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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 El Bolsón

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 published photographs

Foto
Photography ID: 293787
  Adult

El Bolsón
Río Negro
Argentina
10/15/2018
Edgar Romeo
Foto
Photography ID: 272385
 
El Bolsón
Río Negro
Argentina
11/20/2009
Vicente Piccirillo
Foto
Photography ID: 250732
  Adult

El Bolsón
Río Negro
Argentina
01/29/2018
Elsa Longo
Foto
Photography ID: 248816
  Adult

El Bolsón
Río Negro
Argentina
01/29/2018
Guillermo Marcaida
Foto
Photography ID: 107060
  Adult

El Bolsón
Río Negro
Argentina
07/16/2015
Adrian Braidotti



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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
105949119/05/2019ArgentinaRío NegroEl Bolsón1Julian Quillen Vidoz
82484915/10/2018ArgentinaRío NegroEl BolsónEdgar Romeo
105958301/04/2018ArgentinaRío NegroEl Bolsón1Julian Quillen Vidoz
105958226/03/2018ArgentinaRío NegroEl Bolsón2Julian Quillen Vidoz
70645029/01/2018ArgentinaRío NegroEl BolsónElsa Longo
70186429/01/2018ArgentinaRío NegroEl BolsónGuillermo Marcaida
105958107/01/2018ArgentinaRío NegroEl Bolsón4Julian Quillen Vidoz
105949001/01/2018ArgentinaRío NegroEl Bolsón1Julian Quillen Vidoz
105958026/12/2017ArgentinaRío NegroEl Bolsón1Julian Quillen Vidoz
105957908/12/2017ArgentinaRío NegroEl Bolsón3Julian Quillen Vidoz
Page 1

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Citation recommended:

EcoRegistros. 2026. Variable Hawk (Geranoaetus polyosoma) - Species sheet. Acceded from https://www.ecoregistros.org on 12/03/2026.