Use of Native Forest and Eucalyptus Plantations by Eleutherodactylus Frogs

Abstract

We examined population densities, movements, and habitat use of common coqui (Eleutherodactylus coqui), the most common and widespread species of frog in Puerto Rico, in native forest and eucalyptus plantations in 2 forest reserves of the Cordillera Central between July 1997 and June 1998. We established 4 grids of bamboo retreat sites on stands of native forest and eucalyptus plantations in each reserve. We established sampling points within trapping grids to quantify vegetation and determine habitat use. Sampling was conducted during the wet and dry seasons. We used mark-recapture for population estimation. Population estimates and maximum distances moved were determined using program CAPTURE. During the dry season, common coqui population densities were similar in 3 of the 4 study grids, but 1 eucalyptus site had significantly lower densities. We found no differences in adult frog density among study sites during the wet season. Horizontal movements differed between forests, albeit not significantly. Our results indicate that plant species richness did not affect common coqui density. Coqui density was influenced more by vegetation structure than by plant species composition. Five habitat variables (midstory epiphyte load, midstory stem count, ground-cover stem count, total epiphyte load, total basal area) were correlated with adult common coqui density. Eucalyptus plantations in montane regions of Puerto Rico provide suitable habitat for the common coqui. However, suitability may be linked to threshold basal area levels of 18-28 m 2 /ha.