Multiple clutching in southern spotted turtles, Clemmys guttata

Abstract

We examined the reproductive output of spotted turtles (Clemmys guttata) from a population in South Carolina. We used radio telemetry, palpation, and x-rays to monitor the reproductive condition of females over two field seasons. We present the first evidence for multiple clutching in a wild population of spotted turtles. Of 12 females with radio transmitters that became gravid, five produced second clutches, and one produced a third clutch. Average annual clutch frequency was 1.2 per female. Clutch frequency was independent of body size. We compared reproductive output among three populations: Ontario, Pennsylvania, South Carolina. Individual clutch sizes varied with latitude. Clutch size was largest in the north (mean = 5.3 eggs), midsized in the central population (3.9), and smallest in the south (2.9). We suggest that this pattern is related to seasonality differences, which result in different selective pressures on body size of females. Total annual egg production (the sum of all clutches within a reproductive season) by gravid females did not differ between the Ontario (5.3 eggs) and South Carolina populations (4.6). These data indicate that, although individual clutch sizes differ between northern and southern spotted turtles, total annual reproductive output is consistent in these widely separated populations.