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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 Puerto Deseado

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: 537519
  Juvenile

Puerto Deseado
Santa Cruz
Argentina
03/11/2023
Santos Di Mauro
Foto
Photography ID: 537517
  Adult

Puerto Deseado
Santa Cruz
Argentina
03/11/2023
Santos Di Mauro
Foto
Photography ID: 396746
  Adult

Puerto Deseado
Santa Cruz
Argentina
01/30/2020
Enrique Sanz
Foto
Photography ID: 393643
  Adult

Puerto Deseado
Santa Cruz
Argentina
03/16/2020
Jorge Schlemmer
Foto
Photography ID: 375129
  Adult

Puerto Deseado
Santa Cruz
Argentina
01/06/2020
Andrés Cecconi
Foto
Photography ID: 320049
  Adult

Puerto Deseado
Santa Cruz
Argentina
01/15/2019
Gustavo Daniel González
Foto
Photography ID: 232003
  Adult

Puerto Deseado
Santa Cruz
Argentina
11/19/2017
Cristina Miriam Martorano
Foto
Photography ID: 130428
  Adult

Puerto Deseado
Santa Cruz
Argentina
12/23/2015
Ricardo Juliano
Foto
Photography ID: 111398
  Adult

Puerto Deseado
Santa Cruz
Argentina
08/20/2015
Gustavo Castaing
Foto
Photography ID: 49290
  Adult

Puerto Deseado
Santa Cruz
Argentina
04/23/2014
Christian Altamirano
Foto
Photography ID: 38674
  Juvenile

Puerto Deseado
Santa Cruz
Argentina
02/11/2014
Christian Altamirano



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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
177679211/03/2023ArgentinaSanta CruzPuerto Deseado, Puerto DeseadoSantos Di Mauro
156333817/01/2022ArgentinaSanta CruzEspaña 1611, Puerto Deseado2Eugenia Boggiano
123452616/03/2020ArgentinaSanta CruzCañadón de los Paraguayos, Puerto DeseadoJorge Schlemmer
123989930/01/2020ArgentinaSanta CruzRia Puerto Deseado, Puerto DeseadoEnrique Sanz
117089506/01/2020ArgentinaSanta CruzPuerto DeseadoAndrés Cecconi
112470807/10/2019ArgentinaSanta CruzPuerto DeseadoNicolas Olejnik
151684118/01/2019ArgentinaSanta CruzRia Puerto Deseado, Puerto Deseado1Luis Cesar Tejo
87998318/01/2019ArgentinaSanta CruzRia Puerto Deseado, Puerto Deseado1Daniela Espinosa
89263815/01/2019ArgentinaSanta CruzPuerto DeseadoGustavo Daniel González
68127313/01/2018ArgentinaSanta CruzPuerto Deseado1Guillermo 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 12/03/2026.