter- and intra-individual variation in the stable hydrogen isotope composition of goshawk feathers and (2) use the analysis of stable isotopes in feathers to describe the migration patterns of goshawks in western North America. My research had two major field components: breeding season sample collection and migration sample collection. I conducted breeding season work during the summer of 2002 and 2003 at goshawk nests throughout the Pacific Northwest; migration work occurred during the fall of 2002 and 2003 at the Idaho Bird Observatory. Additionally, many agencies and individuals contributed breeding season samples (see Acknowledgments), and Hawk Watch International (HWI) contributed migration samples from four additional migration monitoring stations (MMSs) in the western United States. Information contained in this thesis should be of particular interest to those applying stable isotopes to studies of avian movement and/or migration and to biologists involved with research, management, and conservation of raptors, especially goshawks