Northern mockingbirds (Mimus polyglottos), henceforth “mockingbirds”, are well-known for their robust operatic abilities. Mockingbird songs consist of a combination of unique vocalizations as well as mimicry of other taxa and non-biological sources. This project examines whether mockingbird songs serve as an accurate index of local avian species richness. Since mockingbirds are open-ended learners, I hypothesized that the song repertoire of a northern mockingbird is an accurate indicator of the avian species present in the mockingbird’s territory. To assess the role of local bird diversity in mockingbird songs, I conducted point counts at 15 sites selected to reflect an environment with varying degrees of urbanization. At each site, I recorded two days of birdsong. I isolated regions of audio containing mockingbird song and identified mimicked species within each song bout. For each site, I cross-referenced the mimicked species detected with the point-count data. I conducted a total of 30 point counts at 15 sites with documented mockingbird activity. Preliminary results span over 500 audio files containing mockingbird singing bouts across a rural-urban gradient and suggest a measurable overlap between species mimicked and local avian richness. Evaluating how the song of the northern mockingbird changes in response to variation in avian species richness will provide insight into the cognitive plasticity of open-ended song learners and the capabilities of mockingbird songs as a proxy for local avian diversity.