Riparian systems support among the highest levels of avian species diversity of any habitat in the western United States. These habitats are highly sensitive to human development and have been severely degraded historically. I analyzed the changes over thirty-five years in a riparian bird community inside a biological preserve, which was protected over that time period. I examined effects on riparian bird diversity of habitat level changes in vegetation, adjoining land-cover, and watershed-scale human development outside the preserve along with changes in climate. Avian diversity declined significantly over thirty-five years, especially among Neotropical migrants and other human-sensitive species. While detectable changes in average January temperature did occur, land-use change on a regional and watershed level explained most of the change in diversity and abundance. In general, the species assemblage and abundances shifted to a more human-tolerant set of bird species. This temporal pattern of bird changes in the preserve occurred despite increased riparian area and increased vegetation structural complexity within the preserve, indicating the importance of watershed-scale changes on riparian bird communities. My research suggests an increased need for riparian habitat protection, judicious planning of human development along sensitive stream corridors, and particularly buffer areas around riparian and reserve habitats.