The avifauna on the north bank of the Putumayo River in Colombia is one of the most poorly known in western Amazonia. In February 2017 we spent nine days conducting ornithological field work in and around the community of El Encanto, dpto. Amazonas. We present novel distributional information for six species, the most significant of which concern range extensions for Whiteshouldered Antshrike Thamnophilus aethiops, Imeri Warbling Antbird Hypocnemis flavescens and Black-headed Antbird Percnostola rufifrons minor. We discuss these records in the context of recent ornithological work on the south bank of the Putumayo in Peru and address their biogeographical significance, especially with regards to the definition of areas of endemism in western Amazonia and the role of the Putumayo River as a distributional barrier. Our findings underscore the need for continued ornithological field work in the Putumayo–Caquetá interfluvium and indeed the Colombian Amazon as a whole.