Body weights and linear measurements of Hazel Grouse Bonasa bonasia
are presented based on birds shot in 1995 and 1996 in Hokkaido. Janan. During the period from July to January of the following year the average body weights (±SD) of males ranged from 369.1±29.1g (July to September) to 415.4±15.5g (December and January), and that of females from 344.3±27.6g (July to Sepember) to 418.5±3.5g (December and January), showing a significant increase in winter. The average flattened wing, tail, tarsus and culmen lengths for males were 170.2±3.9mm, 124.7±5.9mm, 36.5±1.2mm and 13.4±0.9mm, respectively. The corresponding values for females were 169.9± 2.3mm, 117.6±2.2mm, 36.7±1.0mm and 13.3±1.2mm, respectively. There was no significant difference in wing, tarsus and culmen lengths between the sexes, but the average
tail length of males was significantly longer than that of females.