The White-sided Hillstar (Oreotrochilus leucopleurus) is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of hummingbird

Hummingbird

Hummingbirds are birds that comprise the family Trochilidae. They are among the smallest of birds, most species measuring in the 7.5–13 cm range. Indeed, the smallest extant bird species is a hummingbird, the 5-cm Bee Hummingbird. They can hover in mid-air by rapidly flapping their wings...

 in the Trochilidae family. It is the southernmost species of hillstar, being found in grassland and scrub at altitudes of 1200 to 4000 m (3,937 to 13,123.4 ft) in far southern Bolivia

Bolivia

Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...

, Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

 and western Argentina

Argentina

Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

. It resembles the Andean Hillstar

Andean Hillstar

The Andean Hillstar is a species of hummingbird in the Trochilidae family. It is found in grassland, scrub and woodland in the Altiplano of southern Peru, Bolivia, northern Chile, and north-western Argentina...

, but the male of that species has a far narrower brown (not black) line to the central belly.