Abstract Birds are the best-known vertebrate group, although many localities in the world are considered to be knowledge gaps. This is the case of many little-known environments in the Amazon biome, the world’s largest tropical forest. Here, we present a survey of birds in the upper Purus basin, comprising the municipalities of Manoel Urbano and Feijó in the Brazilian state of Acre, and Boca do Acre and Pauini in the state of Amazonas. In this region, poorly-studied habitats, such as open rainforest dominated by palms or bamboo, still predominate. We recorded 452 bird species during 45 field trips between May and July in 2016, and June to August in 2017. Twenty-four of these species are associated with bamboo habitat, 28 are endemic to the southwestern Amazon basin, and seven are threatened with extinction. This high diversity is typical of the western Amazon basin, one of the richest regions in the world in the number of species, due to the heterogeneity of the local environments. The data presented here highlight the importance of the region for the conservation of birds, including species typical of the western Amazon, some of which are still poorly-known.