Communal roosts of birds formed on the street trees are problems in many cities, but no drastic solution has been found. Therefore, it is considered necessary to clarify the current situation of communal roosts from quantitative investigations and to accumulate knowledge of communal roosts formed on the street trees. The purpose of this study was to investigate the communal roosts on street trees of Kyoto city as an example, and to grasp the current situation. A research site was selected from places where Passer montanus and Spodiopsar cineraceus roosting in Kyoto. The survey was conducted once a week between June 13 and November 4, 2018, recording the number of roosting individuals, the time of roost initiation and completion, and roosting status. As a result, it became clear that a population roost will be formed until October. Furthermore, it was found that the population of P. montanus and S. cineraceus forming the communal roost increased during June. In addition, the initiation and completion times of roosting are close to the changes in sunset time, and it is considered that the sunset time is one of the factors affecting the roosting time. And, it was thought that there could be trees that are favored as roosts.
