| Ecuadorian hillstar, Andean hillstar, White‑sided hillstar, Wedge‑tailed hillstar, Black‑breasted hillstar|
The hillstars are hummingbirds of the genus Oreotrochilus. They are native to the Andes in South America.
The white-tailed hillstar (Urochroa bougueri) is not closely related.
The birds are approximately 13 centimetres (5.1 in) in length with fairly long, slightly decurved black bills. They are sexually dimorphic. The male usually has an iridescent green throat, or bluish-purple in the Ecuadorian hillstar, with dull greenish upperparts and pale flanks. The central underparts are usually black, but are brown in the Andean hillstar. The tail is usually dark with a contrasting white pattern; the pattern is cinnamon in the wedge-tailed hillstar, and the tail is entirely dark in the black-breasted hillstar. The female is duller, with a whitish throat densely spotted with green, white, buff, or cinnamon underparts, and a dark tail with a white pattern.
These highly territorial hummingbirds are found in temperate and alpine grassland, scrub and woodland at altitudes of 1,200 to 5,200 metres (3,900 to 17,100 ft). The Ecuadorian hillstar has been observed nesting at high altitudes on the cliffs of Cotopaxi. This species is known to nest colonially.
Many hillstars feed mainly on shrubs of the Andean plant genus Chuquiraga, and some species may be limited to them.
The genus has undergone allopatric speciation.
There are six taxa in the genus.Ecuadorian hillstar (Oreotrochilus chimborazo)
Andean hillstar (Oreotrochilus estella)
Green-headed hillstar (Oreotrochilus estella stolzmanni)
White-sided hillstar (Oreotrochilus leucopleurus)
Black-breasted hillstar (Oreotrochilus melanogaster)
Wedge-tailed hillstar (Oreotrochilus adela)
The Ecuadorian hillstar may be treated as a subspecies of the Andean hillstar.