One of the most intriguing features of songbirds is their immense song diversity. We aim to examine the origins and stability of song diversity using an evolutionary approach. Birdsong is a form of culture; birds can learn song components from the songs of parents and neighbours. These cultural units are known as memes and behave like genes. How rapidly do memes change and where do they come from? When do young birds learn memes? Bird song dialects have proven to be excellent models for testing cultural evolution theory. Nonetheless, song has evolved due to a range of influences. The New Zealand bellbird meta-population provides a meta-population model that will enable us to quantify genetic and cultural contributions to song diversity. For bellbirds, both sexes sing complex independent song. Within a bellbird population males and females share genetic history and the same environment but we hypothesise that memes are transferred culturally through learning intra-sexually. Bellbird females disperse between populations more frequently than males, thus, we predict that the sexes have independently evolving song diversity. This provides us with a unique opportunity to understand the dynamics of avian cultural change, how dispersal influences song diversity, and how song dialects evolve.