Nesting locations of gray-faced buzzard eagles were studied in two areas of about 348 in Tochigi prefecture. Their food items were also monitored. From the nesting data, a multiple regression model was constructed to predict the number of nesting locations within a 2x2 mesh grid from several environmental factors such as vegetation and human population size. The resulted model could explain about 70% of the variation in the number of nests (r2×0.71). Factors used in the model were length of forest edge facing paddy fields in a mesh grid and in surrounding eight meshes grids (positive factor), and population (negative factor). In the study area gray-faced buzzard eagles were feeding mainly on frogs, and the birds were observed to perch on the tree top in the forest-paddy field edge waiting for frogs to appear. The preference on forest-paddy field edge shown by the model might reflect the importance of such habitat as the species' hunting area. In our study area, the gray-faced buzzard eagles were especially abundant in continuous 'Yatsu' area, a landscape in which a low tableland is eroded by rivers to create a fractal shaped network of valleys. Our results, along with other published data, indicate that the Yatsu landscape is an important breeding habitat for this species.
2005 by Japanese Institute of Landscape Architecture