American Rhea
Encyclopedia
The Greater Rhea, Rhea americana, is a flightless bird
found in eastern South America
. Other names for the Greater Rhea include the Grey, Common, American Rhea, ñandú (Guarani
) or ema (Portuguese). One of two species in the genus Rhea
, in the family Rheidae, the Greater Rhea is endemic to Argentina
, Bolivia
, Brazil
, Paraguay
, and Uruguay
. It inhabits a variety of open areas, such as grassland
s, savanna
or grassy wetlands. It has a length of 3–5 ft (0.9144–1.5 m) and a wingspan of 5 feet (1.5 m). Weighing 50–55 lb (22.7–24.9 kg), the Greater Rhea is the largest bird in South America. In the wild, the Greater Rhea has a life expectancy of 15 years. It is also notable for its reproductive habits, and for the fact that a group has established itself in Germany
in recent years.
, a Greek goddess, and the Latinized form of America. It was originally described by Carolus Linnaeus
in his 18th-century work, Systema Naturae
under its current binomial name. He identified specimens from Sergipe
, and Rio Grande do Norte
, Brazil
, in 1758. They are from the family Rheidae, and the order Struthioniformes, commonly known as ratite
s. They are joined in this order by Emu
s, Ostrich
es, cassowaries
, and kiwi
s, along with the extinct forms moa
s, and elephant bird
s.
of the Greater Rhea; their ranges meet around the Tropic of Capricorn
:
Main subspecific differences are the extent of the black coloring of the throat and the height. However, subspecies of the Greater Rhea differ so little across their range that, without knowledge of the place of origin, it is essentially impossible to identify captive birds by subspecies.
The adults have an average weight of 20–27 kg (44.1–59.5 lb) and measure 129 cm (50.8 in) long from beak to tail; they usually stand about 1.5 m (4.9 ft) tall. The males are generally bigger than the females. Large males can weigh up to 40 kilograms (88.2 lb), stand nearly 1.83 m (6 ft) tall and measure over 150 cm (59.1 in) long.
The legs are long and strong, and have three toes. The wings of the American rhea are rather long; the birds use them during running to maintain balance during tight turns.
Greater Rheas have a fluffy, tattered-looking plumage. The feathers are gray or brown, with high individual variation, In general, males are darker than females. Even in the wild—particularly in Argentina—leucistic
individuals (with white body plumage and blue eyes) as well as albinos occur. Hatchling Greater Rheas are grey with dark lengthwise stripes.
, Bolivia
, Brazil
, Paraguay
, and Uruguay
. This species inhabits grassland dominated by satintail (Imperata) and bahiagrass (Paspalum) species, as well as savanna
, scrub forest, chaparral
, and even desert
and palustrine
lands, though it prefers areas with at least some tall vegetation. It is absent from the humid tropical forests of the Mata Atlântica
and planalto
uplands along the coast of Brazil and extends south to 40° latitude
. During the breeding season (spring and summer), it stays near water.
A small population of the Greater Rhea has become established in Germany
. Three pairs escaped from a farm in Gross Grönau, Schleswig-Holstein
, in August 2000. These birds survived the winter and succeeded in breeding in a habitat sufficiently similar to their native South American range. They eventually crossed the Wakenitz
river and settled in Mecklenburg-Vorpommern in the area around and particularly to the north of Thandorf
village. As of late 2000 the population was estimated to be seven birds and in 2001 eighteen birds. In October 2008 the population was estimated by two German scientists at around 100 birds (Korthals, A. & F. Philipp).
These rheas are legally protected in Germany in a similar way to native species. In its new home, the Greater Rhea is considered generally beneficial as its browsing helps maintain the habitat
diversity of the sparsely populated grasslands bordering the Schaalsee
biosphere reserve
.
The bulk of its food consists of broad-leaved dicot foliage and other plantstuffs, particularly seed
and fruit
when in season. Favorite food plants include native and introduced species
from all sorts of dicot families
, such as Amaranthaceae
, Asteraceae
, Bignoniaceae
, Brassicaceae
, Fabaceae
, Lamiaceae
, Myrtaceae
or Solanaceae
. Magnoliidae
fruit, for example of Duguetia furfuracea (Annonaceae
) or avocados (Persea americana, Lauraceae
) can be seasonally important. They do not usually eat cereal
grains, or monocots in general. However, the leaves of particular grass
species like Brachiaria brizantha can be eaten in large quantities, and Liliaceae
(e.g. the sarsaparilla
Smilax brasiliensis) have also been recorded as foodplants. Even tough and spiny vegetable matter like tuber
s or thistle
s is eaten with relish. Like many birds which feed on tough plant matter, the Greater Rhea swallows pebble
s which help grind down the food for easy digestion. It is much attracted to sparkling objects and sometimes accidentally swallows metallic or glossy objects.
