Estimating abundance and biomass of a Speleomantes strinatii (Caudata, Plethodontidae) population by temporary removal sampling

Abstract

A rock-face population of the European plethodontid Speleomantes strinatii (Aellen, 1958) was studied along a small Apennine stream, in northwest Italy. Three temporary removal samples were taken in October, from 1993 to 1996, to estimate population structure, abundance and biomass. Body-size polymodal frequency distributions were resolved into separate components (i.e., estimated age classes) using the log-differences method. Each year's sample was composed of two juvenile age classes plus a mixed component in which large immature individuals and sexually mature salamanders were present. The analysis of removal data showed that capture probabilities were homogeneous within each annual sampling and were similar between juveniles and adults (mean values being 0.33 and 0.26, respectively). The population density varied between 0.6 and 1.0 individuals/m2 of rock face (average 0.8) and biomass, expressed as wet weight, between 0.98 and 1.54 g/m2 (average 1.25 g/m2). Temporary removal sampling was effective in providing autoecological data on European plethodontid salamanders living in such relatively complex microhabitats as vertical rock faces. Moreover, the results suggest that temporary removal methods can be a useful tool in monitoring amphibian long-term population changes.