# Rhea (*Rhea americana*)

The Rhea is a large bird that looks a bit like an ostrich but is native to South America! They are fast runners and can be found in open fields.

- **Category:** [Birds](https://www.snappit.app/explore/categories/bird)
- **Rarity:** Rare
- **Danger:** 2/5 · Low
- **Habitat:** Grasslands and savannas
- **Also known as:** American Rhea, Greater Rhea, Rheas

![Rhea](https://res.cloudinary.com/drieglelr/image/upload/v1771426290/objects/4655.jpg)

## Appearance

The Rhea is a large, flightless bird with shaggy, grey-brown feathers covering its body. It has a long neck, small head, and powerful long legs with three toes. Its wings are large, but mainly used for balance.

## Taxonomy

- **Kingdom:** Animalia
- **Phylum:** Chordata
- **Class:** Aves
- **Order:** Rheiformes
- **Family:** Rheidae
- **Genus:** Rhea

## Rhea, up close

The greater rhea (Rhea americana) is a large flightless bird of the grasslands and savannas of eastern and southern South America, and the continent’s largest bird. It eats mostly leaves, seeds and fruit, runs in sharp zig-zags with its long wings held out, and lives in groups outside the breeding season. Males build the nest, sit on eggs laid by several females and raise the striped chicks on their own.

Also called: Common rhea, Grey rhea, Ñandú, Ema (Portuguese), Nandu (German).

South America’s giant flightless runner, where the dads do all the parenting. Spin it, tap it, then test yourself.

### Special abilities

- **Zig-zag Sprint** (60+ km/h reported top speed): When chased, a rhea swerves hard from side to side, holding a wing out like a sail or rudder to turn. [4][7][2][15][13][20][21]
  - Hudson wrote that a hard-pressed rhea turns “frequently and rapidly at right angles”, leaving many a horse behind.
  - Darwin saw rheas set off with their wings spread, “like a vessel” making “all sail”.
  - Bird experts give a top speed of more than 60 km/h. We found no study that has timed one with instruments.
  - The smaller lesser rhea is said to be even faster, but it tires sooner.
  - Reported top speeds: Greater rhea 60+ km/h; Ostrich 70 km/h; Emu 48–50 km/h
- **Super Dad** (≈42 days on the nest, alone): One male sits on eggs laid by several females, then guards the striped chicks on his own for months. [22][18][23][4][2][7]
  - He stays with the eggs for about 42 days and sits on them up to 97.5% of the time, slipping away only in the hottest hours.
  - Most nests hold 20–30 eggs. Very big clutches, over 30–35 eggs, hatch worse.
  - After hatching he guards the chicks for 4–6 months and charges at anything that comes too close, even horses and people.
  - It is hard work: fewer than 20% of males try to nest in a season.
  - Eggs in one rhea nest: Most nests (Argentina) 20–30; Biggest counted 56; Darwin’s nests, 1833 22–27
- **Boom Call** (749 booms in 8 days): Rheas are mostly quiet, but in the breeding season males give a deep booming call that is hard to pin down. [11][8][4][7][10][24]
  - One group of rheas at a zoo in Mato Grosso, Brazil, gave 749 booming calls in 8 days, most in the first 4 hours after sunrise and some at night.
  - Hudson described the sound as a “ventriloquial” booming. Darwin first thought it came from a wild beast.
  - The rhea’s voice box (syrinx) is more complex than in other ratites.
  - The German nature group NABU says the call sounds roughly like “nan-du”.
- **Three-Toed Runner** (3 toes per foot): Long legs and three toes make the rhea a born runner. Ostriches, the only two-toed birds, run on just two. [2][25][13][4]
  - Rheas, like emus, have three toes on each foot and no hind toe.
  - Ostriches are the only birds with just two toes.
  - Built for open grassland: Hudson noted that rheas sometimes trip when tall grass is tied together by twining plants.
  - Toes per foot: Greater rhea 3; Emu 3; Ostrich 2
- **Wing Show** (2–12 females courted by one male): To win a harem, a male spreads his long wings, shakes his neck and runs at the females. [2][12][26][4]
  - He courts 2–12 females, who all lay their eggs in his nest.
  - In a Brazilian study, harem males made the open-wings display about 13–15 times an hour.
  - Courtship peaks while the harem is forming, and males drive rival males away.
  - The same wings-out pose becomes a threat when a dad charges an intruder.
- **Lookout Crew** (2–20 birds in a group; still debated): Rheas often feed in groups. Each bird can then spend less time on lookout and more time eating. [27][5][6][28][29]
  - Rheas feed alone or in groups of 2–20. A typical group in the Argentine pampas had about 8 birds.
  - A rhea feeding alone spends more time watching and less time eating than one in a group.
  - Whether bigger groups spot predators sooner is still argued. One study found the group as a whole was not more watchful, while a computer model suggests group scanning could help.
  - Encyclopedias say rheas often graze alongside deer and other plant-eaters, but we found no study that has measured this.
- **Lie Low** (0 heads in the sand): Instead of running, a rhea may crouch flat in tall grass and keep still until danger has passed. [4][7][13]
  - Hudson found hiding rheas lie so close that they “will not rise until almost trodden on”.
  - Darwin watched rheas squat out of sight in a bed of tall rushes.
  - When an eagle or a caracara flies over, a dad crouches and gives a loud snorting cry, and his chicks dash under his wings.
  - Rheas never bury their heads in sand. Even the ostrich version of that story is a myth.

