A ratite () is any of a diverse group of

flightless Flightless birds are birds that through evolution lost the ability to fly. There are over 60 extant species, including the well known ratites (ostriches, emu, cassowaries, rheas, and kiwi) and penguins. The smallest flightless bird is the ...

, large, long-necked, and long-legged birds of the infraclass

Palaeognathae Palaeognathae (; ) is a infraclass of birds, called paleognaths, within the class Aves of the clade Archosauria. It is one of the two extant infraclasses of birds, the other being Neognathae, both of which form Neornithes. Palaeognathae contai ...

Kiwi Kiwi most commonly refers to: * Kiwi (bird), a flightless bird native to New Zealand * Kiwi (nickname), a nickname for New Zealanders * Kiwifruit, an edible berry * Kiwi dollar or New Zealand dollar, a unit of currency Kiwi or KIWI may also ref ...

, the exception, are much smaller and shorter-legged and are the only nocturnal extant ratites. The systematics of and relationships within the paleognath clade have been in flux. Previously, all the flightless members had been assigned to the order

Struthioniformes Struthioniformes is an order of birds with only a single extant family, Struthionidae, containing the ostriches. Several other extinct families are known, spanning across the Northern Hemisphere, from the Early Eocene to the early Pliocene, includ ...

, which is more recently regarded as containing only the

ostrich Ostriches are large flightless birds of the genus ''Struthio'' in the order Struthioniformes, part of the infra-class Palaeognathae, a diverse group of flightless birds also known as ratites that includes the emus, rheas, and kiwis. There ...

. The modern bird superorder Palaeognathae consists of ratites and the flighted

Neotropic The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In bioge ...

tinamou Tinamous () form an order of birds called Tinamiformes (), comprising a single family called Tinamidae (), divided into two distinct subfamilies, containing 46 species found in Mexico, Central America, and South America. The word "tinamou" come ...

s (compare to

Neognathae Neognathae (; ) is a infraclass of birds, called neognaths, within the class Aves of the clade Archosauria. Neognathae includes the majority of living birds; the exceptions being the tinamous and the flightless ratites, which belong instead to ...

). Unlike other flightless birds, the ratites have no

keel The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. As the laying down of the keel is the initial step in the construction of a ship, in Br ...

on their

sternum The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Sh ...

— hence the name, from the Latin ''ratis'' (

raft A raft is any flat structure for support or transportation over water. It is usually of basic design, characterized by the absence of a hull. Rafts are usually kept afloat by using any combination of buoyant materials such as wood, sealed barrels ...

, a vessel which has no keel - in contradistinction to extant flighted birds with a keel). Without this to anchor their wing muscles, they could not have flown even if they developed suitable wings. Ratites are a paraphyletic group; tinamous fall within them, and are the sister group of the extinct

moa Moa are extinct giant flightless birds native to New Zealand. The term has also come to be used for chicken in many Polynesian cultures and is found in the names of many chicken recipes, such as Kale moa and Moa Samoa. Moa or MOA may also refe ...

. This implies that flightlessness is a trait that evolved independently multiple times in different ratite lineages. Most parts of the former

supercontinent In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", which leav ...

Gondwana have ratites, or did have until the fairly recent past. So did Europe in the

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''pal ...

and

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

, from where the first flightless paleognaths are known. Ostriches were present in Asia as recently as the

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

, although the genus is thought to have originated in Africa. However, the ostrich order may have evolved in Eurasia. A recent study posits a Laurasian origin for the clade.

Geranoidid Geranoididae is a clade of extinct birds from the early to late Eocene and possibly early Oligocene of North America and Europe. These were mid-sized, long-legged flightless birds.Gerald Mayr (2009). Paleogene Fossil Birds Recent research shows t ...

s, which may have been ratites, existed in North America.

