Population Structure and Male Melanism in the Reeves' Turtle, Chinemys reevesii

Abstract

Mark-recapture study on a population of Reeves' turtle, Chinemys reevesii, was conducted at two adjacent ponds in the southwestern part of Gifu Prefecture. A total of 111 turtles was marked during the period from 1986 to 1987, comprising 42 males, 68 females, and one young individual. It was speculated from the age structure that females lived longer on average than males. The females were larger than the males, growing to more than 200 mm in carapace length (CL), whereas the males grew to about 160 mm in CL. Melanistic individuals occurred only in males. Submelanistic males were six to nine years old and their mean CL was 140.3 mm. Melanistic males were older than six years and larger than 120 mm in CL. The mean CL of melanistic males was 149.6 mm.