Population Structure, Growth, and Age Estimation of Spotted Turtles, Clemmys guttata, Near their Northern Limit: an 18-Year Follow-up

Abstract

Mark-recapture and radio telemetry data were collected from 1999-2001 on a population of Spotted Turtles, Clemmys guttata, near their northern limit in Ontario, Canada, and compared with a similar study conducted from 1983-1986. In 1999-2001, 32 Spotted Turtles were caught, 27 of which were adults. Females outnumbered males 3.5:1. The carapace length (CL) of adult males (108.5 ± 5.7 mm) and adult females (106.4 ± 6.0 mm) did not differ significantly. A minimum of 22% of juveniles and 40% of adults marked in 1983-1984 were still alive in 1999-2001. Adult population size was estimated to be 45 (95% confidence interval: 34-78). The average size of individual adults marked in 1983 (105.6 + 6.0 mm CL) and recaptured during 1999-2001 (106.3 + 5.9 mm CL) did not differ significantly. There was also no signficant difference in the number of growth lines on adults caught in 1983 (12.9 ± 2.0) and 1999 (14.0 ± 2.3). Based on the number of growth lines in 1983, these turtles averaged a minimum of 28.9 years in 1999, but actual ages are likely greater. Summer range length averaged 233 m (range: 200-275 m), while total range length averaged 327 m (range: 275-375 m).