Abstract
Forest bird surveys were conducted across Japan in the breeding seasons of 1994 and 1999. From the data obtained we calculated an interspecific similarity index of bird assemblage based on the presence and absence of species. The analysis revealed that birds were classified into four distinctive groups according to their sympatry. Group A consisted of 16 species, such as Garrulus glandarius , Parus ater , Troglodytes troglodytes , P. montanus , Sitta europaea and Luscinia cyanen . Group B was composed of eight species including Hypsipetes amaurotis and Zosterops japonica . Group C was comprised of three species, namely Hirundo rustica , Passer montanus and Sturnus cinera . Group D was made up of two species (Phasianus colchicus and Anas poecilorhyncha ), which were relatively uncommon in forest habitats. A similarity index ( φ ) was negative between Group A and Groups B or C, showing the bird species of the three groups are allopatric. Correlations between the MDS scores of 1994 and 1999 suggests that bird communities in the breeding season are stable over a period of a few years. Nationwide monitoring should be continued to detect the possible changes in bird communities in the national as well as regional levels so as to serve conservation aims.
