The line transect censuses within the range of 25m on both sides of six routes were carried out in two forests in Tanagawa, Osaka Prefecture, in 1984. One is the Environmental Green Area of Tanagawa II Power Station, which composed mainly of plantation and uncut natural forest leftover patchily. The other is the secondary natural forest adjacently near by the station. A total of 42 species (9 orders 24 families) of birds were observed. There was no difference observed in the species composition between Green Area and natural forest. But in Green Area, more numbers of species were observed in the leftover forest, and only a few species occurred in the plantation forest. While so many species of birds live in natural and the leftover forest, no special species live in the plantation forest, it is considered that avifauna is extending into the plantation from natural forests. Large-sized, groundpecking species (Columba livia, Turdus pallidus and T. naumanni) were observed abundantly in the plantation forest. This may be due to the less coverage of the forest floor.