Acoustic signals produced by animals can be masked by natural or anthropogenic environmental noise. A high proportion of the current distribution of the glass-frog Hyalinobatrachium fleischmanni (Centrolenidae) overlaps with noisy urban habitats, and this may affect the species acoustic communication. In this work, we analyzed the relationship between changes in anthropogenic noise level throughout the night and the diel acoustic variation (vocalization per time) in H. fleischmanni, within three sites with different noise level. We conducted this study in three sites inside the Rodrigo Facio University Campus, San José, Costa Rica in June 2015. We used an automated recorder per site to record glass-frog vocalizations, from 17:00 to 6:00 h, during two consecutive days, every two weeks, for a month. Simultaneously, we measured the noise levels in dB each hour using a soundmeter. We used linear mixed models to compare the vocalization mean per hour against the noise levels per hour and site. Our results showed that noise levels and H. fleischmanni acoustic activity varied throughout the night. The H. fleischmanni acoustic activity at the noisier site was different from sites with lower noise levels. The highest acoustic activity was found in the less noisy site throughout the sampled period. Although we fail to found a direct relationship between noise level and H. fleischmanni acoustic activity, noise level variation affects vocal activity pattern in this species.

Keywords: acoustic communication; advertisement song; anuran; diel patterns; urban areas.