White-sided hillstar

The white-sided hillstar (Oreotrochilus leucopleurus) is a species of hummingbird in the "coquettes", tribe Lesbiini of subfamily Lesbiinae. It is found in Argentina, Bolivia, Chile.

The white-sided hillstar is 13 to 15 cm (5.1 to 5.9 in) long and weighs 7.9 to 8.4 g (0.28 to 0.30 oz). Adults have a medium length slightly decurved black bill. The adult male has drab brown upperparts. It has a shiny green gorget with a black border that separates it from the white breast and belly. The belly has a wide blue-black stripe down its middle into the vent area. The somewhat rounded tail is bronzy black and its outer feathers have white at the base. The female is also dull brown above, and below as well. Its throat is pale with fine dark speckles. The tail is greenish black and the outer three or four pairs of feathers have much white at the bases and tips. The juvenile is overall more grayish than the adult and the male has a dark blue-green gorget.