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Greater Rhea

Rhea americana

  1. Not Evaluated
  2. Data Deficient
  3. Least Concern
  4. Near Threatened
  5. Vulnerable
  6. Endangered
  7. Critically Endangered
  8. Extinct in the Wild
  9. Extinct

About Us

The greater rhea is the largest bird on the American continent. It is part of the ‘ratite’ family, a group of birds which ostrich, emu, kiwi and cassowary are also a part of. They are a flightless bird, with strong powerful legs, allowing them to run up to 35mph.

Here at Woburn we have four adult Rhea, our male ‘He man’, and our three females ‘superwoman’, ‘she-ra’, and ‘wonder woman’. You will find them out grazing the grass, sunning themselves, or during breeding season you will find the male sitting on his nest full of eggs, or with his chicks following him around!

Distribution
Brazil, Bolivia, Paraguay, Uruguay and Argentina
Habitat
Tall grassland, open woodland, wooded savannah and occasionally crop fields
Height
129 - 1 50cm tall
Weight
20 - 40kg
Lifespan
In the wild 10 -15 years, in captivity up to 30 years
Threats
Hunting for eggs, meat, feathers and skins

Physical Features

The rhea is the largest bird in the Americas. They are unmistakable due to their large size, long legs, and lack of ability to fly.  They are superficially very similar to the ostrich, which led Charles Darwin to first describe them as a ‘South American ostrich’, although they are not thought to be directly related.

The body is greyish in colour, with dark bands around the neck and upper back. There are whitish feathers on the wings, under body, and thighs. The dark ring around the bottom of the neck will darken during the breeding season in males.

The rhea lacks the keel bone which is found in most birds, this is the bone which the flight muscles are usually attached to, but as these are flightless birds they lack it completely. The wings of the rhea are large for a terrestrial bird, however they will use them to help balance and steer them when running. The feathers are not needed for flight so they are long and plume-like.

The legs of the rhea are long and powerful, similar to those of an ostrich, allowing them to run at high speeds and for long distances. They feature three large toes on each foot.

Although they do not fly they are well adapted to running, at speeds of up to 35mph, and are also very good swimmers.

An adult will weigh between 20 to 40kg, and be up to 150cm tall. The juvenile bird will be fully grown by the age of six months.

Diet

Rhea feed mainly on plant matter, such as roots, leaves, fruits, and seeds. They will also eat insects, lizards, frogs, small birds, and even snakes. 

Like some other birds, rhea will swallow pebbles to help digest their food.

They are well known for eating agricultural crops and so are seen as a pest by many farmers, although evidence suggests they benefit crops by eating weeds.

The rhea will often feed with other animals, taking advantage of them to find food and for protection. They can be seen feeding alongside herds of pampas deer, guanacos, and domestic livestock.

Social Structure and Communication

For the greater part of the year rhea will live in mixed flocks of up to 30 or more birds. During the breeding season males become solitary and territorial, with females separating into small groups of up to 12 individuals. Males will establish a territory and will then fight to attract the small groups of females to their territory.

They are a very social animal, often forming mixed herds to forage with pampas deer, guanacos, and domestic animals. This allows them to find food sources more readily, and gives an element of protection and safety in numbers.

Rhea are generally silent, except for the male, performing a low ‘grunt’ as part of his courtship display, and the young chicks, who will call to their parents when young.  Adults, especially breeding males, may ‘hiss’ when protecting the nest of young or when feeling threatened. They instead communicate mainly through body language, using their wings for threat displays and courtship displays.

Breeding

During the breeding season males become solitary and territorial, with females separating into small groups of up to 12 individuals. Males will establish a territory and will then fight to attract the small groups of females.  This territorial competition usually consists of threats, or fights, biting, kicking, and locking necks with rival males. During courtship males will emit a low ‘grunt’ noise to attract females.

The male will build a nest, only a shallow scrape in the ground. He will then attract females to this nest, who will all lay eggs. The female can lay 8 to 10 eggs, one a day. Each female will lay her eggs in the nest, meaning the male can have up to 80 eggs to incubate. Once all the eggs are laid he will start to incubate them, this will take around 35 to 40 days, and once one egg has started it will set off a synchronised hatching, with all eggs hatching in a 35 hour period of each other.

The male will rear the young, taking care of them for up to four months. They will shelter under his wings when threatened, or when too hot or cold. The females play no part in the rearing of the young. The juveniles will stay together, even after they leave their parent, until they reach sexual maturity at the age of around two years.

Husbandry and Enrichment

Rhea will spend most of their time in the wild moving as a group, grazing. Here at Woburn we feed our rhea a specialised diet, but we also give them the freedom to naturally graze on grass and vegetation in their large enclosure.

 Just as in the wild they will feed alongside other species, in the wild this will be animals such as pampas deer, guanacos, and domestic livestock. Here at Woburn they live with our large group of wallaby, who they happily form a mixed herd with when foraging, feeding, and even sleeping.

Our rhea will dig their own shallow scrapes into the ground to sleep and sunbathe in, just as in the wild. They will also nest, and breed naturally.

Threats and Conservation

Populations of rhea are decreasing greatly in South America. Although the adults have no predators the young may be taken by dogs and other terrestrial predators. The adults suffer from hunting for various uses. The eggs and meat are taken for food, and often as food for domestic dogs. The feathers are used to make feather dusters, and the skin is used for leather.

They are often seen as pests by farmer due to their supposed habit of eating agricultural crops, and are often killed for this reason; however there is strong evidence that the rhea play a positive role in agriculture, eating the weeds and pest species of plant, not the crops.

Habitat loss effects rhea, with large areas of grassland being converted to crops and roads, and developed areas causing habitat destruction, and barriers between territories and feeding grounds.

There is a large population of around 100 greater rhea living in rural Germany, after several breeding pairs escaped from a farm. This group live in a large agricultural area and are thriving, with numbers climbing each year.

Commercial farming of rhea for meat, eggs, skin and feathers has become popular in recent times. This can help give greater insight and research into rhea breeding, and can help with captive breeding for reintroduction.

They are listed as appendix II of CITES, which means the trade and export of this species is heavily regulated and controlled to protect them.

Fun Facts

A small group of escaped birds survived and bred to form a wild group of over 100 birds in Germany!

Rhea will swallow pebbles to help them digest their food!

Rhea are generally silent birds, only making noises during the breeding season or when threatened!