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Variable Hawk

Geranoaetus polyosoma
(Quoy, JRC; Gaimard, JP, 1824)
Aguilucho Común
Gavião-de-costas-vermelhas

Family: Accipitridae
Order: Accipitriformes
Class: Aves
Phylum / Division: Chordata
Kingdom: Animalia

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Conservation status according to BirdLife International: Least Concern

Other common names: Ñanco, Aguilucho Variable.

Synonyms: Buteo polyosoma, Falco polyosoma.

Subspecies:


Description: It is a large, long-winged raptor with a slender profile and remarkable plumage variability. Individuals range from mostly ash-gray to rufous or chestnut tones, with lighter or darker underparts depending on morph. In flight, it is recognized by its slightly raised wings forming a shallow “V”, relatively short tail, and pale patches at the base of the primaries. Juveniles tend to be browner and more streaked.

Geographic distribution: It is widely distributed across South America, from southern Colombia and Venezuela to southernmost Chile and Argentina. It is especially common along the Andes, but also inhabits Patagonian steppes, intermontane valleys, and open lowlands.

Habitat: It occupies open and semi-open habitats, including grasslands, shrublands, agricultural areas, and mountainous regions. It tolerates a broad altitudinal range, from sea level to over 4,000 m, efficiently using thermal currents for soaring.

Diet: It is an opportunistic predator, feeding mainly on small mammals (particularly rodents), medium-sized birds, reptiles, and large insects. It also scavenges when opportunities arise, which increases its dietary flexibility.

Behavior: Usually seen alone or in pairs, though it may gather where food is abundant. It spends long periods soaring with a powerful yet economical flight, and maintains large territories during the breeding season.

Nesting: It builds large stick nests, typically on rocky cliffs, escarpments, or occasionally tall trees and human-made structures. Clutches usually consist of one to two eggs, with shared parental care and an extended fledging period.

Conservation status: It is classified as Least Concern globally due to its wide range and generally stable populations, although local threats include persecution, electrocution, and habitat alteration.


Author of this compilation: EcoRegistros – 15/12/2025




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Last Vocalizations published



Audio playerUserDateCountryProvincePlaceSexLife stageIt was observedDetails
Emilio Martin Perez12/27/2019ArgentinaMendozaReserva Natural VillavicencioN/AAdultNoNo



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 Reports


 Detail of places sorted by number of records








Page 1
Record IDDateExact timeCountryProvince / departmentPlaceFilmedPhotographedRecorded vocalObservedHeardWounded or deadNumber of individualsUser or BibliographyDetail
243668617/02/2026ArgentinaMendozaCabañas san jose de Pemehue, San Rafael2Emilio Martin Perez
241762710/01/2026ArgentinaMendozaReserva Natural Villavicencio1Emilio Martin Perez
228296304/05/202512:54ArgentinaLa RiojaCiudad de Mar del Plata 41, La Rioja1Emilio Martin Perez
228449001/05/2025ArgentinaTucumánCamino a El Infiernilllo5Emilio Martin Perez
225774228/02/2025ArgentinaMendozaReserva Natural Villavicencio1Emilio Martin Perez
224280531/01/2025ArgentinaMendozaReserva Natural Villavicencio2Emilio Martin Perez
210829411/07/2024ArgentinaMendozaPlanta de tratamiento de efluentes El Paramillo, Lavalle1Emilio Martin Perez
210206525/06/2024ArgentinaMendozaReserva Natural Villavicencio1Emilio Martin Perez
203904524/05/2024ArgentinaMendozaReserva Natural VillavicencioEmilio Martin Perez
171096825/01/2023ArgentinaMendozaCamino Francisco Guiñazú (-32,986335, -69,351952)1Emilio Martin Perez
Page 1

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Citation recommended:

EcoRegistros. 2026. Variable Hawk (Geranoaetus polyosoma) - Species sheet. Acceded from https://www.ecoregistros.org on 18/03/2026.