Bird populations were censused by the spot-mapping method in a natural deciduous broad-leaved forest at Tomakomai, southern Hokkaiso, during the breeding seasons of 1982 and 1983. During the study period 44 bird species were recorded;35 species occupied territories within the study area. The most abundant species were Ficedula narcissina, Cettia squameiceps, Phylloscopus occipitalis, Parus palustris, Parus major, Sitta europaea, and Passer rutilans. Although the total number of trees of 5 cm DBH and larger and basal area decreased from 1, 665/ha and 27.65 m²/ha respectively in 1982 to 1, 060 and 18.75 m²/ha in 1983, the species composition and the number of pairs for most birds did not differ significantly between 1982 and 1983. The diversity of the bird community, as calculated by the SHANNON-WEAVER formula, is 4.27 in 1982 and 4.44 in 1983. The results were discussed in comparison with some other bird community studies done in Hokkaido.