In field
s and plantation
s of plants they do not like to eat, e.g., cereal
s or eucalyptus
, the Greater Rhea can be a species quite beneficial to farmers. It will eat any large invertebrate
it can catch; its food includes locust
s and grasshopper
s, true bugs, cockroach
es, and other pest insect
s. Juveniles eat more animal matter than adults. In mixed cerrado
and agricultural land in Minas Gerais
(Brazil), R. a. americana was noted to be particularly fond of beetle
s. It is not clear whether this applies to the species in general but for example in pampas habitat, beetle consumption is probably lower simply due to availability while Orthoptera
might be more important. The Greater Rhea is able to eat Hymenoptera
in quantity. These insect
s contain among them many who can give painful stings, though the birds do not seem to mind. It may be that this species has elevated resistance to poison, as it readily eats scorpion
s. But even small vertebrate
s like rodent
s, snake
s, lizard
s, and small bird
s are eaten. Sometimes, Greater Rheas will gather at carrion
to feed on flies
; they are also known to eat dead or dying fish
in the dry season, but as vertebrate prey in general not in large quantities.
The natural predators of adult Greater Rheas are limited to the Cougar (Puma concolor) and the Jaguar
(Panthera onca). Feral dog
s are known to kill younger birds, and the Southern Caracara
(Caracara plancus) is suspected to prey on hatchlings. Armadillo
s sometimes feed on Greater Rhea eggs; nests have been found which had been undermined by a Six-banded Armadillo
(Euphractus sexcinctus) or a Big Hairy Armadillo
(Chaetophractus villosus) and the rhea eggs were broken apart.
Captive-bred Greater Rheas exhibit significant ecological naïvete. This fearlessness renders them highly vulnerable to predators if the birds are released into the wild in reintroduction
projects. Classical conditioning
of Greater Rhea juveniles against predator models can prevent this to some degree, but the personality type
of the birds—whether they are bold or shy—influences the success of such training. In 2006, a protocol was established for training Greater Rheas to avoid would-be predators, and for identifying the most cautious animals for release.
Greater Rheas breed in the warmer months, between August and January depending on the climate. Males are simultaneously polygynous, females are serially polyandrous. In practice, this means that the females move around during breeding season, mating with a male and depositing their eggs with the male before leaving him and mating with another male. Males on the other hand are sedentary, attending the nests and taking care of incubation and the hatchlings all on their own. Although recent evidence suggest that dominant males may enlist a subordinate male to roost for him while he starts a second nest with a second harem. The nests are thus collectively used by several females and can contain as many as 80 eggs
laid by a dozen females; each individual female's clutch
numbers some 5–10 eggs. However, the average clutch size is 26 with 7 different females eggs.
Rhea eggs measure about 130 by 90 mm (5.1 by 3.5 in) and weigh 600 g (21.2 oz) on average; they are thus less than half the size of an ostrich
egg. Their shell is greenish-yellow when fresh but soon fades to dull cream when exposed to light. The nest is a simple shallow and wide scrape in a hidden location; males will drag sticks, grass, and leaves in the area surrounding the nest so it resembles a firebreak as wide as their neck can reach.
The incubation period is 29–43 days. All the eggs hatch within 36 hours of each other even though the eggs in one nest were laid perhaps as much as two weeks apart. As it seems, when the first young are ready to hatch they start a call resembling a pop-bottle rocket, even while still inside the egg, thus the hatching time is coordinated. Greater Rheas are half-grown about three months after hatching, and sexually mature by their 14th month.
species according to the IUCN. The species is believed to be declining due to increased hunting and the conversion of central South American grasslands to farmland. The populations of Argentina and Uruguay are most seriously affected by the decline.
Farmers sometimes consider the Greater Rhea pests, because they will eat broad-leaved crop plants, such as cabbage
, chard
and bok choi. Where they occur as pests, farmers tend to hunt and kill Greater Rheas. The burning of crops in South America
has also contributed to their decline.
