The Buff-tailed Sicklebill has buff outer tail feathers and a streaked underside. It feeds on nectar in the understory of humid forests.
The outer tail feathers are buff, fading to white at the tips, and the cheeks and underside are streaked buff and brownish black. The back and wings have a bronze tone.
It uses the understory and edges of humid forest and older secondary growth, feeding on nectar. The account also lists riverside forest among Peruvian habitats.
An extinction-risk assessment has not been added yet.