The Green-headed Hillstar, Oreotrochilus estella stolzmanni, 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...

 found in the Andes

Andes

The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...

 in far southern Ecuador

Ecuador

Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...

 and northern and central Peru

Peru

Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....

 in alpine grassland and scrub at altitudes of 3600 to 4200 m (11,811 to 13,779.5 ft).

It is usually considered a subspecies

Subspecies

Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 of 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...

, Oreotrochilus estella, but the male of that species has duller upperparts and a brown (not black) line to the central underparts.

The binomial name commemorates Polish

Poland

Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

 ornithologist

Ornithology

Ornithology is a branch of zoology that concerns the study of birds. Several aspects of ornithology differ from related disciplines, due partly to the high visibility and the aesthetic appeal of birds...

 Jan Sztolcman

Jan Sztolcman

Jan Sztolcman was a Polish ornithologist. Sztolcman was born in Warsaw. In 1875 he travelled to Peru on behalf of the zoological museum of Warsaw University. He died in Warsaw....

(Jean Stanislaus Stolzmann).