Glittering-bellied emerald

The glittering-bellied emerald (Chlorostilbon lucidus) is a species of hummingbird in the "emeralds", tribe Trochilini of subfamily Trochilinae. It is found in Argentina, Bolivia, Brazil, Paraguay, and Uruguay.

The male glittering-bellied emerald is 9.5 to 10.5 cm (3.7 to 4.1 in) long and weighs 3 to 3.8 g (0.11 to 0.13 oz). Females are 7.5 to 8.5 cm (3.0 to 3.3 in) long and weigh 3 to 4.5 g (0.11 to 0.16 oz). Both sexes have a short straight bill. The male's is red with a black tip; the female's is black on its outer half and red on the inner.

Males of the nominate subspecies have a dull bronzy green forehead and crown, slightly golden green upperparts, grass green uppertail coverts, and a slightly forked dark steely blue tail. It has a blue-green throat and upper breast and a bronze to bronzy green belly that is more iridescent than the upperparts. The nominate female's forehead, crown, and upperparts are slightly golden green and its uppertail coverts grass green. The innermost pair of tail feathers have green inner and blue outer halves. The other four pairs are steel blue with gray tips in a V shape. It has a grayish white streak behind the eye and a whitish throat that darkens to pale brownish gray on the breast and belly.

Subspecies C. l. beflepschi has pure green rather than golden green upperparts. C. l. pucherani has the same plumage as the nominate but is slightly smaller. When considered separately, C. l. igneous has many glittering orange-gold speckles on its belly.

The song is "a high-pitched, cricket-like trill...repeated at intervals." Its principal call, given when feeding or hovering, is "a short dry, scratchy rattle, 'trrrr' or 'krrr'." It also makes "a fast descending series of 'tsee-tsee-tsee-tsu-tsew-tsew-tsew' notes" during agonistic encounters.