Female reproductive phenology in a population of Hermann's tortoise Testudo hermanni hermanni in Corsica

摘要

We used radiography over two breeding seasons to investigate female reproductive phenology in a Corsican population of Hermann's tortoise. Wild females were kept in semi-captivity in similar conditions to the wild. The main purpose of the study was to determine the length of the breeding season for each female, the laying period, and the approximate length of the inter-clutch interval and clutch retention time. Clutches were laid only in May and June, and in both years the monthly proportions were similar. In 1998 the length of the breeding season (mean +/- SE = 44.7 +/- 3.3 days) was greater than in 1999 (33.1 +/- 2.6 days), but we found no annual differences in the date of first and second clutches. There were no differences in the inter-clutch interval between individual females or between years. Clutch retention time varied among clutches of the same year, but not between years for the same clutch order. When considering the order in which the clutches were laid, we observed that the first clutches were concentrated in May, whereas the second and third clutches were concentrated in June. In both years, only the females that laid their first clutches in May were able to lay a second or even a third clutch in June. Bigger females tended to lay first clutches earlier in the breeding season than did the smaller ones. The differences observed in the length of the breeding season between years may be explained by the annual differences in the frequency of females that produced one, two or three clutches, since we found no annual differences in the date of first and second clutches, in the inter-clutch interval or in the clutch retention time (for the same order of clutches).