During 2008-2011, we conducted systematic avifaunal inventories in five localities in the Pacific, Andean and Amazon regions of the Nariño department, Colombia. Of the species registered, we report new and important distribution information for 10 species. We recorded, using visual and photographic observations, one new species and subspecies for Colombia: Fluvicola nengeta and Furnarius leucopus cinnamomeus, with an additional seven new species and range extensions for Nariño: Damophila julie feliciana, Sittasomus griseicapillus, Cercomacra nigricans, Muscisaxicola alpinus, Pitangus sulphuratus, Dacnis lineata and Sturnella militaris. The presence of Iridisornis analis, previously known for Colombia through sight records without documentation, was confirmed based upon the capture and photographic evidence of one individual. The remarkable richness of its avifauna (1048 species), along with the accelerated habitat loss due to human interference, make Nariño a priority region for ornithological research and bird conservation.