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Interactions between heterospecific species with similar sexual signals can lead to errors in mate attraction and species recognition. As a consequence sexual signals might diverge to reduce communication errors. Since high-density populations create more noise than low-density populations we hypothesize that individuals should suffer less acoustic interference from sympatric congeners with low-density populations than higher density populations of congeners. Even though species might be sympatric at multiple sites, only populations at sites with a relatively high abundance of both species should require one species to make vocal adjustments that minimize acoustic interference. To test this hypothesis we studied Eleutherodactylus coqui populations in the presence of relatively high numbers of E. portoricensis and in the presence of relatively low abundance of E. portoricensis. We found subtle differences in advertisement calls of E. coqui at locations where E. portoricensis had relatively high a...

The bird and amphibian communities of Puerto Rico have high levels of diversity and endemism. Although Puerto Rico has a very high density of roads and high levels of noise pollution, presently 40% of the island is covered in forest. I will address the following questions: Do high levels of anthropogenic noise change species composition of amphibians and birds? Are amphibians and birds modifying the time of calling and/or characteristics of their vocalization in response to anthropogenic noise? I collected sound recordings in two habitats. For recordings I used the automated recording devices developed by our research group. Each recording device was programmed to record for 7 consecutive days; 1 min every 20 min. Previous results showed that noise influences the bird community composition in secondary lowland forest sites, but not in karst forest. Another possibility is that bird and amphibian use other strategies to minimize the effect of noise. This can involve evolutionary changes in signal characteristics, as a long term adaptation or the species may be adjusting signal traits in response to variations in noise levels as a short term adaptation. I will answer these questions when I do analyzing all data.