Ouvindo os coros da avifauna do Parque Nacional da Serra da Canastra (MG)

Abstract

The substantial vocal activity of birds during the first hours of the morning and afternoon has been the object of curiosity for both scientists and non-scientists for centuries, and many studies have been done in this subject. In Brazil, however, this is a topic of incipient investigation, despite the country’s rich avifauna. In this study, we analyzed the bird’s vocal activity at a Cerrado region (Serra da Canastra National Park, MG, Brazil). Eight points were sampled with autonomous recording units (ARU’s) obtaining 128 hours of audio, one at dawn and the other at dusk, both from the same day for two days per month, for four consecutive months. For each audio file we registered the sonotype richness (different vocal types) and their number of repetition (number of vocalisations). 34 bird species of 20 families were identified out of 95 different sonotypes. The number of sonotypes per file presented a high correlation with the number of species (0.966) and on the generated model (Theil-Sen, p < 0.0001) the number of sonotypes directly predicted the number of species, with the correlation coefficient between predicted and real values being 0.944. This result indicates the potential of sonotype evaluation (or counting) as a proxy of bird species richness. There was no difference in the number of vocalisations between the sampled points. A higher vocal activity at the morning chorus was observed in relation to the afternoon’s, but there was no significant difference on the detected sonotype and species richness. The species Rhynchotus rufescens presented the highest amount of vocalisations (n = 10.833), and along with Sicalis citrina, were the two only species present in the 8 sampled points. Cistothorus platensis presented the most varied vocal repertoire (20 different sonotypes). 23,5% of the species detected on a rapid ecological evaluation in the same area were also detected in the present study, and the majority of the species detected in our study is also present in other lists made in larger areas for longer periods of time, however, mostly only with photographic records. The first documental records for Accipiter striatus and Gallinago undulata for this area were obtained in the present study.