White-sand forests (WSF hereafter) include several types of stunted and open forest growing on bleached sandy soils throughout Amazonia; despite their widespread distribution, WSF occur predominantly in the upper Rio Negro drainage (NW Brazil, SE Colombia, and S Venezuela). Smaller and isolated WSF patches located in SW. Brazilian Amazonia have not been studied systematically by ornithologists; therefore, some important ornithological results obtained during a field-trip to a WSF patch in the extreme SW. corner of the state of Amazonas, centered at 7º22'33.2"S and 73º00'42.5"W, are presented here. The first records of Hemitriccus striaticollis (Lafresnaye, 1853) (Aves, Tyrannidae) and Xenopipo atronitens Cabanis, 1847 (Aves, Pipridae) for SW. Brazilian Amazonia are presented, along with additional records of the following little known or rare species inhabiting this region: Formicivora grisea (Boddaert, 1783) (Aves, Thamnophilidae), Conopias parvus (Pelzeln, 1868) (Aves, Tyrannidae), and Heterocercus linteatus (Strickland, 1850) (Aves, Pipridae). As verified in WSF patches distributed throughout N. Peru, the WSF avifauna occurring in SW. Brazilian Amazonia is also highly influenced by species closely associated with the upper Rio Negro drainage. However, a second distinct biogeographic influence was also noted: that of species whose distribution's strongholds are located in central and E. Amazonia, S. of the Amazon river. The WSF avifauna of SW. Brazilian Amazonia is still poorly known; future ornithological surveys of isolated WSF patches in this region could lead to new range extensions and even to the discovery of unnamed taxa.
Formicivora grisea; Hemitriccus striaticollis; Conopias parvus; Xenopipo atronitens; Heterocercus linteatus