White-Vented Plumeleteer

The white-vented plumeleteer is a hummingbird found in Panama, Colombia, Venezuela, Ecuador and Peru. There are five subspecies, four of which are found in Colombia. 

White-vented plumeleteer range - from Wikipedia

Wikipedia notes: "Males have mostly dark metallic green upperparts with a bronzy tinge to the crown and coppery bronze uppertail coverts. Their upper breast is bluish, lower breast bright metallic green, the lower belly whitish, and the undertail coverts long and white. Their tail is blue-black with a bronze gloss on the central feathers...[F]emales are paler metallic green above and gray below with green speckles on the side. Their tail is like the males' with the addition of dull gray tips on the outer feathers."

This photo shows the blue on the neck and the fluffy-white undertail covert.

This photo shows the blue-black tail.

I saw them at Tinamu Reserve in Colombia, outside Manizales. They were distinguishable by their white undertail-covert.