Biogeographical analysis of the avifauna in the lower western Rio Negro region in the Brazilian Amazon

This study makes a detailed biogeographical analysis of Central Amazon avifauna west of the Rio Negro, where Parque Nacional do Jau (PNJ) is located. The geographical distribution of 383 bird taxa (species or subspecies) recorded in PNJ was analyzed through qualitative and quantitative biogeographic methods (cluster analysis and parsimony analysis of endemicity). Results showed that the avifauna of PNJ is strongly influenced by the northwestern and western regions of the Amazon Basin. Three biogeographic units were identified and PNJ grouped with sites in the upper Orinoco river and Guiana. Similarly, JNP grouped with the upper Orinoco river and Guiana is the sister-group in the area cladogram with strongest support. Different sub-groups of species reveal area cladograms with different topologies, suggesting complex scenarios of avifauna diversification. These scenarios may have been influenced by geological events occurring during the Miocene and Pleistocene. In this study was identified an area of endemism previously not described for the Amazon, the Rio Negro endemic area. The avifauna of PNJ is representative of the northwestern and western Amazon and has taxa with distributions restricted to the central region of the Amazon, reinforcing its importance in protecting the biodiversity of the Amazon.