Species

Living forms

The African

is the largest living ratite. A large member of this species can be nearly tall, weigh as much as , and can outrun a horse. Of the living species, the Australian

emu The emu () (''Dromaius novaehollandiae'') is the second-tallest living bird after its ratite relative the ostrich. It is endemic to Australia where it is the largest native bird and the only extant member of the genus '' Dromaius''. The emu ...

is next in height, reaching up to tall and about . Like the ostrich, it is a fast-running, powerful bird of the open plains and

woodland A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the ''plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunlight and limited shade (se ...

s. Also native to Australia and the islands to the north are the three species of

cassowary Cassowaries ( tpi, muruk, id, kasuari) are flightless birds of the genus ''Casuarius'' in the order Casuariiformes. They are classified as ratites (flightless birds without a keel on their sternum bones) and are native to the tropical fore ...

. Shorter than an emu, but heavier and solidly built, cassowaries prefer thickly vegetated

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

forest. They can be dangerous when surprised or cornered because of their razor-sharp

talons A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or tarsus ...

. In

New Guinea New Guinea (; Hiri Motu Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is a language of Papua New Guinea, which is spoken in surrounding areas of Port Moresby (Capital of Papua New Guinea). It is a simplified version of ...

, cassowary eggs are brought back to villages and the chicks raised for eating as a much-prized delicacy, despite (or perhaps because of) the risk they pose to life and limb. They reach up to tall and weigh as much as

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

has two species of rhea, large fast-running birds of the

Pampas The Pampas (from the qu, pampa, meaning "plain") are fertile South American low grasslands that cover more than and include the Argentine provinces of Buenos Aires, La Pampa, Santa Fe, Entre Ríos, and Córdoba; all of Uruguay; and Brazi ...

. The larger American rhea grows to about tall and usually weighs . The smallest ratites are the five species of

kiwi Kiwi most commonly refers to: * Kiwi (bird), a flightless bird native to New Zealand * Kiwi (nickname), a nickname for New Zealanders * Kiwifruit, an edible berry * Kiwi dollar or New Zealand dollar, a unit of currency Kiwi or KIWI may also ref ...

from New Zealand. Kiwi are

chicken The chicken (''Gallus gallus domesticus'') is a domesticated junglefowl species, with attributes of wild species such as the grey and the Ceylon junglefowl that are originally from Southeastern Asia. Rooster or cock is a term for an adu ...

-sized, shy, and nocturnal. They nest in deep burrows and use a highly developed sense of smell to find small insects and grubs in the soil. Kiwi are notable for laying eggs that are very large in relation to their body size. A kiwi egg may equal 15 to 20 percent of the body mass of a female kiwi. The smallest species of kiwi is the

little spotted kiwi The little spotted kiwi or little grey kiwi (''Apteryx owenii'') is a small flightless bird in the kiwi family Apterygidae. It is the smallest species of all five kiwis, at about , about the size of a bantam. It is endemic to New Zealand, and i ...

, at and .

Holocene extinct forms

At least nine species of

lived in New Zealand before the arrival of humans, ranging from turkey-sized to the

giant moa The giant moa (''Dinornis'') is an extinct genus of birds belonging to the moa family. As with other moa, it was a member of the order Dinornithiformes. It was endemic to New Zealand. Two species of ''Dinornis'' are considered valid, the Nort ...

Dinornis robustus The South Island giant moa (''Dinornis robustus'') is an extinct moa from the genus ''Dinornis.'' Context The moa were ratites, flightless birds with a sternum without a keel. They also had a distinctive palate. The origin of these birds is b ...

'' with a height of and weighing about . They became extinct by A.D. 1400 due to hunting by

Māori Māori or Maori can refer to: Relating to the Māori people * Māori people of New Zealand, or members of that group * Māori language, the language of the Māori people of New Zealand * Māori culture * Cook Islanders, the Māori people of the C ...

settlers, who arrived around A.D. 1280. ''

Aepyornis maximus ''Aepyornis'' is a genus of aepyornithid, one of three genera of ratite birds endemic to Madagascar until their extinction sometime around 1000 CE. The species ''A. maximus'' weighed up to , and until recently was regarded as the largest known ...

'', the "elephant bird" of

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

, was the heaviest bird ever known. Although shorter than the tallest moa, a large ''A. maximus'' could weigh over and stand up to tall. Accompanying it were three other species of ''

Aepyornis ''Aepyornis'' is a genus of aepyornithid, one of three genera of ratite birds endemic to Madagascar until their extinction sometime around 1000 CE. The species ''A. maximus'' weighed up to , and until recently was regarded as the largest known ...

