What is a Rhea?

Rhea Bird Group: Rhea is the common name for any of the huge, flightless ratite birds of the genus Rhea, which are distinguished by their huge legs, long necks, and three-toed feet. The rheas, which are native to South America, are similar to African ostriches and Australian emus. The greater or American rhea (R. americana) and the lesser or Darwin's rhea (R. Darwinii) are the two species of rhea that exist (R. pennata).

As part of food chains, wild rheas provide substantial ecological benefits. Although the adult rhea has few enemies except jaguars and cougars, eggs, hatchlings, and young birds are preyed upon by a variety of predators, including the tegu lizard, maned-wolf, bush dog, armadillo, and certain birds of prey. They are omnivores who eat broad-leafed plants and seeds, roots, and fruit, as well as lizards, carrion, and small invertebrates like beetles and grasshoppers.

Humans benefit from the presence of rheas. Their meat and eggs are consumed, and their feathers and hide are used in the manufacture of feather dusters, leather, and cosmetics and soaps. They are farmed commercially, just as the ostrich and emu. Rheas provide a distinctive beauty when spotted grazing in the wild, in addition to these values.


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Rhea Bird Classification

  • Kingdom: Animalia

  • Phylum: Chordata

  • Class: Aves

  • Superorder: Paleognathae

  • Order: Rheiformes

  • Family: Rheidae

  • Genus: Rhea


Rhea Bird Physical Features

Rheas are part of the ratites, a group of birds. Ratites are flightless birds with a flat, raft-like sternum (breastbone) that lacks the keel that most flying birds and some other flightless birds have for attaching wing muscles. Other ratites include Australia's emus and Africa's ostriches, as well as New Zealand's kiwis, which are similar-looking and fast-running. The ostrich is the world's largest living bird (reaching 9 feet), and the emu is the world's second-largest extant bird (reaching 6.5 feet in height).

Rhea flightless birds are huge, grey-brown birds with long legs and necks. These birds can grow to be 5.6 feet tall (1.7 metres) and weigh up to 88 pounds (40 kilograms). Their wings are huge for a flightless bird, and when they run, they spread them out like sails. Rheas have only three toes, unlike most birds. The emu has three toes as well, while the ostrich only has two. The front of a rhea's tarsus is covered in horizontal plates. In an enlargement of the cloaca, they also store urine separately.


Rhea Bird Group Subspecies

The larger rhea has five subspecies that are difficult to discern and whose validity is debatable; their ranges intersect around the Tropic of Capricorn:

  • R. americana americana 

  • R. americana intermedia

  • R. americana nobilis 

  • R. americana araneipes 

  • R. americana albescens 

The amount of black colouring of the throat and the height are the main subspecific variations. Rheas, on the other hand, differ so little across their range that it's nearly impossible to match captive birds to subspecies without knowing where they came from.

  • R. pennata garleppi

  • R. pennata tarapacensis

  • R. pennata pennata


Rhea Behaviour and Ecology

Rheas are usually silent birds, unless when they are young or when the male is looking for a mate. During the non-breeding season, they can form flocks of up to 100 birds, however, the lesser rhea creates smaller flocks. When they are in danger, they flee in a zig-zag pattern, using one wing first, then the other, much like a rudder. During the breeding season, flocks disperse.


Rhea Bird Group Diet

They are omnivorous, preferring broad-leafed plants but also eating seeds, roots, fruit, lizards, beetles, grasshoppers, and dead animals. The larger rhea feeds mostly on broad-leaved dicot leaves and other plant materials, particularly seed and fruit when available. Native and introduced species from many dicot families, such as Amaranthaceae, Asteraceae, Bignoniaceae, Brassicaceae, Fabaceae, Lamiaceae, Myrtaceae, and Solanaceae, are among the most popular food plants. Fruit from the Magnoliidae family, such as Duguetia furfuracea (Annonaceae) or avocados (Persea americana, Lauraceae), can be seasonal. Cereal grains, as well as monocots in general, are not generally eaten by them.

However, the leaves of some grasses, such as Brachiaria brizantha, can be consumed in considerable numbers, while Liliaceae (such as the sarsaparilla Smilax brasiliensis) have been documented as food plants. Even difficult and prickly vegetable debris, such as tubers and thistles, is devoured. The greater rhea, like many other birds that consume difficult plant matter, swallows pebbles to assist ground down the material for easier digestion. It is drawn to shiny surfaces and has been known to ingest metallic or glossy objects inadvertently.

