Location of Winter Roost and Foraging Area of Grey Starling Sturnus cineraceus in the Kanto Plain, Central Honshu, Japan-Comparison with the Data Collected 40 Years Ago

Abstract

The location of winter roosts and foraging areas of the Grey Starling Sturnus cineraceus were studied in Kanto Plain, central Honshu, Japan from October 2002 to February 2003, and compared with earlier studies in the same area by Kuroda (1955, 1956, 1962). The present study located 37 winter roosts and categorized them into two types: "large roosts", occupied by 4,000 or more individuals and "small roosts", occupied by 1,000 or fewer individuals. Individuals departing from large roosts flew to more distant foraging grounds than those departing from small roosts. For the Shinhama roost, categorized as a large roost, the number of assembling individuals and their foraging area were almost the same as those observed by Kuroda between 1953 and 1962. However, a comparison between the results of the present study for the Saitama roost, categorized as a large roost, and those of Kuroda, revealed that the number of assembling individuals had decreased considerably over the four decades interim period, and that their foraging areas had also changed. Recent studies of the Grey Starling have documented the existence of fewer roost sites with larger numbers of assembling individuals in summer, and of numerous interspersed roosts with smaller numbers of individuals in winter. In the present study, however, both large roosts and small roosts were present in the study area in winter.