International trade in wild-caught Greater Rheas is restricted as per CITES Appendix II.
and Europe
similar to the Emu
and Ostrich
. The main products are meat
and eggs
, but rhea oil is used for cosmetics and soaps and rhea leather
is also traded in quantity. Male Greater Rheas are very territorial during the breeding season. The infant chicks have high mortality in typical confinement farming situations, but under optimum free-range conditions chicks will reach adult size by their fifth month.
Flightless bird
Flightless birds are birds which lack the ability to fly, relying instead on their ability to run or swim. They are thought to have evolved from flying ancestors. There are about forty species in existence today, the best known being the ostrich, emu, cassowary, rhea, kiwi, and penguin...
found in eastern South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. Other names for the Greater Rhea include the Grey, Common, American Rhea, ñandú (Guarani
Guaraní language
Guaraní, specifically the primary variety known as Paraguayan Guaraní , is an indigenous language of South America that belongs to the Tupí–Guaraní subfamily of the Tupian languages. It is one of the official languages of Paraguay , where it is spoken by the majority of the population, and half of...
) or ema (Portuguese). One of two species in the genus Rhea
Rhea (bird)
The rheas are ratites in the genus Rhea, native to South America. There are two existing species: the Greater or American Rhea and the Lesser or Darwin's Rhea. The genus name was given in 1752 by Paul Möhring and adopted as the English common name. Möhring's reason for choosing this name, from the...
, in the family Rheidae, the Greater Rhea is endemic to Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
, Bolivia
Bolivia
Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
, Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, Paraguay
Paraguay
Paraguay , officially the Republic of Paraguay , is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Paraguay lies on both banks of the Paraguay River, which runs through the center of the...
, and Uruguay
Uruguay
Uruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...
. It inhabits a variety of open areas, such as grassland
Grassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...
s, savanna
Savanna
A savanna, or savannah, is a grassland ecosystem characterized by the trees being sufficiently small or widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses.Some...
or grassy wetlands. It has a length of 3–5 ft (0.9144–1.5 m) and a wingspan of 5 feet (1.5 m). Weighing 50–55 lb (22.7–24.9 kg), the Greater Rhea is the largest bird in South America. In the wild, the Greater Rhea has a life expectancy of 15 years. It is also notable for its reproductive habits, and for the fact that a group has established itself in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
in recent years.
Taxonomy
The Greater Rhea derives its scientific name from RheaRhea (mythology)
Rhea was the Titaness daughter of Uranus, the sky, and Gaia, the earth, in Greek mythology. She was known as "the mother of gods". In earlier traditions, she was strongly associated with Gaia and Cybele, the Great Goddess, and was later seen by the classical Greeks as the mother of the Olympian...
, a Greek goddess, and the Latinized form of America. It was originally described by Carolus Linnaeus
Carolus Linnaeus
Carl Linnaeus , also known after his ennoblement as , was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology...
in his 18th-century work, Systema Naturae
Systema Naturae
The book was one of the major works of the Swedish botanist, zoologist and physician Carolus Linnaeus. The first edition was published in 1735...
under its current binomial name. He identified specimens from Sergipe
Sergipe
Sergipe , is the smallest state of the Brazilian Federation, located on the northeastern Atlantic coast of the country. It borders on two other states, Bahia to the south and west and Alagoas to the north, and to the east is the Atlantic Ocean...
, and Rio Grande do Norte
Rio Grande do Norte
Rio Grande do Norte is one of the states of Brazil, located in the northeastern region of the country, occupying the northeasternmost tip of the South American continent. Because of its geographic position, Rio Grande do Norte has a strategic importance. The capital and largest city is Natal...
, Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, in 1758. They are from the family Rheidae, and the order Struthioniformes, commonly known as ratite
Ratite
A ratite is any of a diverse group of large, flightless birds of Gondwanan origin, most of them now extinct. Unlike other flightless birds, the ratites have no keel on their sternum—hence the name from the Latin ratis...
s. They are joined in this order by Emu
Emu
The Emu Dromaius novaehollandiae) is the largest bird native to Australia and the only extant member of the genus Dromaius. It is the second-largest extant bird in the world by height, after its ratite relative, the ostrich. There are three subspecies of Emus in Australia...
s, Ostrich
Ostrich
The Ostrich is one or two species of large flightless birds native to Africa, the only living member of the genus Struthio. Some analyses indicate that the Somali Ostrich may be better considered a full species apart from the Common Ostrich, but most taxonomists consider it to be a...
es, cassowaries
Cassowary
The cassowaries are ratites, very large flightless birds in the genus Casuarius native to the tropical forests of New Guinea, nearby islands and northeastern Australia. There are three extant species recognized today...