The greater rhea can be a very useful species for farmers in fields and plantations of plants they don't like to eat, such as wheat or Eucalyptus. It eats locusts and grasshoppers, true bugs, cockroaches, and other problem insects, as well as any large invertebrate it can grab. Animal matter is consumed in greater quantities by children than by adults. R. a. americana was found to be particularly fond of beetles in mixed cerrado and agricultural soil in Minas Gerais (Brazil). It's unclear whether this is true for all species, but in pampas habitat, for example, beetle intake is likely lower simply owing to availability, but Orthoptera may be more significant.

The greater rhea can consume large amounts of Hymenoptera. Many of the insects in this group can cause painful stings, yet the birds don't appear to bother. Because it readily consumes scorpions, it's possible that this species has a higher level of poison resistance. Tiny vertebrates, such as rodents, snakes, lizards, and small birds, are also consumed. Greater rheas are known to cluster near carrion to feed on flies; they are also known to eat dead or dying fish in the dry season, although not in significant quantities, as with vertebrate prey in general.


Rhea Bird Group Reproduction

Rheas are polygamous, with males being polygynous at the same time and females being serially polyandrous. In fact, this implies that during the breeding season, females roam around, mating with a man and depositing their eggs with him before leaving and mating with another male. After mating, the male constructs a nest in which each female, in turn, deposits her eggs. As a result, numerous females use the nests at the same time. After mating, the males become stationary and go to the nests with the eggs of many females, where they take care of incubation and hatchlings on their own.

After mating, the males become stationary and go to the nests with the eggs of many females, where they take care of incubation and hatchlings on their own. According to new data, dominant males may solicit the help of a subordinate male to roost for them while they construct a second nest with a new harem. The breeding season for greater rheas is between August and January, depending on the climate.


Rhea Bird Nest


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Rhea nests are made up of a simple, wide scrape in the ground that is lined with grass and leaves. The nest is kept hidden by males dragging wood, grass, and leaves in the area around the nest to create a firebreak as broad as their neck can reach.


Rhea Egg


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Ten to eighty eggs are incubated by the male. Greater rheas' nests can include up to 80 eggs laid by a dozen females, with each female's clutch containing 5-10 eggs. The greater rhea, on the other hand, has an average clutch size of 26 eggs from seven separate females. Greater rhea eggs are about half the size of an ostrich egg, measuring 130 millimetres by 90 millimetres (5.1 inches by 3.5 inches) and weighing 600 grammes (21 ounces) on average. When new, their shell is greenish-yellow, but when exposed to light, it fades to a drab cream colour.

Outside the nest, several eggs are left. These could be used as decoys, sacrificed to predators so that they don't try to break into the nest. They may decay and attract flies, which the adult and young can ingest if they are not eaten by predators. Males will charge at any perceived threat that approaches the chicks, even female rheas and people while caring for the young.

The incubation period lasts between 29 and 43 days. Even though the eggs in one nest were laid up to two weeks apart, they all hatch within 36 hours of each other. Even when still within the egg, it appears that when the first young are ready to hatch, they begin a call that sounds like a pop-bottle rocket; thus, the hatching time is synchronised. Greater rheas are half-grown in three months, full adult size in six months, and sexually mature in their fourteenth month, although they do not reproduce until they are two years old.


Rhea Bird Predators

The cougar (Puma concolor) and the jaguar are the only natural predators of adult larger rheas (Panthera onca). Younger birds have been known to be killed by feral dogs, and the Southern caracara (Caracara plancus) is thought to prey on hatchlings. Nests that had been undermined by a six-banded armadillo (Euphractus sexcinctus) or a huge hairy armadillo (Chaetophractus villosus) and the rhea eggs had been split apart have been discovered. Bush dogs (Speothos venaticus), maned wolves (Chrysocyon brachyurus), tegu lizards (Tupinambis teguixin), and several birds of prey are among the other primary predators.

Greater rheas bred in captivity show significant ecological naivete. If the birds are reintroduced into the wild as part of reintroduction operations, their fearlessness makes them extremely vulnerable to predators. Traditional predator conditioning of greater rhea juveniles can help to prevent this to some extent, but the personality type of the birds—whether they are brave or shy—influences the success of such training. A methodology for training larger rheas to avoid would-be predators and identifying the most cautious animals for release was devised in 2006.

Greater or American Rhea Bird


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The grey, common, or American rhea (Rhea americana) is another name for the greater rhea (Rhea americana). The eastern section of South America is home to this flightless bird, which is not only the largest species of the genus Rhea but also the largest American bird alive. It's also famous for its reproductive behaviours, as well as the fact that a group has recently established itself in Germany. It is called as and (Spanish) or ema (English) in its native range (Portuguese).

