Greater Rhea Rhea americana


Taxonomic note
Other rheas were previously separated in genus Pterocnemia, on basis mainly of tarsal scutellation and feathered upper tarsus, but genetic studies show them to be closely related to present species, and probably more aptly considered congeneric (Delsuc et al. 2007, SACC 2008); present species has hybridized with R. pennata in captivity. Several subspecies poorly known, and listed ranges remain provisional; birds of E Bolivia and Mato Grosso do Sul (WC Brazil), currently listed for subspecies araneipes, may instead be referable to albescens. Five subspecies recognized.

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.

IUCN Red List criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- - -

Red List history
Year Category Criteria
2022 Near Threatened A2cd+3cd+4cd
2016 Near Threatened A2cd+3cd+4cd
2012 Near Threatened A2cd+3cd+4cd
2008 Near Threatened A2c,d; A3c,d; A4c,d
2004 Near Threatened
2000 Lower Risk/Near Threatened
1994 Lower Risk/Near Threatened
1988 Near Threatened
Species attributes

Migratory status not a migrant Forest dependency does not normally occur in forest
Land-mass type continent
Average mass -

Estimate Data quality
Extent of Occurrence (breeding/resident) 8,740,000 km2 medium
Severely fragmented? no -
Estimate Data quality Derivation Year of estimate
Population size unknown - - -
Population trend decreasing poor inferred 2000-2033
Rate of change over the past 10 years/3 generations (longer of the two periods) 20-29% - - -
Rate of change over the future 10 years/3 generations (longer of the two periods) 20-29% - - -
Rate of change over the past & future 10 years/3 generations (longer of the two periods) 20-29% - - -
Generation length 11.08 years - - -

Population justification: The global population size has not been quantified, but this species is described as 'uncommon to fairly common' (Stotz et al. 1996).

Trend justification: The population is reportedly declining, mainly as a consequence of habitat loss and fragmentation, as well as hunting (Giordano et al. 2010, Bazzano et al. 2014, Kirwan et al. 2021). It has become extinct in Ceará and Rio Grando do Norte in northern Brazil, though parts have now been recolonised by reintroduced individuals (Kirwan et al. 2021).The rate of decline has not been quantified, but it is suspected to be moderately rapid over three generations (33.2 years; Bird et al. 2020) as a consequence of continuing pressures from habitat loss and hunting.

