Population characteristics and egg production of the yellow-margined box turtle, Cuora flavomarginata flavomarginata, in northern Taiwan

From May 1996 to September 1997, we investigated population and reproductiv e characteristics of Cuora flavomarginata flavomarginata in the Feitsui Res ervoir Protected Area, northern Taiwan. Of 288 turtles captured, 174 were f emales, 95 were males, and 19 were unsexed juveniles. The overall and adult sex ratios were significantly biased toward females. Whether by baited tra p or by hand, the capture frequency was significantly female-biased. The po pulation at Feitsui was mainly composed of adult individuals (78.1%). The a verage body size of adult females was larger than that of adult males. Radi ographing revealed that females were gravid from mid-April through mid-lull : with the highest percentage in May. Periodic radiographing of radio-tagge d. females suggested that C. f. flavomarginata laid one or two clutches bet ween early May and mid-July. Carapace length of gravid females ranged from 138.0-174.8 mm (mean = 155.1). Clutch size varied from 1-3 and averaged 1.6 Egg size was positively correlated with female body size, but clutch size and annual clutch frequency were not. Turtles in the larger size classes (1 55.0-169.9 mm carapace length) were more likely to be found with shelled eg gs than the smaller-sized turtles. Larger females were also more likely to lay eggs in both of die consecutive nesting seasons. We identified seven tu rtles that reproduced in both years.