Adults weigh 20–27 kg (44–60 lb) on average and measure 129 cm (51 in) from beak to tail, standing around 1.50 m (5 ft) tall. Males are considerably larger than females, weighing up to 40 kilogrammes (88 lb) and measuring more than 150 centimetres (59 in) in length.

The American rhea's wings are quite long, and the birds use them to keep their balance when sprinting through tight curves. The plumage of the greater rheas is fluffy and torn. The feathers are grey or brown in colour, with a lot of variance between individuals. Males are generally darker than females. Albinos and leucistic individuals (with white body plumage and blue eyes) can be found in the wild, particularly in Argentina. Greater rheas hatchlings are grey with black lengthwise stripes.

Argentina, Bolivia, Brazil, Paraguay, and Uruguay are home to the greater rhea. This species favours places with at least some tall vegetation, such as those dominated by satintail (Imperata) and bahiagrass (Paspalum) species, as well as savanna, scrub woodland, chaparral, and even desert and palustrine habitats. It is not found in the wet tropical forests of the Mata Atlântica or the planalto uplands along Brazil's coast, although it does extend south to 40 degrees latitude. It dwells near water during the breeding season (spring and summer).


Lesser or Darwin’s Rhea Bird


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The smaller of the two extant species of rheas, Darwin's rhea (Rhea pennata), is also known as the lesser rhea. It can be found in South America's Altiplano and Patagonia.

It is 90–100 cm (35–39 in) tall, weighs 15–25 kg (33–55 lb), and has longer wings than other ratites, allowing it to run faster. It has a top speed of 60 kilometres per hour (37 miles per hour), allowing it to outrun predators. The toes' sharp claws are efficient weapons. The upper portion of their tarsus is feathered, and their plumage is speckled brown and white.

Darwin's rhea can be found in open scrub in Patagonia's grasslands and on the Andean plateau (the Altiplano), which runs through Argentina, Bolivia, Chile, and Peru. Grasslands, brushlands, and marshes are preferred habitats for all subspecies. The nominate subspecies, on the other hand, prefer heights of less than 1,500 metres (4,900 feet), whereas the other subspecies prefer elevations of 3,000–4,500 metres (9,800–15,000 feet), but can be found as low as 1,500 metres (4,900 feet) in the south.

When this species' males are incubating eggs, they become hostile. As a result, the latter eggs are laid near the nest rather than in it by the females. The male moves most of the eggs into the nest, while some remain outside. As previously stated, if these eggs are not eaten by predators, they will decay and attract flies, which the male and eventually the chicks will consume. The clutch size ranges from 5 to 55 eggs, and the incubation period is 30–44 days. The eggs are greenish-yellow and measure 87–126 mm (3.4–5.0 in).

Outside of the breeding season, Darwin's rhea is a friendly bird, living in groups of 5 to 30 birds of various ages and sexes.


Rhea Bird Group Conservation

The greatest threats to Darwin's rhea include hunting, egg collection, and habitat fragmentation due to conversion to agriculture or pastures for cattle grazing. The whole range is estimated to be 1,100,000 square kilometres (420,000 sq mi). The southern nominate subspecies is still reasonably abundant and widespread, but the situation for the two northern subspecies is more concerning, with a total population estimated to be in the hundreds.

According to the IUCN, the larger rhea is also designated as a Near Threatened species. Although the species is thought to be diminishing, it is still rather common across its vast range of 6,540,000 km2

FAQs (Frequently Asked Questions)

1. What are the Uses of Rhea Birds?

Ans. Rheas have a wide range of applications in South America. Feathers are used to make feather dusters, skins are used to make cloaks or leather, and their meat is a common food source for many people. The greater rhea, like the emu and ostrich, is farmed throughout North America and Europe. Meat and eggs are the principal goods, although rhea oil is used in cosmetics and soaps, and rhea leather is also widely trafficked. During the breeding season, male greater rheas are extremely territorial. In ordinary confinement farming scenarios, infant chicks have a high death rate, but under ideal free-range settings, chicks will reach adult size by the fifth month.

2. Which One is Bigger: Rhea or Ostrich?

Ans. Rhea is one of two giant, flightless birds in the Rheidae family of the Rheiformes order. They are related to the ostrich and the emu and are endemic to South America. The common rhea stands around 120 cm (4 feet) tall and weighs around 20 kg, which is significantly less than the ostrich (50 pounds).