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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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Records from Buenos Aires

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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Latest feeding records




Last published photographs

Foto
Photography ID: 660420
  Adult

Nicolás Levalle
Buenos Aires
Argentina
08/23/2025
Gustavo Abel Larracoechea
Foto
Photography ID: 648120
  Adult

General Villegas
Buenos Aires
Argentina
08/05/2025
Silvio Lamothe
Foto
Photography ID: 647429
  Juvenile

Partido de Necochea
Buenos Aires
Argentina
08/11/2025
Ramon Moller Jensen
Foto
Photography ID: 647427
  Immature

Partido de Necochea
Buenos Aires
Argentina
08/11/2025
Ramon Moller Jensen
Foto
Photography ID: 642452
  Immature

Tandil
Buenos Aires
Argentina
08/31/2019
Fernando Rasmussen
Foto
Photography ID: 641237
♂ ♀
  Adult

Partido de Tres Arroyos
Buenos Aires
Argentina
06/23/2013
Fernando Rasmussen
Foto
Photography ID: 636040
  Juvenile

Claromecó
Buenos Aires
Argentina
05/02/2025
Carlos F. Danti
Foto
Photography ID: 609720
  Immature

Acceso A Balneario San Cayetano
Buenos Aires
Argentina
08/03/2024
José Luis Ianiro



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Last Vocalizations published




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Last Filmings published


Video ID: 1956
  Adult

Balcarce
Buenos Aires
Argentina
07/10/2016
Mateo Alberto Gual



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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
244106301/03/202611:55ArgentinaBuenos AiresRuta Provincial 2271Santiago Juan Torres
242283623/01/2026ArgentinaBuenos AiresSan Clemente del Tuyú1Román Montero
238859523/08/2025ArgentinaBuenos AiresCamino a Chapalcó, Nicolás LevalleGustavo Abel Larracoechea
234426918/08/202510:00ArgentinaBuenos AiresCamino de ingreso a Gorchs, Gorchs1Ricardo Juliano
234943416/08/2025ArgentinaBuenos AiresEntre Reta y Claromecó, Camino rural en RetaPatricia Gabriela Mancilla Iglesias
233996811/08/2025ArgentinaBuenos AiresParque eolico Necochea, Partido de NecocheaRamon Moller Jensen
234306705/08/2025ArgentinaBuenos AiresLaguna entre General Villegas y Piedritas, General VillegasSilvio Lamothe
238798301/08/2025ArgentinaBuenos AiresCamino corto Pehuen Co, Partido de Coronel RosalesGustavo Abel Larracoechea
231253621/06/2025ArgentinaBuenos AiresAcceso Balneario Orense, Tres Arroyos1Gabriel Carbajales
231238420/06/2025ArgentinaBuenos AiresRuta Prov. 227, Lobería2Gabriel Carbajales
Page 1

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Citation recommended:

EcoRegistros. 2026. Variable Hawk (Geranoaetus polyosoma) - Species sheet. Acceded from https://www.ecoregistros.org on 11/04/2026.