### Body parts

- **Beak** [1][2][3]
  - Mostly a plant-eater. In grassland in Argentina, rheas preferred broad-leaved plants, especially clover-like legumes, over grasses.
  - It also picks up seeds, fruit, roots and insects, and now and then a small animal such as a lizard.
  - It swallows small stones, which help grind up tough food in the stomach.
- **Eyes** [4][5][6][7]
  - Standing tall on open plains, a rhea can see a long way over the grass.
  - A rhea feeding alone spends more time looking up and less time eating than one in a group.
  - Darwin found lesser rheas so wary that they seemed to spot people before people could make them out.
- **Voice** (749 booms in 8 days) [8][9][10][11]
  - Only males boom, as part of courtship. Adults of both sexes hiss when threatened.
  - The voice box (syrinx) is more complex than in other ratites, and adult males have a partly bony piece inside it.
  - Chicks whistle a lot, but their calls fade and stop by about 7 weeks old.
- **Wings** [2][4][12]
  - Unusually long for a flightless bird. Rheas hold them out like rudders to dodge and to keep their balance while running.
  - A hard-pressed rhea often raises one wing “like a great sail” and turns sharply.
  - Males spread them wide to court females, and to charge at anything that comes near their chicks.
  - Chicks shelter under their dad’s wings when a hawk flies over.
- **Feet** (3 toes per foot) [2][13][14][15]
  - Three toes on each foot and no hind toe. Ostriches are the only birds with just two.
  - Broad, band-like scales run down the front of the leg. Lesser rheas have small net-like scales instead, and feathers on the upper leg.
  - Long, strong legs carry it across open country at more than 60 km/h.
- **Feathers** [4][2][7]
  - Loose, shaggy, mostly grey plumage. The naturalist W. H. Hudson thought it matched the haze on the plains, which made rheas hard to see.
  - No showy tail plumes like an ostrich.
  - In the breeding season males get a dark collar at the base of the neck. Males are usually bigger and darker than females.
- **Gut** (≈62 h for seeds to pass through) [16]
  - In captive rheas, food took about 62 hours on average to pass through, so seeds can travel a long way before they are dropped.
  - Some seeds sprouted better or faster after the trip. Others were ground up and destroyed.
  - Scientists warn that fewer rheas could mean fewer seeds carried far, which may affect plants that rely on them.
- **Nest** (20–30 eggs in most nests) [17][18][19][4]
  - A shallow scrape on the ground. Males often choose spots hidden by shrubs.
  - Several females lay in the same nest. Most nests hold 20–30 eggs, and the most counted in one Argentine study was 56.
  - Each egg weighs about 440–620 g and is golden-yellow when fresh, fading towards white.
  - Tegu lizards sometimes sneak away with an egg while the dad stays put.

### Stats

| Stat | Value | Notes |
|---|---|---|
| Height | Up to 1.7 m | standing tall; males are usually bigger; An ostrich can reach 2.7 m [3][24][2][13] |
| Weight | 15–36 kg | adults; South America’s heaviest bird; An ostrich weighs 90–130 kg [2][3][34][13] |
| Top speed | 60+ km/h | reported, while zig-zagging [15][13] |
| Eggs per nest | 20–30 | usually, from several mums; up to 56 counted [18] |
| Egg weight | 440–620 g | golden-yellow when fresh; About the weight of an emu egg [19][4][20] |
| Dad on the nest | ≈42 days | sitting up to 97.5% of the time [22] |
| Chick care | 4–6 months | by dad alone [22] |
| Seed trip | ≈62 h | for food to pass through (captive rheas) [16] |
| Group size | 2–20 | birds; a typical group has about 8 [27] |
| Lifespan | 13+ yrs | known; the maximum is not yet established [35] |

