 Both sexes have a straight black bill, a forked tail and white pufflegs, from which the common name is derived.There is no characteristic vocalization; the species is generally quite silent, but may on occasion emit a monotonous and metallic "tseet tseet tseet" when it flies away.The black-breasted puffleg is endemic to north-western Ecuador, where it currently appears restricted to the ridge crests of the Pichincha Volcano, the Cordillera de Toisán, Esmeraldas and Imbabura.