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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 published photographs

Foto
Photography ID: 122885
  Adult

Puelches
La Pampa
Argentina
10/30/2015
Federico Burgos Bauer
Foto
Photography ID: 105073
  Juvenile

Guatraché
La Pampa
Argentina
07/04/2015
Federico Burgos Bauer
Foto
Photography ID: 104813
  Juvenile

Guatraché
La Pampa
Argentina
07/02/2015
Federico Burgos Bauer
Foto
Photography ID: 81715
  Adult

Partido de Villarino
Buenos Aires
Argentina
02/07/2015
Federico Burgos Bauer
Foto
Photography ID: 70304
  Adult

Guatraché
La Pampa
Argentina
05/26/2014
Federico Burgos Bauer



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Page 1
Record IDDateExact timeCountryProvince / departmentPlaceFilmedPhotographedRecorded vocalObservedHeardWounded or deadNumber of individualsUser or BibliographyDetail
35566930/10/2015ArgentinaLa PampaPuelchesFederico Burgos Bauer
30205604/07/2015ArgentinaLa PampaCamino cercano a la Laguna de Guatraché., GuatrachéFederico Burgos Bauer
30147502/07/2015ArgentinaLa PampaLaguna Guatraché, GuatrachéFederico Burgos Bauer
23837307/02/2015ArgentinaBuenos AiresMayor Buratovich, Partido de VillarinoFederico Burgos Bauer
20400826/05/2014ArgentinaLa PampaAlrededores del pueblo, GuatrachéFederico Burgos Bauer
Page 1

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Citation recommended:

EcoRegistros. 2026. Variable Hawk (Geranoaetus polyosoma) - Species sheet. Acceded from https://www.ecoregistros.org on 19/03/2026.