Changes in diversity of seven anuran communities in the Ecuadorian Andes

In the Ecuadorian Andes, populations of 24 anuran species have been reported to be in the process of decline or extinction since the late 1980s. In spite of these reports, quantitative data on population trends on anuran populations in Ecuador are scarce. We compare relative abundance and species composition in surveys conducted between 1967 and 1988 (initial surveys) with surveys conducted between March 2000 and November 2003 (recent surveys) in seven anuran communities in the Andes of Ecuador. A total of 76 anuran species was registered. In 88 populations corresponding to 73 species in seven localities, 56 of them decreased and 27 increased their relative abundances. We observed significant differences in the number of species present in the initial surveys with respect to recent surveys. In six out of seven localities we registered fewer species than previously, even though capture effort was greater in recent surveys. Differences were of higher magnitude for species with aquatic larvae (34 species in initial surveys and 17 in recent surveys). Differences were not significant for species with direct development (genus Eleutherodactylus; 28 species in initial and recent surveys). We registered increases in the upper limit of the altitudinal range for six species and nine new records for six localities.