Country/territory distribution
Country/Territory Presence Origin Resident Breeding visitor Non-breeding visitor Passage migrant
Argentina extant native yes
Bolivia extant native yes
Brazil extant native yes
Paraguay extant native yes
Uruguay extant native yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Bolivia Área Natural de Manejo Integrado San Matías
Bolivia KAA-IYA del Gran Chaco
Bolivia Noel Kempff Mercado
Bolivia Loreto
Bolivia Reserva de Inmovilización Iténez
Argentina Salinas Grandes
Argentina Bañados del Quirquincho
Argentina Chaco de Tartagal
Argentina Chaguaral
Uruguay Castillos Lagoon
Argentina Lomas de Olmedo
Argentina Lotes 32 y 33, Maíz Gordo
Argentina Salta Forestal
Argentina Salinas de Ambargasta
Argentina Bañado de Añatuya
Argentina Parque Nacional Copo
Argentina Bañados de Figueroa
Argentina El Cachapé
Argentina Valle Fluvial del Río Paraguay
Argentina La Fidelidad
Argentina Reserva Natural Loro Hablador
Argentina Estancia La Leonor
Argentina Estero Tapenagá
Argentina Parque Provincial Fuerte Esperanza
Argentina Parque Nacional Chaco
Argentina Parque Provincial Pampa del Indio
Argentina Río Bermejito
Argentina Reserva Natural Formosa
Argentina Valle del río Paraguay-Paraná
Argentina Reserva El Bagual
Argentina El Cantor
Argentina Misión Taacaglé
Argentina Fortín Sargento Primero Leyes
Argentina Nacientes de los riachos Monte Lindo y Tatú Piré
Argentina Estancia La Alegría
Argentina Bañado La Estrella Este
Argentina Estancia Guaycolec
Argentina Bañado La Estrella Oeste
Argentina Pilagás III
Argentina Parque Nacional Río Pilcomayo
Argentina Campo San Juan
Argentina Barra Concepción
Argentina Estancia Puerto Valle
Argentina Estancia San Juan Poriahú
Argentina Reserva Natural Rincón de Santa María
Argentina Cuenca del río Aguapey
Argentina Loma Alta
Argentina Parque Nacional Mburucuyá
Argentina Rincón del Socorro-Iberá
Argentina Concepción-Chavarría
Argentina Espinal de Mercedes
Argentina Felipe Yofre
Argentina Extremo noreste de Corrientes
Argentina Región Estancia Oscuro
Argentina Parque Nacional El Palmar
Argentina Perdices
Argentina Nandubaysal-El Potrero
Argentina Pastizales de Ibicuy
Argentina Ceibas
Argentina Selva de Montiel
Argentina Cuña boscosa de Santa Fe
Argentina Bajos Submeridionales
Argentina Dorso Occidental Subhúmedo de Santa Fe
Argentina Reserva Provincial de Usos Múltiples Federico Wildermuth
Argentina San Javier
Argentina Parque Costero del Sur
Argentina Sierras Australes de Buenos Aires
Argentina Villa Iris, Chasicó, Napostá
Argentina Caldenal del Sudoeste de Buenos Aires
Argentina Estepas arbustivas del Sur de Buenos Aires
Argentina Estancia San Ignacio
Argentina Estancia Medaland
Argentina Cuenca del Río Salado
Argentina Bañados del Río Saladillo
Argentina Sierras del Norte Cordobés
Argentina Chancaní y Sierras de Pocho
Argentina Reserva de Uso Múltiple Bañados del Río Dulce y Laguna Mar Chiquita
Argentina Parque Nacional Talampaya
Argentina Reserva de Biosfera de Ñacuñan
Argentina Reserva Provincial Florística y Faunística Bosques Teltecas
Argentina Lagunas de Guanacache
Argentina Pastizales de La Travesía y Buena Esperanza
Argentina Reserva Provincial Parque Luro
Argentina Victorica
Argentina Jagüel del Monte
Argentina Parque Nacional Lihue Calel
Argentina Bañados del Río Atuel
Argentina Villa marítima El Cóndor
Argentina San Antonio Oeste
Brazil Estação Ecológica de Uruçuí-Una
Brazil Parque Nacional da Chapada dos Veadeiros e Adjacências
Brazil Parque Nacional das Emas
Brazil Terra Ronca
Brazil Parque Nacional da Chapada dos Guimarães e Adjacências
Brazil Reserva Particular do Patrimônio Natural SESC Pantanal e Entorno
Brazil Maciço do Urucum e Adjacências
Brazil Rios Negro e Aquidauana
Brazil Alto Rio Juruena
Brazil Jalapão
Brazil Matas Ciliares do Rio do Coco e Afluentes
Brazil Cerrados do Nordeste de Tocantins
Argentina Jaaukanigás
Brazil Campos do Planalto das Araucárias
Brazil Banhado São Donato
Brazil Campos da Região de Bagé
Brazil Banhado dos Pachecos
Brazil Tirecatinga / Utiariti
Paraguay Estancia Gran Siete
Paraguay Estancias Golondrina - El Trébol
Paraguay Fortín Toledo
Paraguay Laguna Ganzo
Paraguay Lagunas Saladas - Riacho Yacaré
Paraguay Morombi
Paraguay Parque Nacional Defensores del Chaco
Paraguay Parque Nacional Médanos del Chaco
Paraguay Parque Nacional Tinfunqué - Estero Patiño
Paraguay Paso Curuzú
Paraguay Pozo Hondo
Paraguay Ypané Medio
Bolivia Beni Biological Station Biosphere Reserve
Bolivia Otuquis Integrated Management Natural Area
Bolivia Lagunas Rogaguado y Ginebra
Bolivia Este de Río Mamoré
Bolivia Oeste de Río Mamoré
Brazil Nhumirim
Brazil Parque Nacional da Serra da Bodoquena e Entorno
Brazil Interflúvio dos Rios das Mortes e Araguaia
Brazil Caceres
Brazil Lizarda
Brazil Monumento Natural das Árvores Fossilizadas e Adjacências
Paraguay Estancia Estrella
Brazil Formoso do Araguaia
Brazil Curaçá
Brazil Raso da Catarina
Brazil Sento Sé / Campo Formoso

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Artificial/Terrestrial Arable Land marginal resident
Grassland Subtropical/Tropical Dry suitable resident
Grassland Subtropical/Tropical Seasonally Wet/Flooded suitable resident
Grassland Temperate suitable resident
Savanna Dry suitable resident
Shrubland Subtropical/Tropical Dry suitable resident
Shrubland Temperate suitable resident
Altitude 0 - 1650 m Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Agriculture & aquaculture Annual & perennial non-timber crops - Agro-industry farming Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Declines Medium Impact: 6
Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture Livestock farming & ranching - Agro-industry grazing, ranching or farming Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Declines Medium Impact: 6
Ecosystem degradation, Ecosystem conversion
Biological resource use Hunting & trapping terrestrial animals - Intentional use (species is the target) Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Declines Medium Impact: 6
Reduced reproductive success, Species mortality

Purpose Primary form used Life stage used Source Scale Level Timing
Food - human - - non-trivial recent
Medicine - human & veterinary - - non-trivial recent
Other household goods - - non-trivial recent
Pets/display animals, horticulture - - international non-trivial recent

Recommended citation
BirdLife International (2024) Species factsheet: Rhea americana. Downloaded from https://datazone.birdlife.org/species/factsheet/greater-rhea-rhea-americana on 04/03/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org on 04/03/2024.