The buff-tailed coronet (Boissonneaua flavescens) is a species of hummingbird in the "brilliants", tribe Heliantheini in subfamily Lesbiinae.

The buff parts of both sexes of B. f. tinochlora have a cinnamon cast and there is more bronze on the tail feathers' tips.

The nominate subspecies of buff-tailed coronet is found from the Andes of western Venezuela's Mérida state south and west through all three Andean ranges of Colombia.

[5] The buff-tailed coronet is highly territorial, though it may share feeding at a flowering tree with other hummingbirds.

It builds a cup nest of moss and lichen that is usually attached to a branch between 3 and 10 m (10 and 30 ft) above the ground.

What is thought to be the buff-tailed coronet's song is "a continuous series of single high-pitched 'tsit' notes".

It also makes a "squeaky twittering, with rising piping notes and stuttering rattles", especially when interacting with other hummingbirds.