### Photos

- [Greater rhea in Encontro das Águas State Park, Pantanal, Brazil](https://commons.wikimedia.org/wiki/File:179_Greater_rhea_in_Encontro_das_%C3%81guas_State_Park_Photo_by_Giles_Laurent.jpg) (photo: Giles Laurent, CC BY-SA 4.0)
- [Greater rhea in the Pantanal, Brazil](https://commons.wikimedia.org/wiki/File:Greater_rhea_(Rhea_americana).JPG) (photo: Charles J. Sharp, CC BY-SA 4.0)
- [The head: big eyes on a long, slim neck](https://commons.wikimedia.org/wiki/File:Greater_rhea_close_up.jpg) (photo: Michael Palmer, CC BY-SA 4.0)
- [A dad with a big group of chicks, Brasília](https://commons.wikimedia.org/wiki/File:2014_-_Pal%C3%A1cio_do_Jaburu_(15757985506).jpg) (photo: Romério Cunha (Palácio do Jaburu), CC BY 2.0)
- [A striped chick resting in the grass](https://commons.wikimedia.org/wiki/File:Greater_rhea_chick_lying_in_grass_-_DPLA_-_f918309bb48edd47bf1b876887bcf3bb.jpg) (photo: Warren Garst (Colorado State University Libraries), CC BY-SA 4.0)
- [A clutch of eggs in a nest scrape](https://commons.wikimedia.org/wiki/File:Rhea_americana_clutch.jpg) (photo: J. Rzadkowski, CC BY-SA 3.0 DE)
- [A white rhea with a grey one near Utecht, Germany](https://commons.wikimedia.org/wiki/File:Nandu_Wei%C3%9Fe_Morphe.jpg) (photo: Gregor Rom, CC BY-SA 4.0)
- [Wild rheas in winter in Mecklenburg-Vorpommern, Germany](https://commons.wikimedia.org/wiki/File:Nandus_(Rhea_americana)_in_Rieps%2C_Mecklenburg-Vorpommern_20130224_0297a.jpg) (photo: Sabrina Vincent, CC BY-SA 4.0)
- [Darwin’s rhea (lesser rhea) in Torres del Paine, Chile](https://commons.wikimedia.org/wiki/File:Rhea_pennata%2C_Torres_Del_Paine%2C_Patagonia_1.jpg) (photo: Ian Rutherford, CC BY 2.0)

### Questions

- **How fast can a rhea run?** Bird experts say rheas can run at more than 60 km/h, though we found no study that has timed one with instruments. When chased they swerve in zig-zags, holding one wing up like a sail to steer. [15][4][2]
- **What is the difference between a rhea and an ostrich?** Rheas live in South America, ostriches in Africa. A greater rhea stands up to about 1.7 m and weighs 15–36 kg, while an ostrich can reach 2.7 m and 90–130 kg. Rheas have three toes, ostriches two, and in rheas only the dad sits on the eggs. [2][3][13][22]
- **Do rheas bury their heads in the sand?** No. A frightened rhea runs off in zig-zags or crouches flat in tall grass and keeps still. The head-in-the-sand story is an old ostrich myth, and ostriches don’t do it either. [4][7][13]
- **Do male rheas really raise the chicks alone?** Yes. Several females lay in one male’s nest, then leave. He sits on the eggs for about 6 weeks and guards the striped chicks for 4–6 months. A young male sometimes helps by sitting on a second nest, and on farms males even adopt chicks that aren’t theirs. [22][23][12][48]
- **Are rheas endangered?** The greater rhea is listed as Near Threatened and is declining, mainly because grassland is being turned into farmland and because it is hunted. Its smaller cousin, the lesser rhea, is Least Concern worldwide but also declining. [30][32]
- **Can rheas fly?** No. Rheas are flightless, but their wings are unusually long for a flightless bird. They use them to steer and balance when running, and in courtship displays. [2]
- **Why are there wild rheas in Germany?** In 2000, 7–12 rheas escaped from an enclosure near Lübeck. They survived the winters and bred, and by 2017 there were about 250. Several hundred now live between Lake Ratzeburg and the Schaalsee, and they have been hunted since 2019. [39][24]
- **Why is it called a rhea?** Scientists named the genus Rhea, probably after Rhea, the mother of Zeus in Greek myth. In the Guaraní language of South America the bird is called ñandú. [49][4]

### Rhea myths and facts

Tap Myth or Fact for each claim, then check the answer.

- "Rheas are a kind of ostrich." **Myth!** They look alike and early settlers called rheas “ostriches”, but rheas are a separate family from South America with three toes, not two. DNA studies show the ostrich line split off first, and their flying ancestors lost flight more than once. [4][2][13][36][37][38]
- "Rheas bury their heads in the sand when they are scared." **Myth!** A frightened rhea zig-zags away or crouches flat in tall grass. The head-in-the-sand story is an old ostrich myth, and ostriches don’t do it either. [4][7][13]
- "Rhea dads sit on the eggs and raise the chicks on their own." **Fact!** The male sits on the eggs for about 6 weeks and guards the chicks for 4–6 months. The females don’t help. [22][19]
- "All the eggs in a rhea nest come from one mother." **Myth!** Several females lay in the same nest, then move on to lay for other males. That is why one nest can hold 20–30 eggs or more. [23][12][18]
- "Rheas can swim." **Fact!** Darwin saw rheas swim across the Santa Cruz river in Patagonia, about 400 yards (370 m) wide, and a shipmate saw them swim about 200 yards between islands. [7]
- "Rheas are silent birds." **Myth!** Adults are mostly quiet, but males boom in the breeding season (one zoo group gave 749 booms in 8 days), adults hiss when threatened and chicks whistle. [11][8][9]
- "Wild rheas live in Germany." **Fact!** In 2000, 7–12 rheas escaped from an enclosure near Lübeck. By 2017 there were about 250, and several hundred now roam fields in northern Germany. [39][24]
- "Some people see a rhea in the night sky." **Fact!** The Mocoví people of the Argentine Chaco see a rhea in the dark patches of the Milky Way, with its head at the Coalsack beside the Southern Cross. [40]

### Rhea records

Superlatives and record holders, each checked against its source.

