Coastal and offshore areas of the eastern United States provide valuable resources for both migratory songbirds and breeding seabirds, but face some of the most drastic rates of habitat alteration and urbanization. Coastal development can result in loss of significant habitats, and in proliferation of collision hazards that can pose a grave threat to birds. Conserving birds that use these coastal and offshore areas requires better information on how coastal stopover habitats are used, what breeding populations visit these regions during migration, how birds move through these landscapes, and how development can be most sensibly and responsibly directed to minimize adverse effects. In the first chapter, I used hydrogen stable isotope analysis of feather samples to identify the likely breeding origin and describe the geographic timing of migration for Blackpoll Warblers (Setophaga striata) and Red-eyed Vireos (Vireo olivaceus) at a coastal stopover site in the Gulf of Maine, USA. In the second chapter, I used a regional-scale automated radio telemetry array to study stopover and migratory flights and migratory routes of these species at the same coastal stopover site. In the third chapter, I used the same automated radio telemetry array and bird sample to test the hypothesis that blackpolls and vireos – which differ markedly in migratory strategy, route, and diet during fall migration – differed in the degree to which they exhibited prolonged stopover in the Gulf of Maine. In chapter four I turned my attention to seabirds breeding the Gulf of Maine. I used automated VHF radio telemetry to study colony attendance patterns of Common (Sterna hirundo) and Arctic Terns (Sterna paradisaea) in the Gulf of Maine where both species are facing regional declines in productivity, and compared foraging metrics between incubation and chick rearing. Finally, Appendix A details an interdisciplinary publication co-authored with another PhD student, in which we used the tern foraging metrics to build a Markov movement model that can predict space use of Common and Arctic Terns, and estimate collision mortality under a range of spatially explicit alternative OWED development scenarios.