, and kiwi
Kiwi
Kiwi are flightless birds endemic to New Zealand, in the genus Apteryx and family Apterygidae.At around the size of a domestic chicken, kiwi are by far the smallest living ratites and lay the largest egg in relation to their body size of any species of bird in the world...
s, along with the extinct forms moa
Moa
The moa were eleven species of flightless birds endemic to New Zealand. The two largest species, Dinornis robustus and Dinornis novaezelandiae, reached about in height with neck outstretched, and weighed about ....
s, and elephant bird
Elephant bird
Elephant birds are an extinct family of flightless birds found only on the island of Madagascar and comprising the genera Aepyornis and Mullerornis.-Description:...
s.
Subspecies
There are five subspeciesSubspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
of the Greater Rhea; their ranges meet around the Tropic of Capricorn
Tropic of Capricorn
The Tropic of Capricorn, or Southern tropic, marks the most southerly latitude on the Earth at which the Sun can be directly overhead. This event occurs at the December solstice, when the southern hemisphere is tilted towards the Sun to its maximum extent.Tropic of Capricorn is one of the five...
:
- R. a. americana – campos of northern and eastern BrazilBrazilBrazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
- R. a. intermedia – UruguayUruguayUruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...
and extreme southeastern BrazilBrazilBrazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
(Rio Grande do SulRio Grande do SulRio Grande do Sul is the southernmost state in Brazil, and the state with the fifth highest Human Development Index in the country. In this state is located the southernmost city in the country, Chuí, on the border with Uruguay. In the region of Bento Gonçalves and Caxias do Sul, the largest wine...
province) - R. a. nobilis – eastern ParaguayParaguayParaguay , officially the Republic of Paraguay , is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Paraguay lies on both banks of the Paraguay River, which runs through the center of the...
, east of Rio Paraguay - R. a. araneipes – chaco of ParaguayParaguayParaguay , officially the Republic of Paraguay , is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Paraguay lies on both banks of the Paraguay River, which runs through the center of the...
and BoliviaBoliviaBolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
and the Mato GrossoMato GrossoMato Grosso is one of the states of Brazil, the third largest in area, located in the western part of the country.Neighboring states are Rondônia, Amazonas, Pará, Tocantins, Goiás and Mato Grosso do Sul. It also borders Bolivia to the southwest...
province of BrazilBrazilBrazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people... - R. a. albescens – plains of ArgentinaArgentinaArgentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
south to the Rio NegroRío Negro ProvinceRío Negro is a province of Argentina, located at the northern edge of Patagonia. Neighboring provinces are from the south clockwise Chubut, Neuquén, Mendoza, La Pampa and Buenos Aires. To the east lies the Atlantic Ocean.Its capital is Viedma...
province
Main subspecific differences are the extent of the black coloring of the throat and the height. However, subspecies of the Greater Rhea differ so little across their range that, without knowledge of the place of origin, it is essentially impossible to identify captive birds by subspecies.
Description
The legs are long and strong, and have three toes. The wings of the American rhea are rather long; the birds use them during running to maintain balance during tight turns.
Greater Rheas have a fluffy, tattered-looking plumage. The feathers are gray or brown, with high individual variation, In general, males are darker than females. Even in the wild—particularly in Argentina—leucistic
Leucistic
Leucism is a condition characterized by reduced pigmentation in animals and humans. Unlike albinism, it is caused by a reduction in all types of skin pigment, not just melanin.- Details :...
individuals (with white body plumage and blue eyes) as well as albinos occur. Hatchling Greater Rheas are grey with dark lengthwise stripes.
Distribution, ecology and status
The Greater Rhea is endemic to ArgentinaArgentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
, Bolivia
Bolivia
Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
, Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, Paraguay
Paraguay
Paraguay , officially the Republic of Paraguay , is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Paraguay lies on both banks of the Paraguay River, which runs through the center of the...
, and Uruguay
Uruguay
Uruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...
. This species inhabits grassland dominated by satintail (Imperata) and bahiagrass (Paspalum) species, as well as savanna
Savanna
A savanna, or savannah, is a grassland ecosystem characterized by the trees being sufficiently small or widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses.Some...
, scrub forest, chaparral
Chaparral
Chaparral is a shrubland or heathland plant community found primarily in the U.S. state of California and in the northern portion of the Baja California peninsula, Mexico...
