Distribution and Ecology of the Alpine Newt Ichthyosaura alpestris (Laurenti, 1768) (Amphibia: Salamandridae) in Bulgaria

摘要

The Alpine newt khthvosaura alpestris is a glacial relict in Bulgaria, occurring only in several mountainous regions. Results of a long-term herpetological survey in Bulgaria are presented, including from sampling specifically targeting the aquatic phase of I. alpestris. The known ranges of its vertical and geographical distribution are now expanded - it occurs autochthonously in seven mountains (in 42 10 x10 km UTM squares, 22 of which previously unreported). We detected it for the first time in two mountains: Pirin and Karvav Karnak. However, several potentially suitable mountains remain under-sampled. A Maxent model with strong predictive power (test AUC = 0.988) based on 10 uncorrelated variables revealed that about 5% of the territory of the country are potentially suitable as habitats for this species. Elevation is the best predictor in the model, followed by slope, while precipitation seasonality and the potential evapotranspiration signify the importance of the presence of (seasonal) water bodies. khthyosaura alpestris seemingly prefers to breed in natural and semi-natural shallow water bodies with muddy bottom, grassy banks, limited reed/buhush, without fish, near or in forested habitats. The registered relative abundances (0.002-1.183 ind./trap-hour), the estimated instantaneous population densities (0.2-7.1 ind./m(2)) and the sex ratios (from 0.25 male : 1 female to 7.29: 1) vary widely among and within mountains.