White-throated mountaingem

The white-throated mountaingem or white-throated mountain-gem (Lampornis castaneoventris) is a species of hummingbird in tribe Lampornithini of subfamily Trochilinae. It is endemic to the highlands of Costa Rica and Panama.

The grey-tailed mountaingem is about 12 cm (4.7 in) long and weighs about 5 to 6 g (0.18 to 0.21 oz). It has a medium-length straight black bill, dark cheeks, and a white stripe behind the eye. Males have mostly dark bronzy green upperparts with an emerald green crown and a black to bluish black tail. Their chin and throat are white, the sides of the neck and upper breast bright green, and the lower breast and vent area dark gray. Females have entirely bright green upperparts. Their central tail feathers are dark metallic to bronze green and the outer ones paler. Their throat and belly are dark rufous and the undertail coverts are gray with white or buff edges.