TROPICAL AMPHIBIAN MONITORING - A COMPARISON OF METHODS FOR DETECTINGINTER-SITE VARIATION IN SPECIES COMPOSITION

Several methods have been proposed recently as standards for sampling and monitoring amphibians. This study sought to (1) compare several sa mpling methods during the establishment of a monitoring program and (2 ) describe differences in species composition among the study sites. W e investigated whether observed differences among sites depended on sa mpling method. The study was performed at the Jatun Sacha Biological S tation in the Upper Amazon Basin in Ecuador. We established seven site s in primary forest and sampled amphibians four times over a 5-mo peri od using transects searched during the day and night, artificial cover stations, and artificial ponds. Significantly more species were found during nocturnal searches of transects than with the other methods. I n cluster analysis of species occurrences, both diurnal and nocturnal transect searches identified one floodplain site as being distinct fro m the rest. Sites appear most similar when artificial ponds were consi dered and consistently less similar in data from nocturnally searched transects. Data from both types of transect and from artificial cover indicated that one site in the reserve's interior was particularly ric h in species of Eleutherodactylus. Additionally, nocturnal transects d etected increased species richness of hylid frogs at the two floodplai n sites. This is consistent with the aquatic mode of reproduction of h ylid frogs. Higher species richness of Eleutherodactylus is characteri stic of drier terra firme forest with low disturbance. These trends ar e most dear in data from nocturnally searched transects.