The status of forest birds in Japan was analyzed using the data of “The Project for Monitoring Ecosystems in Japan (Monitoring Sites 1000)” conducted from December 2004 to February 2008. Species richness in winter, and bird abundance and biomass in both breeding and wintering seasons, were all greater in southern regions. However, species richness in the breeding season was highest in suitable deciduous broad-leaved forest in the central region of the country and lower in northern and southern regions. In the breeding season, insectivorous species were abundant in northern regions and aerial, fly-catching species were more abundant in southern regions. During winter, ground foraging species were abundant in southern regions, whereas the proportion of tree trunk foraging species was higher in northern regions. Bird communities during the breeding season could be classified into four groups in terms of species composition, while those during winter were classified into three. Potential natural vegetation zones provided an indication of the community classification. Bird species representative of the groups were, for instance, Coal Tit Parus ater, Willow Tit P. montanus, and Eurasian Nuthatch Sitta europaea occurring in forests in the colder region and Brown-eared Bulbul Hypsipetes amaurotis, Varied Tit P. varius, and Japanese White-eye Zosterops japonicus inhabiting forests in the warmer region. Monitoring these species closely is required because their distributions and populations may change due to global warming in the future.
2011 The Ornithological Society of Japan