'' as well as three species of the smaller genus ''

Mullerornis ''Mullerornis'' is a genus of extinct elephant birds (Aepyornithidae) of Madagascar. Description ''Mullerornis'' is smaller than the more well-known '' Aepyornis''. A bone possibly belonging to ''Mullerornis'' has been radiocarbon dated to abo ...

''. All these species went into decline following the arrival of humans on Madagascar around 2,000 years ago, and were gone by the 17th or 18th century if not earlier.

Classification

There are two taxonomic approaches to ratite classification: one combines the groups as

families Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideal ...

in the order Struthioniformes, while the other supposes that the lineages evolved mostly independently and thus elevates the families to order rank (Rheiformes, Casuariformes etc.).

Evolution

The longstanding story of ratite evolution was that they share a common flightless ancestor that lived in Gondwana, whose descendants were isolated from each other by

continental drift Continental drift is the hypothesis that the Earth's continents have moved over geologic time relative to each other, thus appearing to have "drifted" across the ocean bed. The idea of continental drift has been subsumed into the science of pla ...

, which carried them to their present locations. Supporting this idea, some studies based on morphology, immunology and DNA sequencing reported that ratites are

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

. Cracraft's 1974 biogeographic vicariance hypothesis suggested that ancestral flightless paleognaths, the ancestors of ratites, were present and widespread in Gondwana during the Late Cretaceous. As the supercontinent fragmented due to

plate tectonics Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large ...

, they were carried by plate movements to their current positions and evolved into the species present today. The earliest known ratite fossils date to the

epoch about 56 million years ago (e.g., ''

Diogenornis ''Diogenornis'' is an extinct genus of ratites, that lived during the Early Eocene (Itaboraian to Casamayoran in the SALMA classification).paleognaths are known from several million years earlier, and the classification and membership of the Ratitae itself is uncertain. Some of the earliest ratites occur in Europe. Recent analyses of genetic variation between the ratites do not support this simple picture. The ratites may have diverged from one another too recently to share a common Gondwanan ancestor. Also, the Middle Eocene ratites such as ''

Palaeotis ''Palaeotis'' is a genus of paleognath birds from the middle Eocene epoch of central Europe. One species is known, ''Palaeotis weigelti''. The holotype specimen is a fossil tarsometatarsus and phalanx. Lambrect (1928) described it as an extinct ...

'' and ''

Remiornis ''Remiornis heberti'' is an extinct species of paleognath bird from the Paleocene of France. It is a species comparable in size to modern rheas, and possibly related to another European Paleogene ratite, ''Palaeotis ''Palaeotis'' is a genus ...

'' from Central Europe may imply that the "out-of-Gondwana" hypothesis is oversimplified. Molecular phylogenies of the ratites have generally placed ostriches in the basal position and among extant ratites, placed rheas in the second most basal position, with Australo-Pacific ratites splitting up last; they have also shown that both the latter groups are monophyletic. Early mitochondrial genetic studies that failed to make ostriches basal were apparently compromised by the combination of rapid early radiation of the group and long terminal branches. A morphological analysis that created a basal New Zealand clade has not been corroborated by molecular studies. A 2008 study of nuclear genes shows ostriches branching first, followed by rheas and tinamous, then kiwi splitting from emus and cassowaries. In more recent studies, moas and tinamous were shown to be sister groups, and elephant birds were shown to be most closely related to the New Zealand kiwi. Additional support for the latter relationship was obtained from morphological analysis. The finding that tinamous nest within this group, originally based on twenty nuclear genes and corroborated by a study using forty novel nuclear loci makes 'ratites'

polyphyletic A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of conver ...

