Hybrid zones are of special interest to investigate the speciation process and which processes either favour or impair reproductive isolation. In passerine, mating is largely driven by the selection of the sexual partner by females which assess acoustic and visual signals. Song is a particularly interesting in this regard as this signal is learnt. This implies that there is a cultural component to its transmission, a substantial deviation from the genetic mechanisms of information transmission. This project investigated the hybrid zone between two warblers Hippolais icterina and H. polyglotta. The zone is moving which resulted, as expected, in an asymmetrical pattern of introgression, the expanding species being the most introgressed. In sympatry these warblers exhibited bilateral song convergence though. Genetic analyses could not fully account for the geographical song variation pattern, suggesting that song learning may either limit the opportunity for reproductive isolation in sympatry. Song convergence seems to enhance social interactions between both warblers, and ultimately contribute to the receding of H. icterina. Consistently, distribution modelling suggested that the interactions between theses warblers limited their breeding ranges.