The Andean hillstar (Oreotrochilus estella) is a species of hummingbird in the family Trochilidae. It is found in grassland, scrub and woodland in the Altiplano of southern Peru, Bolivia, northern Chile, and north-western Argentina. It often includes the green-headed hillstar as a subspecies, but the male of that species has a black (not brown) stripe to the central underparts, and its upperparts are greener. Additionally, the green-headed hillstar is more closely related to the black-breasted hillstar and blue-throated hillstar than the Andean hillstar.
|Male above, female below|
|Combined distribution (green) of Andean and green-headed hillstars in South America|
The species is unusually well adapted to cold nights in the Andes, which it survives by reducing its metabolic rate utilizing a state of torpor to something like that of hibernation in sheltered niches facing the rising sun.
- BirdLife International (2012). "Oreotrochilus estella". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- Handbook of the Birds of the World. Vol. 5, J. del Hoyo, A. Elliott & J. Sargatal (eds.), Barcelona, 1999.
- Sornoza-Molina, F., J. F. Freile, J. Nilsson, N. Krabbe & E. Bonaccorso. 2018. A striking, critically endangered, new species of hillstar (Trochilidae: Oreotrochilus) from the southwestern Andes of Ecuador. Auk 135(4): 1146–1171.