与那国島におけるコウノトリＣｉｃｏｎｉａ ｂｏｙｃｉａｎａの集団越冬

Abstract

A flock of Oriental White Storks appeared in Yonaguni Island, the westernmost Japan in November 1993. The flock size at the time was eleven. The communal roost that was formed in a lowland valley with paddy field seems to have been shifted to another paddy field area during a short period in March 1994, probably due to human disturbance at the former place. Another important habitat for storks was pasture where they foraged. The flock of eleven storks were never recorded after December, but it is highly probable that the eleven birds overwintered in the island, since roosting of a single bird apart from the communal roost with ten birds was suggested for a night in February. Large flocks at the communal roost were recorded last on 19 March and thereafter one or two storks were witnessed until the summer of the year.