Trophic niche of cave populations ofSpeleomantes italicus

Abstract

This paper investigates the trophic niche of a poorly studied cave salamander, Speleomantes italicus. We examined Central Appennine hypogean populations that inhabit seven caves situated in three limestone areas in Umbria Region (Italy). Adults displayed feeding activity from May to December and the Vacuity Index analysis revealed a discontinuous trophic activity pattern throughout the year related to prey phenology. According to the qualitative analysis of the trophic spectrum, the populations in question can be defined as euryphagous, while the quantitative analysis (in terms of number and volume of preyed taxa) revealed a specialist strategy with a clear preference towards Diptera Limnobiidae. Both sexes presented similar trophic niche breadth and a high diet overlap, showing no intersexual differences. The hypogean populations of S. italicus, similarly to S. strinatii, showed a narrower trophic niche than epigeans of the same species, probably due to the limited food availability in the cave habitat.

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

“…Because in most caves the number of observed adults was low, we took in account only the caves with n.15 (AA2 and EN) for estimating the sex ratio. The salamander foraging activity observed during the same period for all the sampled caves (Vignoli et al 2006), led us to considered all the caves as suitable for salamanders and hence usable in the analyses of the spatial use, despite the low number of sampled individuals. Salamander monthly activity pattern (A) was evaluated only for Cave EN, where we observed a consistent number of individuals throughout the year.…”

“…Digital photos of the dorsal and ventral colour patterns were taken to allow individual identification (Salvidio et al 1994;Laghi et al 2005;Vignoli et al 2006). To avoid data pseudoreplication biases (Hurlbert 1984), data on recaptures were excluded from the analyses.…”

“…Inside the caves, salamanders were sampled by means of Visual Encounter Surveys (VES) (Heyer et al 1994), caught by hand and then sexed. Individuals smaller than the smallest captured male with evident mental gland (typical of reproductive males) were considered juveniles (Vignoli et al 2006). As far as the use of habitat is concerned, the elevation from the ground (H) (measured to the nearest 0.01 m as the length of the projection on ground of the specimens at the first sight) and the distance from cave entrance (E) (measured to nearest 0.01 m as a straight line from the entrance to the projection on ground of the salamander position at the first sight) for each specimen were recorded.…”

“…Annual average temperatures vary from 6uC to 11uC (Menichetti 1987) and rainfall from 900 to 1440 mm/year (1900 at high altitudes). For a detailed description of the study area and the caves that were investigated, see Vignoli et al (2006).…”

“…It is a eurizonal (80-1600 m a.s.l) and meso-hygrophylic species, usually related to forest ecosystems or derived habitats, inhabiting clefts but also caves and artificial cavities (Lanza et al 2006). Scarce information is available on the ecology of this species (Pastorelli et al 2001;Casali et al 2005;Pastorelli et al 2005;Vignoli et al 2006). In particular, only a few studies have addressed the population structure and spatial niche of S. italicus, and all these concern populations from the Northern Apennines (Pastorelli et al 2001(Pastorelli et al , 2002.…”