Spatial niche of the Italian cave salamander, Speleomantes italicus (Dunn, 1923) (Plethodontidae, Amphibia) in a subterranean system of Central Italy

A study was carried out on the population structure and spatial niche of Speleomantes italicus (Dunn, 1923) in a subterranean system of 10 caves in Umbria (Italy). The studied populations revealed a peak of activity from April to July. The relative abundance of salamanders varied throughout the year and the observed frequencies of individuals differed significantly from expected, confirming a seasonal pattern of activity. Both external and internal temperatures positively influenced the abundance of salamanders inside the caves. This relationship may principally be indirect, and presumably salamander cave activity follows prey temporal distribution patterns, which in turn are also linked to temperature. The presence of salamanders was negatively affected by high levels of air moisture both outside and inside the cave. In summer, salamanders find refuge inside caves because the air moisture outside reaches values incompatible with the physiological requirements of the species. Adults showed a significant tendency to use areas inside the cave that were closer to the entrance when the external climate conditions come in the vicinity of those suitable for the species (increased external relative humidity and decreased external temperature), and the external influence on internal micro-climate is reduced. Comparisons to other Speleomantes species are also provided.