- Largest bird in South America: Greater rhea, up to 1.7 m (and up to about 36 kg; the continent’s tallest and heaviest bird) [33][2][3][34]
- Biggest nest in an Argentine study: One rhea dad, 56 eggs (most nests held 20–30) [18]
- Booming marathon: A rhea group at a zoo in Mato Grosso, Brazil, 749 booms (recorded in 8 days) [11]
- Oldest rhea pictures: Rock paintings in Piauí, Brazil, 12,000–8,000 BC (as reported by Birds of the World) [33]
- A bird named after Darwin: Rhea darwinii (now Rhea pennata), 1837 (named by John Gould from a bird Darwin’s crew had already cooked) [14][7]

### Rhea from egg to adult

From a golden egg to a grown-up rhea in about two years, with dad in charge of the first months.

- **Late winter**: Flocks split up. Males chase rivals, twist necks in fights and start booming to attract females. [4][27]
- **Spring**: Harem and nest. A male courts 2–12 females with wing displays and scrapes a nest in a hidden spot. [2][12][17]
- **Days 1–10**: Egg drop-off. Each female lays an egg about every 2 days in the dad’s nest. Laying lasts about 8–9 days. [19]
- **≈6 weeks**: Dad on duty. He sits on the eggs up to 97.5% of the time and leaves only in the hottest hours. Full incubation takes about 36–40 days. [22][19][35]
- **Hatch day**: All at once. The chicks hatch within hours of each other. In one nest, 9 chicks hatched in under 5 hours. [19]
- **First weeks**: Whistling chicks. Striped chicks whistle to keep in touch and go quiet by about 7 weeks. When a hawk flies over they run under dad’s wings, and one brood was even seen hiding in an armadillo burrow. [8][4][34]
- **4–7 months**: Leaving dad. Dad guards the chicks for 4–6 months, sometimes up to 7. Their stripes are gone by about 5 months. [22][19][12]
- **≈2 years**: Grown up. Young rheas roam in groups until they are about 2 years old and ready to breed. [12][3]
- **13+ years**: A long life. Rheas are known to live at least 13 years. Nobody knows yet how long they can live. [35]

### Rhea vs ostrich vs emu

Three big flightless runners on three continents. Check the toes and who sits on the eggs.

| | Greater rhea | Ostrich | Emu |
|---|---|---|---|
| Lives in [2][41][21] | South America | Africa | Australia |
| Height [3][13][20] | Up to 1.7 m | Up to 2.7 m | 1.5–1.9 m |
| Weight [2][3][13][20] | 15–36 kg | 90–130 kg | 30–55 kg |
| Toes per foot [2][13][25] | 3 | 2 | 3 |
| Wings [2][41][21] | Long; used like rudders | Large; used like rudders and to keep cool | Tiny; under 20 cm |
| Top speed (reported) [15][13][20][21] | 60+ km/h | 70 km/h | 48–50 km/h |
| Egg weight [19][13][20] | 440–620 g | ≈1,500 g | 450–650 g |
| Who sits on the eggs [22][13][21] | Dad alone | Main hen by day, male by night | Dad alone |
| Incubation [35][19][13][21] | ≈36–40 days | 42–46 days | ≈56 days |
| IUCN status [30][42] | Near Threatened | Least Concern | Least Concern |

All three are ratites, but DNA shows they are not each other’s closest relatives: the ostrich line split off first.

### Are rheas endangered?

Not yet, but the greater rhea is slowly losing ground as South America’s grasslands turn into farmland.

- **IUCN Red List:** Near Threatened (NT) (Population decreasing). Still found across a huge range, but suspected to be declining by roughly 20–29% over three generations (about 33 years), mainly because of habitat loss and hunting. It has disappeared from Ceará and Rio Grande do Norte in north-east Brazil, where reintroduced birds now live in parts. [30]
- IUCN Red List, assessed 2022 (BirdLife International)
- **Threat: Grassland turned to crops** (51% vs <5%): In one study in the Argentine pampas, rheas used 51% of a grassland site but less than 5% of a cropland site, and were several times more common in grassland. [43][30]
- **Threat: Hunting and egg collecting** (50,000+): Skins traded in 1980 alone. Rheas are still hunted for meat, eggs are collected for food, and feathers end up as dusters. [30][2]
- **Threat: Farm chemicals** (≈4×): Feathers of rheas living among intensive crops held about four times more long-lasting pollutants than those of rheas on cattle ranches. [44]
- **Threat: Fences**: Rheas don’t jump fences (they squeeze underneath), so fencing can block their movements. [33]
- **Helping: Grazing land and grassland**: Rheas do best where pastures and native grassland remain. Experts call for keeping these habitats and linking patches with corridors. [45][30]
- **Helping: Training for the wild**: Captive-bred rheas learn to fear predators before release. Trained birds become more cautious, and trained females wander less. [46][47]
- **Helping: Trade rules**: International trade is controlled under CITES Appendix II, so exports need permits. [30][2]
- **Lesser rhea (Darwin’s rhea)** (LC): Least Concern worldwide (2022) but declining, mainly from hunting, egg collecting and habitat loss. It is listed as Critically Endangered in Peru, Vulnerable in Argentina and Endangered in Chile. [32]

### Darwin and the rhea

On the voyage of the Beagle, Charles Darwin chased a rumour about a second, smaller rhea, and almost lost it to the cooking pot.

