Body size of the Russet Sparrow (Passer rutilans) was investigated during the breeding seasons of 1994 to 1996, in south-eastern Hokkaido, Japan. Both male and female arrived slightly earlier in isolated forests than in shelter belts during the study. Wing lengths of males and females were significantly longer in isolated forests than those in shelter belts, but the other body size characteristics were not differ significantly. The results indicate habitat selection of the birds depended on their body constructions, in which wing length as an indicator, body size may be an important factor. Large-sized birds select the better quality habitat than birds of small size.