, and even desert
Desert
A desert is a landscape or region that receives an extremely low amount of precipitation, less than enough to support growth of most plants. Most deserts have an average annual precipitation of less than...
and palustrine
Palustrine
Palustrine comes from the Latin word palus or marsh. Wetlands within this category include inland marshes and swamps as well as bogs, fens, tundra and floodplains...
lands, though it prefers areas with at least some tall vegetation. It is absent from the humid tropical forests of the Mata Atlântica
Mata Atlântica
The Atlantic Forest is a region of tropical and subtropical moist forest, tropical dry forest, tropical savanna, semi deciduous forest and mangrove forests which extends along the Atlantic coast of Brazil from Rio Grande do Norte state in the north to Rio Grande do Sul state in the south, and...
and planalto
Planalto
-Buildings:* Palácio do Planalto, Brasília, the official seat of the President of Brazil.** The staff and offices of the Executive branch of the Brazilian Government, by metonymy-Places:*Planalto, Bahia *Planalto, Paraná *Planalto, Rio Grande do Sul...
uplands along the coast of Brazil and extends south to 40° latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
. During the breeding season (spring and summer), it stays near water.
A small population of the Greater Rhea has become established in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
. Three pairs escaped from a farm in Gross Grönau, Schleswig-Holstein
Schleswig-Holstein
Schleswig-Holstein is the northernmost of the sixteen states of Germany, comprising most of the historical duchy of Holstein and the southern part of the former Duchy of Schleswig...
, in August 2000. These birds survived the winter and succeeded in breeding in a habitat sufficiently similar to their native South American range. They eventually crossed the Wakenitz
Wakenitz
The Wakenitz is a river in southeastern Schleswig-Holstein whose source is the Ratzeburger See in Ratzeburg.The Wakenitz is about 14.5 kilometers long and drains into the Trave in Lübeck. The majority of its eastern bank forms the border between Schleswig-Holstein and Mecklenburg-Western Pomerania...
river and settled in Mecklenburg-Vorpommern in the area around and particularly to the north of Thandorf
Thandorf
Thandorf is a municipality in the Nordwestmecklenburg district, in Mecklenburg-Vorpommern, Germany....
village. As of late 2000 the population was estimated to be seven birds and in 2001 eighteen birds. In October 2008 the population was estimated by two German scientists at around 100 birds (Korthals, A. & F. Philipp).
These rheas are legally protected in Germany in a similar way to native species. In its new home, the Greater Rhea is considered generally beneficial as its browsing helps maintain the habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
diversity of the sparsely populated grasslands bordering the Schaalsee
Schaalsee
Schaalsee is a lake in Germany. It forms part of the border between Schleswig-Holstein and Mecklenburg-Vorpommern . The town of Zarrentin is located on its southern shores...
biosphere reserve
Biosphere reserve
The Man and the Biosphere Programme of UNESCO was established in 1971 to promote interdisciplinary approaches to management, research and education in ecosystem conservation and sustainable use of natural resources.-Development:...
.
Food and predators
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
and fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
when in season. Favorite food plants include native and introduced species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
from all sorts of dicot families
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
, such as Amaranthaceae
Amaranthaceae
The flowering plant family Amaranthaceae, the Amaranth family, contains about 176 genera and 2,400 species.- Description :Most of these species are herbs or subshrubs; very few are trees or climbers. Some species are succulent....
, Asteraceae
Asteraceae
The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...
, Bignoniaceae
Bignoniaceae
The Bignoniaceae, or Trumpet Creeper Family, is a family of flowering plants comprising about 650-750 species in 116-120 genera. Members of the family are mostly trees and lianas , shrubs and more rarely herbaceous plants. As climber plants, they are twine climbers or tendril climbers, and rarely...
, Brassicaceae
Brassicaceae
Brassicaceae, a medium sized and economically important family of flowering plants , are informally known as the mustards, mustard flowers, the crucifers or the cabbage family....
, Fabaceae
Fabaceae
The Fabaceae or Leguminosae, commonly known as the legume, pea, or bean family, is a large and economically important family of flowering plants. The group is the third largest land plant family, behind only the Orchidaceae and Asteraceae, with 730 genera and over 19,400 species...
, Lamiaceae
Lamiaceae
The mints, taxonomically known as Lamiaceae or Labiatae, are a family of flowering plants. They have traditionally been considered closely related to Verbenaceae, but in the 1990s, phylogenetic studies suggested that many genera classified in Verbenaceae belong instead in Lamiaceae...
