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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 San Carlos de Bariloche

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: 605242
  Adult

San Carlos de Bariloche
Río Negro
Argentina
03/05/2020
Peter Vidana
Foto
Photography ID: 485387
  Immature

San Carlos de Bariloche
Río Negro
Argentina
02/13/2018
Horacio Alberto Garcia
Foto
Photography ID: 481174
  Juvenile

San Carlos de Bariloche
Río Negro
Argentina
02/13/2018
Horacio Alberto Garcia
Foto
Photography ID: 412827
  Juvenile

San Carlos de Bariloche
Río Negro
Argentina
01/25/2020
Angel Siguen
Foto
Photography ID: 412826
  Adult

San Carlos de Bariloche
Río Negro
Argentina
01/25/2020
Angel Siguen
Foto
Photography ID: 309449
  Juvenile

San Carlos de Bariloche
Río Negro
Argentina
12/24/2018
Iván Eroles
Foto
Photography ID: 240305
  Adult

San Carlos de Bariloche
Río Negro
Argentina
01/12/2018
Iván Eroles
Foto
Photography ID: 80616
  Adult

San Carlos de Bariloche
Río Negro
Argentina
02/02/2015
Diana Weyland



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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
221208617/11/2024ArgentinaRío NegroCerro Catedral, San Carlos de BarilocheMaría Del Carmen Fabeiro
212128620/07/2024ArgentinaRío NegroSan Carlos de Bariloche2Bc_pajareritos Bandurrias Rheas
212123120/07/2024ArgentinaRío NegroSan Carlos de Bariloche2Axel De Torres Curth
211638220/07/2024ArgentinaRío NegroOnas 5785, San Carlos de Bariloche1Bc_pajareritos EcoRegistros
194696014/01/2024ArgentinaRío NegroSan Carlos de Bariloche1Mariano Costa
192464006/12/2023ArgentinaRío NegroAcceso Cerro Otto, San Carlos de Bariloche1Gustavo Fernando Durán
182042606/03/2023ArgentinaRío NegroArroyo Gutiérrez, San Carlos de Bariloche1Jorge Schlemmer
154680002/02/2022ArgentinaRío NegroCerro Catedral, San Carlos de Bariloche1Pablo Bruni
154678328/01/2022ArgentinaRío NegroCerro Otto, San Carlos de Bariloche1Pablo Bruni
152364119/12/2021ArgentinaRío NegroSan Carlos de Bariloche1Guillermo Enrique Rost
Page 1

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Citation recommended:

EcoRegistros. 2026. Variable Hawk (Geranoaetus polyosoma) - Species sheet. Acceded from https://www.ecoregistros.org on 10/03/2026.