- **Aug 1833**: A rumour at the Río Negro. Gauchos told Darwin about a rare, smaller rhea, the “Avestruz Petise”, with shorter legs feathered further down. [7][14]
- **Sep–Oct 1833**: Counting eggs. Near Bahía Blanca he found nests with 22, 22, 22 and 27 eggs, and learned that several females lay in one nest while the male hatches them. [7]
- **Dec 1833–Jan 1834**: Oops, dinner. At Port Desire, a shipmate, Mr Martens, shot a rhea. Darwin took it for a young common rhea, and it was cooked and eaten before he remembered the rumour. [7][14]
- **Back in London**: Rebuilt from leftovers. The head, neck, legs, wings, many feathers and much of the skin had been kept, and a nearly complete specimen was put together in London. [7][14]
- **1834**: A French name first. The French naturalist Alcide d’Orbigny, who had searched for the bird in vain, proposed the name Rhea pennata. [14][15]
- **1837**: Named after Darwin. John Gould described the bird as Rhea darwinii. Darwin noted that the two rheas replace each other around the Río Negro. [14][7]
- **Today**: Lesser rhea. Because d’Orbigny’s name came first, scientists now call it Rhea pennata, the lesser or Darwin’s rhea. It lives in Patagonia and the high Andes. [15][32]

### Rhea signals

- Deep booming: A male calling during the breeding season, mostly in the first hours after sunrise. [8][11]
- Wings out, walking beside a female: Courtship display. [12][2]
- Hissing with the beak open: A threat: back off. [9][8]
- Wings spread, running straight at you: A dad defending his chicks. Keep well away. [4][2]
- Two males with necks twisted together: A fight over females, most common in winter and spring. [4][27]
- Head up, looking around: On lookout duty. Rheas alone do this more than rheas in groups. [5][6]
- Crouched flat in tall grass: Hiding from danger. [4][7]
- Soft whistles from chicks: Chicks keeping in touch with each other and their dad. [8]

### Looks

- **Greater rhea**: Shaggy grey plumage with black at the base of the neck and between the shoulders, and whitish underparts. Breeding males get a darker collar. (Near Threatened · decreasing) [4][2][30]
- **White (leucistic) rhea**: The same species with white feathers: most of the usual grey colour is missing. White rheas are rare. They turn up in zoos and on farms, and one was photographed in the wild flock in northern Germany. (A rare colour form, not a separate species)
- **Darwin’s rhea (lesser rhea)**: A separate, smaller species, Rhea pennata, about 1 m tall: brown feathers tipped with white, feathers halfway down the legs and small net-like leg scales. (Least Concern · decreasing) [14][31][15][32]
- **Dad with chicks**: Chicks are grey-brown with dark stripes along the back, which are gone by about 5 months. A dad is often seen leading 20 or more. (Dad alone looks after them for 4–6 months) [12][33][22]

### Rhea quiz

1. Which continent is the greater rhea’s native home? **South America.** Greater rheas are native to the grasslands and savannas of eastern and southern South America. [2]
2. Who sits on the eggs in a rhea nest? **The father.** The male sits on the eggs for about 6 weeks and then guards the chicks alone. [22]
3. How many toes does a rhea have on each foot? **3.** Rheas have three toes. Ostriches are the only birds with two. [2][13]
4. How many eggs are in most rhea nests? **20–30.** Several females lay in one nest, so most nests hold 20–30 eggs. [18]
5. What does a running rhea do with its long wings? **Holds them out to steer and balance.** Rheas can’t fly, but they hold their wings out like rudders to dodge and keep their balance. [2]
6. What does a scared rhea do instead of burying its head? **Crouches flat in tall grass.** Rheas zig-zag away or crouch low in tall grass. No bird buries its head in the sand. [4][13]
7. How long does a rhea dad guard his chicks? **4–6 months.** In a study in Argentina, dads cared for their chicks for 4–6 months. [22]
8. Which famous naturalist ate a new kind of rhea by mistake? **Charles Darwin.** Darwin’s crew cooked the bird before he realised it was the rare lesser rhea. It was later named after him. [7][14]
9. What is the greater rhea’s IUCN status? **Near Threatened.** It is Near Threatened and declining, mainly because of habitat loss and hunting. [30]
10. In which country did escaped rheas start a wild population in 2000? **Germany.** A few rheas escaped near Lübeck, and several hundred now live wild in northern Germany. [39][24]
11. What sound do male rheas make in the breeding season? **A deep boom.** Males give a deep booming call. One zoo group made 749 booms in 8 days. [8][11]
12. About how long did food take to pass through a captive rhea’s gut? **About 62 hours.** About 62 hours on average, long enough for seeds to be carried far away. [16]