, Myrtaceae
Myrtaceae
The Myrtaceae or Myrtle family are a family of dicotyledon plants, placed within the order Myrtales. Myrtle, clove, guava, feijoa, allspice, and eucalyptus belong here. All species are woody, with essential oils, and flower parts in multiples of four or five...
or Solanaceae
Solanaceae
Solanaceae are a family of flowering plants that include a number of important agricultural crops as well as many toxic plants. The name of the family comes from the Latin Solanum "the nightshade plant", but the further etymology of that word is unclear...
. Magnoliidae
Magnoliidae
Magnoliids are a group of about 9,000 species of flowering plants, including magnolias, nutmeg, bay laurel, cinnamon, avocado, black pepper, and many others. They are characterized by trimerous flowers, pollen with one pore, and usually branching-veined leaves.-Classification:Traditionally,...
fruit, for example of Duguetia furfuracea (Annonaceae
Annonaceae
Annonaceae, also called the custard apple familyis a family of flowering plants consisting of trees, shrubs or rarely lianas.With about 2300 to 2500 species and more than 130 genera,...
) or avocados (Persea americana, Lauraceae
Lauraceae
The Lauraceae or Laurel family comprises a group of flowering plants included in the order Laurales. The family contains about 55 genera and over 3500, perhaps as many as 4000, species world-wide, mostly from warm or tropical regions, especially Southeast Asia and South America...
) can be seasonally important. They do not usually eat cereal
Cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...
grains, or monocots in general. However, the leaves of particular grass
Grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...
species like Brachiaria brizantha can be eaten in large quantities, and Liliaceae
Liliaceae
The Liliaceae, or the lily family, is a family of monocotyledons in the order Liliales. Plants in this family have linear leaves, mostly with parallel veins but with several having net venation , and flower arranged in threes. Several have bulbs, while others have rhizomes...
(e.g. the sarsaparilla
Sarsaparilla
is a perennial trailing vine with prickly stems that is native to Central America. Common names include Sarsaparilla , Honduran Sarsaparilla, and Jamaican Sarsaparilla...
Smilax brasiliensis) have also been recorded as foodplants. Even tough and spiny vegetable matter like tuber
Tuber
Tubers are various types of modified plant structures that are enlarged to store nutrients. They are used by plants to survive the winter or dry months and provide energy and nutrients for regrowth during the next growing season and they are a means of asexual reproduction...
s or thistle
Thistle
Thistle is the common name of a group of flowering plants characterised by leaves with sharp prickles on the margins, mostly in the family Asteraceae. Prickles often occur all over the plant – on surfaces such as those of the stem and flat parts of leaves. These are an adaptation that protects the...
s is eaten with relish. Like many birds which feed on tough plant matter, the Greater Rhea swallows pebble
Pebble
A pebble is a clast of rock with a particle size of 4 to 64 millimetres based on the Krumbein phi scale of sedimentology. Pebbles are generally considered to be larger than granules and smaller than cobbles . A rock made predominantly of pebbles is termed a conglomerate...
s which help grind down the food for easy digestion. It is much attracted to sparkling objects and sometimes accidentally swallows metallic or glossy objects.
Field (agriculture)
In agriculture, the word field refers generally to an area of land enclosed or otherwise and used for agricultural purposes such as:* Cultivating crops* Usage as a paddock or, generally, an enclosure of livestock...
s and plantation
Plantation
A plantation is a long artificially established forest, farm or estate, where crops are grown for sale, often in distant markets rather than for local on-site consumption...
s of plants they do not like to eat, e.g., cereal
Cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...
s or eucalyptus
Eucalyptus
Eucalyptus is a diverse genus of flowering trees in the myrtle family, Myrtaceae. Members of the genus dominate the tree flora of Australia...
, the Greater Rhea can be a species quite beneficial to farmers. It will eat any large invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
it can catch; its food includes locust
Locust
Locusts are the swarming phase of short-horned grasshoppers of the family Acrididae. These are species that can breed rapidly under suitable conditions and subsequently become gregarious and migratory...
s and grasshopper
Grasshopper
The grasshopper is an insect of the suborder Caelifera in the order Orthoptera. To distinguish it from bush crickets or katydids, it is sometimes referred to as the short-horned grasshopper...
s, true bugs, cockroach
Cockroach
Cockroaches are insects of the order Blattaria or Blattodea, of which about 30 species out of 4,500 total are associated with human habitations...
es, and other pest insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s. Juveniles eat more animal matter than adults. In mixed cerrado
Cerrado
The Cerrado, is a vast tropical savanna ecoregion of Brazil, particularly in the states of Gioas and Minas Gerais...
and agricultural land in Minas Gerais
Minas Gerais
Minas Gerais is one of the 26 states of Brazil, of which it is the second most populous, the third richest, and the fourth largest in area. Minas Gerais is the Brazilian state with the largest number of Presidents of Brazil, the current one, Dilma Rousseff, being one of them. The capital is the...
