A Report of the Ranging and Roosting Behaviors of a Breeding-failed Male of the Gray-faced Buzzard Eagle (Butastur indicus)

Abstract

In 1998 we studied the ranging and roosting behaviors of an adult male Grey-faced Buzzard in a low mountain region at Ogawa Town, central Saitama Prefecture, Japan. The male was confirmed to be breeding in early May when we started our survey, but failed in the breeding in early June (probably the late stage of incubation). The male was captured and fitted with a radio-transmitter. We radio-tracked the male from early May to late September (immediately before the migration). The home range size of the male was 0.60km² during the incubation period (May). After the breeding failure (June-July), the range size expanded to 5.03km² encompassing the whole range of the incubation period, and thereafter (August-September) it came to be 2.52km². The male did not roost at the same place on two successive days. During the incubation period the average distance between two roost sites on consecutive days was 184±106 SD m (N=3, range: 60-250m, SD=standard deviation), but thereafter increased to 1, 153±795 SD m (N=31, range: 80-2, 875m).