Reproductive ecology of the painted turtle (Chrysemys picta marginata) in southwestern Quebec

Abstract

The reproductive ecology of painted turtles (Chrysemys picta marginata) was studied over 3 years (1983–1985) in southwestern Quebec. We used X-ray photography to determine clutch size, egg size, and clutch frequency in conjunction with radiotelemetry to determine when and where the eggs were being deposited. Data on nesting frequency indicated that between 40 and 80% of the 7- to 11-year-old females reproduce each year. All females > 11 years of age reproduced each year and exhibited a substantial reduction in growth compared with younger adult females. The percentage of those females that layed two clutches in a season ranged from 5 to 32%. There was no difference in the size of the first and second clutches or those produced by females only laying one clutch. The average clutch size was found to be 9.2 (range, 5–12) eggs. There was no significant relationship between clutch size and body size, between clutch size and age, or between clutch size and egg size. There was a significant positive linear relationship between egg size and body size. Age-specific fecundity increased up to 20 years of age and then decreased. When compared to studies of more southern populations of painted turtles, the major reproductive strategy for this population seems to be to produce a larger number of large eggs per clutch.