A multivariate analysis of amphibian habitat determinants in north western Italy

Abstract

Abstract The distribution of Bufo bufo, Rana esculenta complex, Rana dalmatina, Hyla arborea, Triturus carnifex and Triturus vulgaris were studied in 61 ponds in NW Italy, in relation to a number of specific habitat features. Multivariate analysis identifies those habitat parameters which classify ponds into characteristic habitat groups. Several multivariate statistical tests were carried out to identify habitat features characteristic of each species and to delineate ecological factors that influence amphibian distributions and size of breeding populations. Variables scored at each pond were: extent of aquatic vegetational cover, age of the pond, terrestrial habitats occurring near the ponds, degree of human interference, surface areas, maximum depth, chemical water factors (such as pH and water hardness). The first four of these parameters influenced breeding population presence of R. dalmatina, H. arborea, T. vulgaris and T. cristatus significantly. Densities of H. arborea, R. dalmatina, B. bufo and R. esculenta were apparently unaffected by any of these parameters; these species seem to colonize available habitats almost at random.