Habitat Loss and the Decline of Grey-faced Buzzards (Butastur indicus) in Tokyo, Japan

Abstract

The occurrence of Grey-faced Buzzard (Butastur indicus) in central Japan was studied in the 1970s and 1990s. There was a significant decline in the number of Grey-faced Buzzards sighted; from 28 survey squares in the 1970s to zero in the 1990s. In the Tokyo areas, the amount of edge between forests and paddy fields, which was probably an important habitat for the buzzard, was markedly decreased from 1.1 ± 1.5 km in the 1970s to 0.3 ± 0.6 km in the 1990s. The decline of Grey-faced Buzzards breeding in the Tokyo region probably was caused by the habitat loss resulting from abandonment or development of traditional paddy fields (yatoda). These human modifications probably reduced populations of suitable prey.