Abstract
In Japan there has been a marked tendency for White Wagtails Motacilla alba to expand their breeding range southward, especially along the sea coast. Only very recently the breeding of White Wagtails inland in central Honshu has become noticeable. We investigated the breeding records and breeding habitats of this species in Tochigi Prefecture, an inland prefecture in central Honshu. The breeding records were gathered through our own observations, literature, and personal communications. The breeding habitat was investigated by the line census in four different types of environment. The results obtained were as follows.
(1) All the known breeding records of White Wagtails in Tochigi Prefecture do not antedate 1976, except for one record at Kanuma in 1965. In Utsunomiya, the breeding records have increased every year since 1979.
(2) The breeding habitats of White Wagtails were the streams without gravelly areas, factory areas with narrow waterways, and town areas. In such environments, the Japanese Wagtail Motacilla grandis, a species closely related to M. alba, occurred only in low density.
(3) White Wagtails were not found in the river with gravelly areas, where Japanese Wagtails occurred in high density. In winter the two species frequented the same gravelly areas. It is suggested that in the breeding seasons Japanese Wagtails exclude White Wagtails from the habitat.
(4) The breeding season of White Wagtails was one or two months late than that of Japanese Wagtails. The difference of the time of breeding between the two species may enable the former to settle and breed near the breeding ground of the latter.
