Space and time are two of the main dimensions of the ecological niche. Because of their high dependence upon aquatic environments during breeding activity, anuran assemblages are interesting models for studying inter-populational relationships. The overlap in habitat use could be particularly high, especially for seasonal species and among taxa that share a common phylogenetic history. Three species of the Leptodactylus fuscus group occur in a semi-permanent pond at Cerro Verde (Rocha, Uruguay): L. latinasus, L. mystacinus and L. gracilis. The aim of this work was to describe the spatial and temporal calling patterns of the three species and the effects of environmental conditions upon them on a daily scale. Their relative abundance was quantified over four weeks (December 2004–January 2005) during the first half of the night along a transect using acoustic surveys. Nestedness, segregation, Jaccard's index and association analysis were calculated, revealing a nested pattern with low overlap between species in the occupation of microhabitats. On the temporal axis, the calling behavior of the species seems to be better described by the time of night than by temperature, humidity, or atmospheric pressure. These analyses also showed a non-linear association of activity with time of night, indicating that higher activity occurs at different hours for each species.