Habitat Factors that Influence Oviposition Sites in Ecuadorian Glass Frogs

Abstract

The numbers of amphibians are decreasing all over the globe, particularly in high elevation areas of the Andes. Glass frogs have been studied in tropical regions, but very little is known about the species in Ecuador. The objective of my study was to determine if habitat factors influence the selection of oviposition (egg laying) sites in Ecuadorian glass frogs in the Cordillera Oriental of the Andes Mountains, at the Yanayacu Biological Station. Two and a half km of one stream were selected as the study area because its bank vegetation and stream characteristics varied throughout its length. The stream was divided into four sections each about 300 meters long, and each night one section was searched for egg masses and adults. Egg masses of Cochranella wileyi were most abundant and were used for statistical analysis. Several habitat factors were examined that were thought to possibly have an effect on oviposition choice. Five factors were found to be positively associated with the location of egg masses: the number of ferns along the margin of the stream, the number of ferns overhanging the stream, canopy cover, and the amount of riffle area in the stream. The amount of grass along the stream margin was negatively associated with oviposition sites. Together, these results suggest that high gradient streams with canopy cover and a dense fem understory are necessary for breeding activity in this species.