### Sources (checked 2026-10-16)

1. [Comparatore V, Yagueddú C (2016). Diet preference and density of the Greater Rhea (Rhea americana) in grasslands of the Flooding Pampa, Argentina. Revista Brasileira de Ornitologia 24(1):13–20.](https://doi.org/10.1007/BF03544323)
2. [Smithsonian's National Zoo and Conservation Biology Institute. Greater rhea.](https://nationalzoo.si.edu/animals/greater-rhea)
3. [Hodges K (author), Animal Diversity Web. Rhea americana (greater rhea). University of Michigan Museum of Zoology.](https://animaldiversity.org/accounts/Rhea_americana/)
4. [Hudson WH (1920). Birds of La Plata, vol. 2, pp. 230–236 (Common Rhea; Darwin's Rhea). London: J. M. Dent & Sons.](https://archive.org/details/birdsoflaplata02huds)
5. [Reboreda JC, Fernández GJ (1997). Sexual, seasonal and group size differences in the allocation of time between vigilance and feeding in the Greater Rhea, Rhea americana. Ethology 103(3):198–207.](https://doi.org/10.1111/j.1439-0310.1997.tb00116.x)
6. [Fernández GJ, Capurro AF, Reboreda JC (2003). Effect of group size on individual and collective vigilance in Greater Rheas. Ethology 109(5):413–425.](https://doi.org/10.1046/j.1439-0310.2003.00887.x)
7. [Darwin C (1845). Journal of Researches into the Natural History and Geology of the Countries Visited during the Voyage of H.M.S. Beagle, 2nd ed., ch. V. (Project Gutenberg eBook #944, The Voyage of the Beagle.)](https://www.gutenberg.org/ebooks/944)
8. [Beaver PW (1978). Ontogeny of vocalization in the Greater Rhea. The Auk 95(2):382–388.](https://doi.org/10.1093/auk/95.2.382)
9. [Thys B, Eens M (2025). Avian hissing sounds: occurrence, mechanism, ontogeny, function and phylogeny. Royal Society Open Science 12:251298.](https://doi.org/10.1098/rsos.251298)
10. [Picasso MBJ, Carril J (2013). The peculiar syrinx of Rhea americana (Greater Rhea, Palaeognathae). Vertebrate Zoology 63(3):321–327.](https://doi.org/10.3897/vz.63.e31454)
11. [Pérez-Granados C, Schuchmann K-L (2021). Vocalisations of the Greater Rhea (Rhea americana): an allegedly silent ratite. Bioacoustics 30(5):564–574.](https://doi.org/10.1080/09524622.2020.1821399)
12. [Codenotti TL, Alvarez F (1997). Cooperative breeding between males in the Greater Rhea Rhea americana. Ibis 139(3):568–571.](https://doi.org/10.1111/j.1474-919X.1997.tb04675.x)
13. [San Diego Zoo Wildlife Alliance. Ostrich.](https://animals.sandiegozoo.org/animals/ostrich)
14. [Gould J (descriptions), Darwin C (ed.) (1841). The Zoology of the Voyage of H.M.S. Beagle, Part 3: Birds, pp. 120–125, pl. 47 (Rhea Darwinii). London: Smith, Elder & Co.](https://archive.org/details/zoologyofvoyageo03darw)
15. [Schmitt F, Kirwan GM, Folch A, Christie DA, Jutglar F, Garcia E, Pantoja-Maggi V (2024). Lesser Rhea (Rhea pennata), version 2.1. Birds of the World (Cornell Lab of Ornithology).](https://doi.org/10.2173/bow.lesrhe2.02.1)
16. [Jacques CLB, Mariano V, Christianini AV (2025). Gut-passage time and the role of the Greater Rhea (Rhea americana) influencing seed dispersal and predation in Neotropical grasslands and savannas. Emu 125(1):60–72.](https://doi.org/10.1080/01584197.2024.2442343)
17. [Fernández GJ, Reboreda JC (2002). Nest-site selection by male Greater Rheas. Journal of Field Ornithology 73(2):166–173.](https://doi.org/10.1648/0273-8570-73.2.166)
18. [Fernández GJ, Reboreda JC (1998). Effects of clutch size and timing of breeding on reproductive success of Greater Rheas. The Auk 115(2):340–348.](https://doi.org/10.2307/4089192)
19. [Codenotti TL (1997). Fenología reproductiva y biometría de nidos, huevos y pollos del Ñandú, Rhea americana, en Rio Grande do Sul, Brasil. El Hornero 14:211–223.](https://doi.org/10.56178/eh.v14i4.966)
20. [San Diego Zoo Wildlife Alliance. Emu.](https://animals.sandiegozoo.org/animals/emu)
21. [Smithsonian's National Zoo and Conservation Biology Institute. Emu.](https://nationalzoo.si.edu/animals/emu)
22. [Fernández GJ, Reboreda JC (2003). Male parental care in Greater Rheas (Rhea americana) in Argentina. The Auk 120(2):418–428.](https://doi.org/10.1093/auk/120.2.418)
23. [Fernández GJ, Reboreda JC (2007). Costs of large communal clutches for male and female Greater Rheas Rhea americana. Ibis 149(2):215–222.](https://doi.org/10.1111/j.1474-919X.2006.00629.x)
24. [NABU (Naturschutzbund Deutschland). Nandu – Steckbrief.](https://www.nabu.de/tiere-und-pflanzen/voegel/portraets/nandu/)
25. [Australian Museum. Emu.](https://australian.museum/learn/animals/birds/emu/)
26. [Codenotti TL, Alvarez F (2001). Mating behavior of the male Greater Rhea. The Wilson Bulletin 113(1):85–89.](https://doi.org/10.1676/0043-5643(2001)113[0085:MBOTMG]2.0.CO;2)
27. [Carro ME, Fernández GJ (2008). Seasonal variation in social organisation and diurnal activity budget of the Greater Rhea (Rhea americana) in the Argentinean pampas. Emu 108(2):167–173.](https://doi.org/10.1071/MU07052)
