Acoustic niche occupied by birds associated to cerrado and gallery forest in the Brasilia region, federal district

The communication between birds is a fundamental aspect of interacting individuals, either during reproduction or defense of resources and territories. The acoustic niche theory advocates that each species have been selected to have an optimal vocalization, which enhances the transmission of sound communication. Thus, we expect that different species occupy different acoustic spaces so as to avoid interference from other species during the communicative process. In this study, we evaluated two aspects of the acoustic niche theory: (1) if bird communities associated to cerrados and gallery woods in Brasília-DF are in fact structured in distinct acoustic spaces and (2) if that structure repeats itself between the environments. We used digital automatic recorders (SongMeter 2 – Wildlife Acoustics) to register birds species in 15 points of cerrado and 15 points of gallery forest. We extracted six measures (low frequency, high frequency, peak frequency, frequency variation, song length and average entropy) using the program Raven PRO. We compared the structure of 102 sonotypes through a PCA between environments and within each environment. Our results show that cerrado’s and gallery forest’s communities are different in acoustic structure and it is possible to characterize the acoustic space (determined by the scores of the two first components) of each species. The cerrado exhibits a clearer distinction than the wood gallery though. Our results corroborate the hypothesis that songs vary according to environment structure.