Anurans and birds rely on sound for a number of social behaviors. Species that use roadside habitats are exposed to traffic noise that can mask important social signals and directly affect the community diversity and composition. We evaluate the impact of traffic noise on anuran and bird species richness, species occurrence, and composition in Puerto Rico, where there is a high density of highways and cars that generate high levels of noise pollution. We compared paired forest sites near (100 m, n=20, dB>60) and far (>300 m, n=20, dB<60) from highways, with similar vegetation structure, but different levels of noise. We found that the anuran community was not affected by traffic noise. In contrast, bird species richness and occurrence were significantly lower in sites near the highway, and bird species composition also varied significantly. Bird species with low-frequency songs were only detected in sites far from highways. The differences in the ecology and communication behavior between anurans and birds could explain these results. Anurans mainly call at night, when traffic activity was low. In contrast, bird singing activity occurs during the day and overlaps with the high levels of traffic noise. In addition, in natural habitats, Puerto Rican anurans occur at high densities and form noisy choruses (>80 dB), which may allow them to tolerate high levels of anthropogenic noise.

Protected area zoning is a management strategy used to define and delimit land units for specific purposes, such as critical areas for conservation and areas for recreation activities. Nevertheless, human activities in and around protected areas produce anthropogenic noise that is difficult to mitigate and control. To assess the efficacy of protected area zoning in preserving natural soundscapes, controlling anthropogenic noise intrusion, and conserving biodiversity in El Yunque National Forest, Puerto Rico, I simultaneously sampled three management zones (protected, recreational, and buffer) with passive acoustic monitoring and conducted a soundscape analysis. There was no difference in the overall acoustic space used among the three management areas, but compositional differences among the soundscapes were detected. Such variation was related to differences in species composition along the elevation gradient, habitat transformation, and anthropogenic noise. Anthropogenic noise was more conspicuous in the buffer and recreational areas, where many bird species are classified as highly vulnerable to noise. Although the management zones in El Yunque National Forest were not created for the purpose of noise control, management is shown to be useful for minimizing noise intrusion in the strictly protected zone. In recreational and buffer areas, complementary strategies such as traffic limitations, limiting access to specific areas, and noise reduction educational programs should be implemented to maintain the natural soundscape while conserving biodiversity. Finally, the noise vulnerability classification proposed in this study could be a useful tool for assisting managers and researchers in defining priority strategies for sensitive species that require special attention and protection.

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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.