Body mass changes inTrimeresurus flavoviridis (Viperidae) on Okinawa Island, Japan

Body masses of wild-caught habu,Trimeresurus flavoviridis, were measured with known error range. Habu larger than mature female size had steeper slope in length-mass regression than smaller individuals. Females outweighed males in most snout-ventlength classes and in early summer. Gravid females outweighed non-gravid ones by about 20% on the average, but the body mass ranges of the two groups overlapped. Through the body mass change in mature females, the proportion of gravid females was estimated to be about 0.5.