Introduction
The Lesser Rhea, also known as Darwin’s Rhea, is a large flightless bird of South America. Its accepted scientific name is Rhea pennata. It belongs to the rhea family, Rheidae, and is the smaller of the two living species of Rhea. Three subspecies are generally recognised: Rhea pennata pennata, R. p. garleppi and R. p. tarapacensis.
Physical Description
The Lesser Rhea is a long-legged, long-necked bird with a compact body and broad wings. Adults are approximately 92.5–100 centimetres tall and commonly weigh about 15–25 kilograms. The plumage is mainly brown or grey-brown, with conspicuous white flecking that provides useful camouflage in steppe and scrub habitats.
The wings are relatively large for a flightless bird and help the rhea manoeuvre while running. It has three toes on each foot and strong legs adapted for fast movement over open ground. A claw on each wing can be used defensively.
Males and females are broadly similar, although females are generally duller and have less white spotting on the back. Juveniles are browner and lack the strongly developed white spotting of adults. Adult plumage develops gradually, reaching its typical appearance during the third or fourth year.
Range and Habitat
The Lesser Rhea is endemic to South America. Its range extends through Patagonia in Argentina and Chile and northwards into the Andean puna of northern Chile, western Bolivia, southern Peru and north-western Argentina. The distribution of the three recognised subspecies reflects this broad geographic range, with R. p. pennata associated mainly with Patagonia and the other two subspecies occurring in the northern Andean region.
It inhabits open landscapes, including Patagonian steppe, semi-desert, open shrubland, grassland and high-elevation puna. It generally avoids dense forest and favours areas where vegetation is low enough to provide visibility and space for running. In Patagonia, productive wet meadows and other seasonally or permanently moist areas, locally known as mallines, are important feeding and nesting habitats.
The species is resident rather than a long-distance migrant, although individuals may make local movements in response to food availability, weather and habitat conditions. It occurs from near sea level in parts of Patagonia to roughly 3,000 metres in the Andes.
Behaviour and Diet
Lesser Rheas are primarily diurnal and usually feed while walking through open country. They are mainly herbivorous, eating leaves, shoots, roots, fruits and seeds. Insects and other small animal matter may supplement the diet, particularly when available. Small stones are swallowed to help grind food in the muscular stomach.
The species is sociable outside the breeding season. Groups may contain a few birds or several dozen individuals, and flocking can improve vigilance against predators. Rheas often use their excellent eyesight to detect danger across open terrain. When alarmed, they run rapidly and may change direction sharply or weave through vegetation to confuse a pursuer.
Breeding involves polygyny and sequential polyandry. A male establishes a nesting area and courts several females. The females lay their eggs in a shared ground nest, after which the male incubates the eggs and raises the chicks. Incubation lasts approximately 35–40 days. The chicks are precocial and can walk soon after hatching, but the male protects and guides them for several weeks or months. Breeding dates vary across the species’ wide range, but activity commonly occurs during the warmer part of the year, including approximately September to January in parts of Patagonia.
Identification Tips
- Look for a large, flightless bird with a long neck, long powerful legs and a relatively small head.
- The brown or grey-brown plumage is marked with irregular white flecking, giving the bird a mottled appearance.
- The Lesser Rhea is smaller and more compact than the Greater Rhea, Rhea americana.
- It is most likely to be encountered in open steppe, shrubland, grassland or high Andean puna rather than dense woodland.
- When disturbed, it usually runs instead of flying, often with the neck held low and the wings helping it turn.
- Juveniles are browner and less heavily spotted than adults.
Conservation Status
The Lesser Rhea is currently classified as Least Concern on the IUCN Red List. This whole-species assessment reflects the current treatment of the northern Andean forms as subspecies of Rhea pennata. The taxonomic treatment has changed in recent years, and the former Puna Rhea concept was previously assessed separately by some authorities.
The global population has not been quantified reliably, and the species is not uniformly secure across its range. Documented pressures include hunting, collection of eggs, habitat conversion and degradation, disturbance, and the effects of livestock grazing. Local populations may also be affected by fencing, infrastructure and the loss or degradation of productive wet meadows used for feeding and nesting.