28. [Carro ME, Fernández GJ (2009). Scanning pattern of greater rheas, Rhea americana: collective vigilance would increase the probability of detecting a predator. Journal of Ethology 27(3):429–436.](https://doi.org/10.1007/s10164-008-0137-5)
29. [Grzimek's Student Animal Life Resource. Rheas: Rheidae. Via Encyclopedia.com.](https://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/rheas-rheidae)
30. [BirdLife International (2022). Rhea americana. The IUCN Red List of Threatened Species 2022: e.T22678073A219615764.](https://doi.org/10.2305/IUCN.UK.2022-2.RLTS.T22678073A219615764.en)
31. [Animal Diversity Web. Pterocnemia pennata (lesser rhea / Darwin's rhea).](https://animaldiversity.org/accounts/Pterocnemia_pennata/)
32. [BirdLife International (2022). Rhea pennata. The IUCN Red List of Threatened Species 2022 (Least Concern). BirdLife DataZone factsheet.](https://datazone.birdlife.org/species/factsheet/lesser-rhea-rhea-pennata)
33. [Kirwan GM, Korthals A, Hodes CE (2021). Greater Rhea (Rhea americana), version 2.0. Birds of the World (Cornell Lab of Ornithology).](https://doi.org/10.2173/bow.grerhe1.02)
34. [Treboux GO, Lozano D, Vega GG (2026). Primera observación de uso de cuevas como refugios de pichones de Ñandú (Rhea americana) en el Parque Nacional El Palmar, Entre Ríos, Argentina. Nuestras Aves 71.](https://doi.org/10.56178/na.v71i.1183)
35. [AnAge: The Animal Ageing and Longevity Database. Rhea americana (greater rhea).](https://genomics.senescence.info/species/entry.php?species=Rhea_americana)
36. [Mitchell KJ, Llamas B, Soubrier J, Rawlence NJ, Worthy TH, Wood J, Lee MSY, Cooper A (2014). Ancient DNA reveals elephant birds and kiwi are sister taxa and clarifies ratite bird evolution. Science 344(6186):898–900.](https://doi.org/10.1126/science.1251981)
37. [Sackton TB, Grayson P, Cloutier A, Hu Z, Liu JS, Wheeler NE, Gardner PP, Clarke JA, Baker AJ, Clamp M, Edwards SV (2019). Convergent regulatory evolution and loss of flight in paleognathous birds. Science 364(6435):74–78.](https://doi.org/10.1126/science.aat7244)
38. [Yonezawa T, Segawa T, Mori H, et al. (2017). Phylogenomics and morphology of extinct paleognaths reveal the origin and evolution of the ratites. Current Biology 27(1):68–77.](https://doi.org/10.1016/j.cub.2016.10.029)
39. [Lèche A, Gismondi E, Martella MB, Korthals A, Krone O, Navarro JL (2025). Persistent organic pollutants detected in feathers of feral Greater Rheas in Northern Germany: a comparative analysis with native populations of Argentina. Journal of Ornithology 166(4):1117–1121.](https://doi.org/10.1007/s10336-025-02289-x)
40. [Mudrik A (2017). "El Ñandú" en el cielo: etnoastronomía de gringos, criollos e indígenas y las representaciones celestes de Rhea americana en el sur del Chaco argentino. El Hornero 32(1):7–17.](https://doi.org/10.56178/eh.v32i1.527)
41. [Smithsonian's National Zoo and Conservation Biology Institute. Ostrich.](https://nationalzoo.si.edu/animals/ostrich)
42. [IUCN Red List categories via GBIF's IUCN Red List checklist dataset: Struthio camelus (Least Concern) and Dromaius novaehollandiae (Least Concern).](https://www.gbif.org/dataset/19491596-35ae-4a91-9a98-85cf505f1bd3)
43. [Giordano PF, Bellis LM, Navarro JL, Martella MB (2008). Abundance and spatial distribution of Greater Rhea Rhea americana in two sites on the pampas grasslands with different land use. Bird Conservation International 18(1):63–70.](https://doi.org/10.1017/S0959270908000075)
44. [Lèche A, Gismondi E, Martella MB, Navarro JL (2021). First assessment of persistent organic pollutants in the Greater rhea (Rhea americana), a near-threatened flightless herbivorous bird of the Pampas grasslands. Environmental Science and Pollution Research 28:27681–27693.](https://doi.org/10.1007/s11356-021-12614-5)
45. [Pedrana J, Bernad L, Maceira NO, Isacch JP (2015). Conflict between the Greater Rhea and humans in agricultural landscapes: implications for conservation of the last large herbivore of the southern Pampas. Emu 115(4):335–344.](https://doi.org/10.1071/MU15049)
46. [Azevedo CS, Young RJ (2006). Shyness and boldness in greater rheas Rhea americana: the effects of antipredator training on the personality of the birds. Revista Brasileira de Zoologia 23(1):202–210.](https://doi.org/10.1590/S0101-81752006000100012)
47. [Vera Cortez M, Navarro JL, Martella MB (2018). Effect of antipredator training on spatial behaviour of male and female Greater Rheas Rhea americana reintroduced into the wild. Acta Ornithologica 53(1):81–90.](https://doi.org/10.3161/00016454AO2018.53.1.008)
48. [Barri FR, Navarro JL, Maceira NO, Martella MB (2005). Rearing Greater Rhea (Rhea americana) chicks: is adoption more effective than the artificial intensive system? British Poultry Science 46(1):22–25.](https://doi.org/10.1080/00071660400023888)
49. [Merriam-Webster Dictionary. rhea (noun): etymology.](https://www.merriam-webster.com/dictionary/rhea)