rather than monophyletic. Since tinamous are weak fliers, this raises interesting questions about the evolution of flightlessness in this group. The branching of the tinamous within the ratite radiation suggests flightlessness evolved independently among ratites at least three times. More recent evidence suggests this happened at least six times, or once in each major ratite lineage. Re-evolution of flight in the tinamous would be an alternative explanation, but such a development is without precedent in avian history, while loss of flight is commonplace. By 2014, a mitochondrial DNA phylogeny including fossil members placed ostriches on the basal branch, followed by rheas, then a clade consisting of moas and tinamous, followed by the final two branches: a clade of emus plus cassowaries and one of elephant birds plus kiwis. Vicariant speciation based on the

plate tectonic Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te ...

split-up of Gondwana followed by continental drift would predict that the deepest phylogenetic split would be between African and all other ratites, followed by a split between South American and Australo-Pacific ratites, roughly as observed. However, the elephant bird–kiwi relation appears to require dispersal across oceans by flight, as apparently does the colonization of New Zealand by the moa and possibly the back-dispersal of tinamous to South America, if the latter occurred. The phylogeny as a whole suggests not only multiple independent origins of flightlessness, but also of gigantism (at least five times). Gigantism in birds tends to be insular; however, a ten-million-year-long window of opportunity for evolution of avian gigantism on continents may have existed following the extinction of the non-avian dinosaurs, in which ratites were able to fill vacant herbivorous niches before mammals attained large size. Some authorities, though, have been skeptical of the new findings and conclusions. Kiwi and tinamous are the only palaeognath lineages not to evolve gigantism, perhaps because of competitive exclusion by giant ratites already present on New Zealand and South America when they arrived or arose. The fact that New Zealand has been the only land mass to recently support two major lineages of flightless ratites may reflect the absence of native mammals, which allowed kiwi to occupy a mammal-like nocturnal

niche Niche may refer to: Science *Developmental niche, a concept for understanding the cultural context of child development *Ecological niche, a term describing the relational position of an organism's species *Niche differentiation, in ecology, the ...

. However, various other landmasses such as South America and Europe have supported multiple lineages of flightless ratites that evolved independently, undermining this competitive exclusion hypothesis. Most recently, studies on genetic and morphological divergence and fossil distribution show that paleognaths as a whole probably had an origin in the northern hemisphere. Early Cenozoic northern hemisphere paleognaths such as ''

Lithornis ''Lithornis'' is a genus of extinct paleognathous birds. Although ''Lithornis'' was able to fly well, their closest relatives are the extant tinamous (which are poor flyers) and ratites (which are flightless birds). Fossils of ''Lithornis'' a ...

'', '' Pseudocrypturus'', ''

Paracathartes ''Paracathartes'' is a genus of extinct bird from the Wasachtian horizon of lower Eocene Wyoming. One species, ''Paracathartes howardae'' has been described. It is a paleognathous bird, turkey-like in stature and size, that probably resembled ...

'' and ''

'' appear to be the most basal members of the clade. The various ratite lineages were probably descended from flying ancestors that independently colonised South America and Africa from the north, probably initially in South America. From South America they could have traveled overland to Australia via Antarctica, (by the same route marsupials are thought to have used to reach Australia) and then reached New Zealand and Madagascar via "sweepstakes" dispersals across the oceans. Gigantism would have evolved subsequent to trans-oceanic dispersals.

Loss of flight

Loss of flight allows birds to eliminate the costs of maintaining various flight-enabling adaptations like high

pectoral muscle Pectoral muscles (colloquially referred to as "pecs") are the muscles that connect the front of the human chest with the bones of the upper arm and shoulder. This region contains four muscles that provide movements to the upper limbs or ribs. P ...

mass, hollow bones and a light build, et cetera. The basal metabolic rate of flighted species is much higher than that of flightless terrestrial birds. But energetic efficiency can only help explain the loss of flight when the benefits of flying are not critical to survival. Research on flightless rails indicates the flightless condition evolved in the absence of predators. This shows flight to be generally necessary for survival and dispersal in birds. In apparent contradiction to this, many landmasses occupied by ratites are also inhabited by predatory mammals. However, the K–Pg extinction event created a window of time with large predators absent that may have allowed the ancestors of ratites to evolve flightlessness. They subsequently underwent selection for large size. One hypothesis suggests that as predation pressure decreases on islands with low raptor species richness and no mammalian predators, the need for large, powerful flight muscles that make for a quick escape decreases. Moreover, raptor species tend to become generalist predators on islands with low species richness, as opposed to specializing in the predation of birds. An increase in leg size compensates for a reduction in wing length in insular birds that have not lost flight by providing a longer lever to increase force generated during the thrust that initiates takeoff.

