Abstract
Shrub-grassland bird populations were censused along four 2-km transects in grasslands along the middle reaches of the Ishikari River, central Hokkaido from late April to mid-July, 2009 to know adequate period for census to get information of breeding populations. Numbers of species recorded showed significant seasonal changes during the study period. Abundance indicated by the proportions of numbers of birds counted to the maximum number of birds during the study period also showed significant seasonal changes. Based on the results obtained, adequate periods for shrub-grassland bird census are May and June. Since song activities peak in May and June, it is desirable to conduct a census at least once a month in the months.
