Double egg-deposition in the european pond turtle, emys orbicularis, from central Italy

Abstract

The reproductive condition of Emys orbicularis females (presence or absence of oviductal eggs) was studied by palpation and radiography in a coastal population of central Italy (Tuscany). Forty-nine females were recaptured at least twice during the reproductive period in 1997; 15 of them were found without eggs, 29 reproduced at least once, and 5 reproduced twice. The period of egg retention was estimated to be three to four weeks, and the time between two depositions about 34 days (n = 5). Despite the small sample of females reproducing twice, there is a significant tendency regarding a positive correlation between frequency of reproduction and female body size, within the study population. Reproductive females were bigger than females found without eggs; in addition, carapace length increased significantly in females found zero, one and two times with eggs. A comparison with preliminary data from northern populations of E. orbicularis, lead to the hypothesis that the annual clutch frequency could be negatively related to latitude, the model of this relationship should be still a matter of discussion. © 1998 Taylor & Francis Group, LLC.