Important conservation measures include effective enforcement of hunting and egg-collection regulations, protection of steppe and puna habitats, management of productive wetland meadows, ecological monitoring and cooperation with local landholders and communities. Conservation planning should also recognise that the status of individual subspecies and regional populations may differ from the global assessment.
Frequently Asked Questions
Where does the Lesser Rhea live?
The species lives in open habitats across Argentina, Bolivia, Chile and Peru. It occurs in Patagonian steppe and shrubland as well as high-elevation Andean puna.
Is the Lesser Rhea able to fly?
No. The Lesser Rhea is flightless, but its large wings help it balance and manoeuvre while running.
What does the Lesser Rhea eat?
It eats mainly plant material, including leaves, shoots, roots, fruits and seeds. Insects and other small animal matter may also be taken, and swallowed stones help with digestion.
How does the Lesser Rhea raise its chicks?
Females lay their eggs in a nest prepared by the male. The male incubates the eggs and is responsible for protecting and guiding the chicks after they hatch.
How can the Lesser Rhea be distinguished from the Greater Rhea?
The Lesser Rhea is smaller and generally more compact than the Greater Rhea. Its plumage is brown or grey-brown with prominent white flecking, and it is associated mainly with Patagonian and Andean open habitats.
Is the Lesser Rhea endangered?
The species is currently listed as Least Concern globally, but hunting, egg collection and habitat degradation remain important regional threats. Some local populations may be declining even though the global assessment is not in a threatened category.
References
- BirdLife International. 2022. Red List status changes 2022.2. BirdLife International. Available at: https://forums.birdlife.org/wp-content/uploads/2022/10/Red_List_status_changes_2022.2.pdf (accessed 8 September 2026).
- BirdLife International and Handbook of the Birds of the World. 2024. Handbook of the Birds of the World and BirdLife International digital checklist of the birds of the world, version 9. BirdLife International and Lynx Edicions. Available at: https://datazone.birdlife.org/userfiles/file/Species/Taxonomy/HBW-BirdLife_Checklist_v9_Oct24.zip (accessed 8 September 2026).
- International Union for Conservation of Nature. 2022. Rhea pennata. The IUCN Red List of Threatened Species, species account 22678081. Available at: https://www.iucnredlist.org/species/22678081 (accessed 8 September 2026).
- Gill, F., Donsker, D. and Rasmussen, P., eds. 2026. IOC World Bird List, version 15.2. International Ornithologists’ Union. Available at: https://www.worldbirdnames.org/ (accessed 8 September 2026).
- Schmitt, F., Kirwan, G. M., Folch, A., Christie, D. A., Jutglar, F., Garcia, E. and Pantoja-Maggi, V. 2024. Lesser Rhea, Rhea pennata, version 2.1. In: G. M. Kirwan, ed., Birds of the World. Cornell Lab of Ornithology. https://doi.org/10.2173/bow.lesrhe2.02.1.
- Barri, F. R., Martella, M. B. and Navarro, J. L. 2009. Nest-site habitat selection by Lesser Rheas, Rhea pennata pennata, in northwestern Patagonia, Argentina. Journal of Ornithology 150(2): 511–514. https://doi.org/10.1007/s10336-009-0374-6.
- Barri, F. R., Roldán, N., Navarro, J. L. and Martella, M. B. 2012. Effects of group size, habitat and hunting risk on vigilance and foraging behaviour in the Lesser Rhea, Rhea pennata pennata. Emu 112(1): 67–70. https://doi.org/10.1071/MU10090.
- Pedrana, J., Bustamante, J., Travaini, A., Rodríguez, A., Zapata, S., Zanón Martínez, J. I. and Procopio, D. 2012. Environmental factors influencing the distribution of the Lesser Rhea, Rhea pennata pennata, in southern Patagonia. Emu 112(1): 18–26. https://doi.org/10.1071/MU11007.
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