Ecology of the Chinese stripe-necked turtle, Ocadia sinensis (Testudines :Emydidae), in the Keelung River, northern Taiwan

An intensive ecological study of a large population of the Chinese stripe-n ecked turtle, Ocadia sinensis, was conducted in northern Taiwan from Februa ry 1995 to May 1996. Of 661 turtles captured and measured, there were 136 u nsexed juveniles, 289 males, and 233 females; the sex: ratio was significan tly male-biased. Significant sexual size dimorphism was evident. Females gr ew larger than males; mean body size of females over four years was consist ently larger than that of coeval males. X-ray photography revealed that fem ales were gravid from March to May. Clutch size averaged 12.6 and varied fr om 7 to 17. Stomach contents collected from June to October 1995 revealed s exual differences in diet: males tended to consume animal matter, whereas f emales exhibited a dietary shift from carnivory to herbivory during growth from juvenile to adult.