Amphibian diversity and abundance in Laguna San Rafael National Park (XI Region, Chile)

Abstract

The fauna of vertebrates of Chile is affected by serious conservation problems. The amphibians, with their high endemism degree, are part o f the most vulnerable groups. Amphibian surveys were carried out between 23 January - 9 February 1999 at sites on the Eastern, Southern and Western shores of Laguna San Rafael. The time spent surveying at each site ranged from 4-6 days. The sites were Glaciar (Eastern shore), San Quentin (Southern shore) and the Canal (Western shore). Five standard surveying methods were used: visual encounter surveys (VES), refugia searches, pitfall trapping, aural surveys and bottle trapping. Surveys were conducted in both terrestrial and aquatic habitats. Overall, VES and daytime refugia searches were the most productive survey methods. A total o f six anuran species were captured: Batrachyla aniartandica, Batrachyla taeniata, Batrachyla nibaldoi, Hylorina sylvatica, Eusophus calcaratus and Bufo variegatus. Species assemblage and relative abundance varied among sites: the Canal was the most species rich site, with a total of five species found. Species also differed in their distribution: B. aniartandica, B. taeniata and E. calcaratus were all widespread, occurring at all three sites; B. nibaldoi was found at two of the sites, and H, sylvatica and B. variegatus were each found at one site. Batrachyla nibaldoi is a recently described species and had not previously been recorded as occurring within Laguna San Rafael National Park (LSRNP). The species differed in abundance between habitats; B. taeniata and B. nibaldoi were plentiful in scrub habitat; B. variegatus was associated with peat-bogs; while B. antartandica and E. calcaratus preferred the forest. It is difficult to reach conclusions about H. sylvatica, as few individuals were captured. The capture of more than 300 individuals over nine survey days, including a species that was not previously known to occur in the park, suggests that LSRNP has considerable potential as an amphibian habitat.