Description

Ratites in general have many physical characteristics in common, which are often not shared by the family Tinamidae, or tinamous. First, the breast muscles are underdeveloped. They do not have keeled

sterna ''Sterna'' is a genus of terns in the bird family Laridae. The genus used to encompass most "white" terns indiscriminately, but mtDNA sequence comparisons have recently determined that this arrangement is paraphyletic. It is now restricted to t ...

. Their wishbones (

furcula The (Latin for "little fork") or wishbone is a forked bone found in most birds and some species of non-avian dinosaurs, and is formed by the fusion of the two pink clavicles. In birds, its primary function is in the strengthening of the thoracic ...

e) are almost absent. They have a simplified wing skeletons and musculature. Their legs are stronger and do not have air chambers, except the

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...

s. Their tail and flight feathers have retrogressed or have become decorative plumes. They have no feather vanes, which means they do not need to oil their feathers, hence they have no

preen gland The uropygial gland, informally known as the preen gland or the oil gland, is a bilobed sebaceous gland possessed by the majority of birds used to distribute the gland's oil through the plumage by means of preening. It is located dorsally at the ...

s. They have no separation of pterylae (feathered areas) and apteria (non-feathered areas), and finally, they have

palaeognath Palaeognathae (; ) is a infraclass of birds, called paleognaths, within the class Aves of the clade Archosauria. It is one of the two extant infraclasses of birds, the other being Neognathae, both of which form Neornithes. Palaeognathae co ...

ous

palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly separ ...

s. Ostriches have the greatest dimorphism, rheas show some

dichromatism Dichromatism (or polychromatism) is a phenomenon where a material or solution's hue is dependent on both the concentration of the absorbing substance and the depth or thickness of the medium traversed. In most substances which are not dichromatic, ...

during the breeding season. Emus, cassowaries, and kiwis show some dimorphism, predominantly in size. While the ratites share a lot of similarities, they also have major differences. Ostriches have only two toes, with one being much larger than the other. Cassowaries have developed long inner toenails, used defensively. Ostriches and rheas have prominent wings; although they don't use them to fly, they do use them in courtship and predator distraction. Without exception, ratite chicks are capable of swimming and even diving. On an

allometric Allometry is the study of the relationship of body size to shape, anatomy, physiology and finally behaviour, first outlined by Otto Snell in 1892, by D'Arcy Thompson in 1917 in ''On Growth and Form'' and by Julian Huxley in 1932. Overview Allome ...

basis,

paleognath Palaeognathae (; ) is a infraclass of birds, called paleognaths, within the class Aves of the clade Archosauria. It is one of the two extant infraclasses of birds, the other being Neognathae, both of which form Neornithes. Palaeognathae contain ...

s have generally smaller brains than

neognath Neognathae (; ) is a infraclass of birds, called neognaths, within the class Aves of the clade Archosauria. Neognathae includes the majority of living birds; the exceptions being the tinamous and the flightless ratites, which belong instead to t ...

s. Kiwis are exceptions to this trend, and possess proportionally larger brains comparable to those of

parrots Parrots, also known as psittacines (), are birds of the roughly 398 species in 92 genera comprising the order Psittaciformes (), found mostly in tropical and subtropical regions. The order is subdivided into three superfamilies: the Psittacoide ...

and

songbirds A songbird is a bird belonging to the suborder Passeri of the perching birds (Passeriformes). Another name that is sometimes seen as the scientific or vernacular name is Oscines, from Latin ''oscen'', "songbird". The Passeriformes contains 5 ...

, though evidence for similar advanced cognitive skills is currently lacking.

Gallery of living species

Image:Autruche Thoiry 19801.jpg,

Ostrich Ostriches are large flightless birds of the genus ''Struthio'' in the order Struthioniformes, part of the infra-class Palaeognathae, a diverse group of flightless birds also known as ratites that includes the emus, rheas, and kiwis. There ...

