Distribution and Status of Gray-faced Buzzard Eagle Butastur indicus on the Northern Izu Islands, Japan

Abstract

Population of the Gray-faced Buzzard Eagle, Butastur indicus, a top predator of the insular food webs, were surveyed on the northern Izu Islands, central Japan. In 1993-1995 breeding seasons, the home ranges of one, three and seven breeding pairs were found on To-shima (4.2 km²), Nii-jima(22.8 km²) and Kozu-shima (18.4 km² ), respectively. No home range was found on Shikine-jima (3.7 km²), the smallest and relatively flat island. The home ranges tend to locate on the valleies of each island, and their numbers on each island increase with the area and topographic complexity.