Seasonality of the bird community in the Ogawa Forest Reserve, an old-growth deciduous forest in central Japan

The bird community in the Ogawa Forest Reserve (OFR), an old-growth cool-temperate deciduous forest in central Japan, was surveyed monthly using the point count method from September 1996 to August 1997. Of the 61 bird species observed in the OFR during the study, 41 species were recorded in the survey's circular plots. Species richness was lowest (6) in January and peaked (21) in April. Total bird abundance was also lowest (25 birds/10 ha) in January and peaked (138 birds/10 ha) in April. As for the migration status, resident species such as tits (Paridae), long-tailed tits (Aegithalidae) and woodpeckers (Picidae), dominated throughout most of the year. During the breeding season (April-August), summer visitors accounted for 20 to 33.3% of species richness and 10 to 27% of abundance, but never reached a level comparable to those of resident species. In non-breeding season (October-February), winter visitors accounted for up to 27% of species richness and up to 72% of abundance. The temporary dominance of winter visitors in December is attributed to waxwing flocks, which were not recorded either January or February. An ordination using non-metric multidimensional scaling showed that the bird community varied more during the non-breeding season than during the breeding season. Compared with the seasonal patterns of bird communities in other types of forest along the migration route, a characteristic of cool-temperate deciduous forests is that they have a highly diverse avifauna during autumn, suggesting that such forests are important stopover sites for migrants.