Dialects may signal social or population identity and increase tolerance within communities. We hypothesized that in European starling Sturnus vulgaris communal roosts, birds coming from the same breeding area, i.e. dialectal zone, might tend to stay together within the roost. Recordings were performed in the colonies, revealed in earlier studies, multiple dialects and small sectors where birds shared the same variants at the different levels. We also performed recordings in different locations within night roosts. The dialects recorded in the roosts were the same as those recorded at nest sites during the day and they were not distributed randomly within roosts: birds from the same geographical diurnal origin would gather and stay together, either because they arrived together or were attracted to their dialect. Although our results have to be confirmed by the study of identifiable individuals, we propose original lines of thought on roost structuring and on the role of song dialects.