Animal sexual signals (e.g., songs, displays) determine who mates with whom and, thus, animals are expected to produce and prefer signals typical of their own species. This is a challenge when both signals and preferences are learned, as are bird songs, since juveniles are likely to be exposed to and could mistakenly learn the songs of other species. Juvenile birds express behavioral preferences to respond to and learn their own species' songs. When birds listen to songs, genes involved in neuro-plasticity and -activity are expressed in auditory brain regions, but we have no understanding of how species differences in these expression patterns arise. In this project, we have stimulated gene expression in the auditory brain regions of juvenile pied (Ficedula hypoleuca) and collared flycatchers (F. albicollis). We have micro-dissected out auditory brain regions and will compare transcriptomic responses in both species to playbacks of either their own or the other species. Our results will give insight into the genes underlying song discrimination and how differences arise between closely related species.