Monitoraggio a Lungo Termine Del Geotritone Speleomantes Strinatii Nella Stazione Biospeleologica DI San Bartolomeo DI Savignone (Ge)

The Biospelogical Station of San Bartolomeo di Savignone is located in the Scrivia Valley (north-western Italy). This horizontal tunnel, measuring about 40 m, was excavated in marlstones during World War II, when it was used as an air-raid shelter. This cavity was naturally colonized by a population of the cave salamander Speleomantes strinatii that shows a seasonal pattern of activity, with a summer peak in July. Since 1990, salamanders active on the cave walls are counted and from 1996 the absolute population size is estimated by means of a temporary removal experiment, in which salamanders are captured in three occasions, stored in terraria and released at the end of the experiment. A clear relationship between the estimated population size and the simple salamander count is observed; this latter could be considered an appropriate index of the salamander abundance. Overall, the population size remained constant over the study period, although it showed a certain degree of variability (coefficient of variation CV = 0.29). Moreover, a weak tendency to periodical fluctuations is observed. The demographic population structure (sex ratio and recruitment) appear constant, suggesting that the population is fluctuating near the environmental carrying capaci