(Brazil), R. a. americana was noted to be particularly fond of beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s. It is not clear whether this applies to the species in general but for example in pampas habitat, beetle consumption is probably lower simply due to availability while Orthoptera
Orthoptera
Orthoptera is an order of insects with paurometabolous or incomplete metamorphosis, including the grasshoppers, crickets and locusts.Many insects in this order produce sound by rubbing their wings against each other or their legs, the wings or legs containing rows of corrugated bumps...
might be more important. The Greater Rhea is able to eat Hymenoptera
Hymenoptera
Hymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees and ants. There are over 130,000 recognized species, with many more remaining to be described. The name refers to the heavy wings of the insects, and is derived from the Ancient Greek ὑμήν : membrane and...
in quantity. These insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s contain among them many who can give painful stings, though the birds do not seem to mind. It may be that this species has elevated resistance to poison, as it readily eats scorpion
Scorpion
Scorpions are predatory arthropod animals of the order Scorpiones within the class Arachnida. They have eight legs and are easily recognized by the pair of grasping claws and the narrow, segmented tail, often carried in a characteristic forward curve over the back, ending with a venomous stinger...
s. But even small vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...
s like rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s, snake
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...
s, lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
s, and small bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s are eaten. Sometimes, Greater Rheas will gather at carrion
Carrion
Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
to feed on flies
Fly
True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...
; they are also known to eat dead or dying fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
in the dry season, but as vertebrate prey in general not in large quantities.
The natural predators of adult Greater Rheas are limited to the Cougar (Puma concolor) and the Jaguar
Jaguar
The jaguar is a big cat, a feline in the Panthera genus, and is the only Panthera species found in the Americas. The jaguar is the third-largest feline after the tiger and the lion, and the largest in the Western Hemisphere. The jaguar's present range extends from Southern United States and Mexico...
(Panthera onca). Feral dog
Feral
A feral organism is one that has changed from being domesticated to being wild or untamed. In the case of plants it is a movement from cultivated to uncultivated or controlled to volunteer. The introduction of feral animals or plants to their non-native regions, like any introduced species, may...
s are known to kill younger birds, and the Southern Caracara
Southern Caracara
The Southern Crested Caracara , also known as the Southern Caracara, is a bird of prey in the family Falconidae. It formerly included the Northern Caracara of the southern United States, Mexico, Central America and northern South America, and the extinct Guadalupe Caracara as subspecies...
(Caracara plancus) is suspected to prey on hatchlings. Armadillo
Armadillo
Armadillos are New World placental mammals, known for having a leathery armor shell. Dasypodidae is the only surviving family in the order Cingulata, part of the superorder Xenarthra along with the anteaters and sloths. The word armadillo is Spanish for "little armored one"...
s sometimes feed on Greater Rhea eggs; nests have been found which had been undermined by a Six-banded Armadillo
Six-banded Armadillo
The Six-banded Armadillo , also known as the Yellow Armadillo, is a species of armadillo from South America. It is found in Argentina, Bolivia, Brazil, Uruguay, Paraguay and isolated populations in Suriname . Its body is usually yellowish in color, sometimes tan or light reddish-brown...
(Euphractus sexcinctus) or a Big Hairy Armadillo
Big Hairy Armadillo
Chaetophractus villosus, commonly called the Big Hairy Armadillo is one of the largest and most numerous armadillos in South America. It lives from sea level to altitudes of up to 1,300 meters across the southern portion of South America and can be found in grasslands, forests, savannahs, and has...
(Chaetophractus villosus) and the rhea eggs were broken apart.
