Changes in the Population Structure and Diet of the Chinese Stripe- Necked Turtle (Mauremys sinensis) Inhabiting a Disturbed River in Northern Taiwan

Abstract

The population structure and diet of the Chinese stripe-necked turtle, Mauremys (Ocadia) sinensis, were investigated in the Keelung River, northern Taiwan, following severe habitat disturbances. During a 2-yr levee construction and channel dredging project, the physical characteristics and riparian vegetation of the river were dramatically altered. Compared with results obtained prior to the disturbance, sex ratios were significantly skewed toward males, and the proportion of larger females significantly decreased both during and after project construction. Moreover, fewer small-sized juveniles were found following the construction disturbance. The diet of M. sinensis also changed, with plant materials assuming greater importance than they had prior to the disturbance. Furthermore, the mean volume of food ingested decreased both during and after the project. This tendency was more pronounced in females than males. Dietary overlap indices between the sexes during (0.591) and after (0.922) the project suggest that intraspecific food competition increased throughout the duration of the study.