We are assembling a first-arrival database for Ruby-throated Hummingbird, Barn Swallow, Purple Martin, Baltimore Oriole, and Chimney Swift in the Eastern United States. Historical records from the North American Bird Phenology Program at Patuxent Wildlife Research Center and recent citizen science data are being matched with appropriate weather, population trend, and human influence data. Our objectives are to better understand why some species are arriving earlier than in previous time periods and others are not; and to examine spatial trends in species' responses.