Captive-bred Greater Rheas exhibit significant ecological naïvete. This fearlessness renders them highly vulnerable to predators if the birds are released into the wild in reintroduction
Reintroduction
Reintroduction is the deliberate release of a species into the wild in zones formerly inhabited by said species but where it has disappeared from for a number of reasons, from captivity or relocated from other areas where the species still survives in...
projects. Classical conditioning
Classical conditioning
Classical conditioning is a form of conditioning that was first demonstrated by Ivan Pavlov...
of Greater Rhea juveniles against predator models can prevent this to some degree, but the personality type
Personality type
Personality type refers to the psychological classification of different types of individuals. Personality types are sometimes distinguished from personality traits, with the latter embodying a smaller grouping of behavioral tendencies. Types are sometimes said to involve qualitative differences...
of the birds—whether they are bold or shy—influences the success of such training. In 2006, a protocol was established for training Greater Rheas to avoid would-be predators, and for identifying the most cautious animals for release.
Reproduction
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
laid by a dozen females; each individual female's clutch
Clutch (eggs)
A clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...
numbers some 5–10 eggs. However, the average clutch size is 26 with 7 different females eggs.
Rhea eggs measure about 130 by 90 mm (5.1 by 3.5 in) and weigh 600 g (21.2 oz) on average; they are thus less than half the size of an ostrich
Ostrich
The Ostrich is one or two species of large flightless birds native to Africa, the only living member of the genus Struthio. Some analyses indicate that the Somali Ostrich may be better considered a full species apart from the Common Ostrich, but most taxonomists consider it to be a...
egg. Their shell is greenish-yellow when fresh but soon fades to dull cream when exposed to light. The nest is a simple shallow and wide scrape in a hidden location; males will drag sticks, grass, and leaves in the area surrounding the nest so it resembles a firebreak as wide as their neck can reach.
The incubation period is 29–43 days. All the eggs hatch within 36 hours of each other even though the eggs in one nest were laid perhaps as much as two weeks apart. As it seems, when the first young are ready to hatch they start a call resembling a pop-bottle rocket, even while still inside the egg, thus the hatching time is coordinated. Greater Rheas are half-grown about three months after hatching, and sexually mature by their 14th month.
Conservation status
The Greater Rhea is considered a Near ThreatenedNear Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
species according to the IUCN. The species is believed to be declining due to increased hunting and the conversion of central South American grasslands to farmland. The populations of Argentina and Uruguay are most seriously affected by the decline.
Farmers sometimes consider the Greater Rhea pests, because they will eat broad-leaved crop plants, such as cabbage
Cabbage
Cabbage is a popular cultivar of the species Brassica oleracea Linne of the Family Brassicaceae and is a leafy green vegetable...
, chard
Chard
Chard , is a leafy green vegetable often used in Mediterranean cooking. While the leaves are always green, chard stalks vary in color. Chard has been bred to have highly nutrious leaves at the expense of the root...
and bok choi. Where they occur as pests, farmers tend to hunt and kill Greater Rheas. The burning of crops in South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
has also contributed to their decline.
International trade in wild-caught Greater Rheas is restricted as per CITES Appendix II.
Rhea farming
This species is farmed in North AmericaNorth America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
and Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
similar to the Emu
Emu
The Emu Dromaius novaehollandiae) is the largest bird native to Australia and the only extant member of the genus Dromaius. It is the second-largest extant bird in the world by height, after its ratite relative, the ostrich. There are three subspecies of Emus in Australia...
and Ostrich
Ostrich
The Ostrich is one or two species of large flightless birds native to Africa, the only living member of the genus Struthio. Some analyses indicate that the Somali Ostrich may be better considered a full species apart from the Common Ostrich, but most taxonomists consider it to be a...
. The main products are meat
Meat
Meat is animal flesh that is used as food. Most often, this means the skeletal muscle and associated fat and other tissues, but it may also describe other edible tissues such as organs and offal...
and eggs
Egg (food)
Eggs are laid by females of many different species, including birds, reptiles, amphibians, and fish, and have probably been eaten by mankind for millennia. Bird and reptile eggs consist of a protective eggshell, albumen , and vitellus , contained within various thin membranes...
, but rhea oil is used for cosmetics and soaps and rhea leather
Leather
Leather is a durable and flexible material created via the tanning of putrescible animal rawhide and skin, primarily cattlehide. It can be produced through different manufacturing processes, ranging from cottage industry to heavy industry.-Forms:...
is also traded in quantity. Male Greater Rheas are very territorial during the breeding season. The infant chicks have high mortality in typical confinement farming situations, but under optimum free-range conditions chicks will reach adult size by their fifth month.
External links
- Rhea videos, photos and sounds on the Internet Bird Collection