## Measurements & details

- **Length:** 125-150 cm
- **Wingspan:** 150-180 cm
- **Weight:** 15-36 kg
- **Lifespan:** 10-15 years
- **Speed:** 60 km/h
- **Clutch Size:** 20-30
- **Incubation:** 35-40 days
- **Migration Distance:** 0 km

## Diet & Feeding

Rheas are omnivores. They mostly eat plants, seeds and fruits, plus insects and, now and then, a small animal like a lizard!

- **Age differences:** Young chicks eat more insects for protein, adults are more herbivorous.
- **Primary Foods:** Broad-leaved plants, Clover-like legumes, Seeds, Fruits, Insects
- **Foraging Method:** Foraging

## Ecological connections

- **Eaten by:** Puma (*Puma concolor*) — Can prey on adult rheas and chicks.
- **Eaten by:** [Jaguar](https://www.snappit.app/explore/jaguar) (*Panthera onca*) — Can also prey on rheas.
- **Eats:** South American Locust (*Schistocerca cancellata*) — A common insect prey item.
- **Eats:** American Nightshade (*Solanum americanum*) — Consumes its berries and leaves.

## Traits

- [Wildlife](https://www.snappit.app/explore/traits/wildlife): Wildlife encompasses all undomesticated animal and plant life existing in their natural habitats.
- [Feathered](https://www.snappit.app/explore/traits/feathered): Feathered describes animals, primarily birds, possessing a covering of feathers.
- [Social](https://www.snappit.app/explore/traits/social): Social animals live in organized groups, cooperating for survival benefits such as foraging, defense, and raising offspring.
- [Grassland](https://www.snappit.app/explore/traits/grassland): Grassland habitats are terrestrial biomes dominated by grasses and herbaceous plants, supporting a variety of grazing animals.
- [Herbivorous](https://www.snappit.app/explore/traits/herbivorous): This trait characterizes organisms whose diet consists entirely or primarily of plant material.
- [Speedster](https://www.snappit.app/explore/traits/speedster): This trait identifies organisms that exhibit exceptional swiftness in movement for hunting, escape, or travel.

## Collections

- [Birds](https://www.snappit.app/explore/collections/birds)

## Safety

**Danger:** 2/5 · Low

Watch quietly from a distance and never try to feed or chase wild animals. A dad with chicks may charge at anything that comes too close.

## Frequently Asked Questions

### How to identify Rhea?

Compare the silhouette, bill shape, tail length, wing bars and markings around the eyes. The same small brown bird at your feeder can look quite different in breeding plumage, winter plumage or its first year. Bird Identifier: upload a photo and compare the visible details.

### How long is Rhea?

125-150 cm

### What is Rhea's wingspan?

150-180 cm

### How much does Rhea weigh?

15-36 kg

### How long does Rhea live?

10-15 years

### What does Rhea eat?

Rheas are omnivores. They mostly eat plants, seeds and fruits, plus insects and, now and then, a small animal like a lizard!

### Where is Rhea usually found?

Grasslands and savannas

## Where to spot

- [Six Flags Great Adventure](https://www.snappit.app/guides/places/six-flags-great-adventure) — New Jersey, US · Zoo
- [Frank Buck Zoo](https://www.snappit.app/guides/places/frank-buck-zoo) — Texas, US · Zoo
- [London Aquarium](https://www.snappit.app/guides/places/london-aquarium) — England, GB · Aquarium
- [Tierpark Hamm](https://www.snappit.app/guides/places/tierpark-hamm) — Nordrhein-Westfalen, DE · Zoo
- [Emas National Park](https://www.snappit.app/guides/places/emas-national-park) — BR · Park

[View all places to see Rhea](https://www.snappit.app/guides/where-to-see/rhea)

## More Birds

- [Black-crowned Night Heron](https://www.snappit.app/explore/black-crowned-night-heron) (*Nycticorax nycticorax*)
- [Anna's Hummingbird](https://www.snappit.app/explore/annas-hummingbird) (*Calypte anna*)
- [Great Egret](https://www.snappit.app/explore/great-egret) (*Ardea alba*)
- [Blue Jay](https://www.snappit.app/explore/blue-jay) (*Cyanocitta cristata*)

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Source: [Rhea: Characteristics, Facts & Places to See — Snappit](https://www.snappit.app/explore/rhea)