Image:Masai Ostriches Benh.jpg, Ostrich herd (''S. camelus massaicus'') Image:Rhea side profile.jpg, American rhea Image:Darwin-Nandus.jpg,

Darwin's rhea Darwin's rhea or the lesser rhea (''Rhea pennata'') is a large flightless bird, the smaller of the two extant species of rheas. It is found in the Altiplano and Patagonia in South America. Description The lesser rhea stands at tall. Lengt ...

Image:Double-wattled Cassowary.jpg,

Southern cassowary The southern cassowary (''Casuarius casuarius''), also known as double-wattled cassowary, Australian cassowary or two-wattled cassowary, is a large flightless black bird. It is one of the three living species of cassowary, alongside the dwarf c ...

File:Casuarius unappendiculatus -Northern Cassowary -head to toe.jpg,

Northern cassowary The northern cassowary (''Casuarius unappendiculatus'') also known as the one-wattled cassowary, single-wattled cassowary, or golden-necked cassowary, is a large, stocky flightless bird of northern New Guinea. It is one of the three living spec ...

Image:Mooruk-Wolf.jpg,

Dwarf cassowary The dwarf cassowary (''Casuarius bennetti''), also known as Bennett's cassowary, little cassowary, mountain cassowary or muruk, is the smallest of the three species of cassowaries. Taxonomy The scientific name commemorates the Australian natura ...

File:Dromaius novaehollandiae qtl1.jpg,

Emu The emu () (''Dromaius novaehollandiae'') is the second-tallest living bird after its ratite relative the ostrich. It is endemic to Australia where it is the largest native bird and the only extant member of the genus '' Dromaius''. The emu ...

Image:Apteryx haastii.jpg,

Great spotted kiwi The great spotted kiwi, great grey kiwiDavies, S. J. J. F. (2003) or roroa (''Apteryx haastii'') is a species of kiwi endemic to the South Island of New Zealand. The great spotted kiwi, as a member of the ratites, is flightless. It is the larg ...

Image:Apteryx owenii 0.jpg,

Little spotted kiwi The little spotted kiwi or little grey kiwi (''Apteryx owenii'') is a small flightless bird in the kiwi family Apterygidae. It is the smallest species of all five kiwis, at about , about the size of a bantam. It is endemic to New Zealand, and i ...

Image:Kiwifugl.jpg,

North Island brown kiwi The North Island brown kiwi (''Apteryx mantelli''; ''Apteryx australis'' or ''Apteryx bulleri'' as before 2000, still used in some sources) is a species of kiwi that is widespread in the northern two-thirds of the North Island of New Zealand an ...

Behavior and ecology

Feeding and diet

Ratite chicks tend to be more

omnivorous An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nut ...

or insectivorous; similarities in adults end with feeding, as they all vary in diet and length of digestive tract, which is indicative of diet. Ostriches, with the longest tracts at , are primarily

herbivorous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...

. Rheas' tracts are next longest at , and they also have caeca. They are also mainly

herbivores A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...

, concentrating on broad-leafed plants. However, they will eat insects if the opportunity arises. Emus have tracts of length, and have a more omnivorous diet, including insects and other small animals. Cassowaries have next to the shortest tracts at . Finally, kiwi have the shortest tracts and eat earthworms, insects, and other similar creatures. Moas and

elephant birds Elephant birds are members of the Extinction, extinct ratite family (biology), family Aepyornithidae, made up of flightless birds that once lived on the island of Madagascar. They are thought to have become extinct around 1000-1200 CE, probably ...

were the largest native herbivores in their faunas, far larger than contemporary herbivorous mammals in the latter's case. Some extinct ratites might have had odder lifestyles, such as the narrow-billed ''

Diogenornis ''Diogenornis'' is an extinct genus of ratites, that lived during the Early Eocene (Itaboraian to Casamayoran in the SALMA classification).Palaeotis ''Palaeotis'' is a genus of paleognath birds from the middle Eocene epoch of central Europe. One species is known, ''Palaeotis weigelti''. The holotype specimen is a fossil tarsometatarsus and phalanx. Lambrect (1928) described it as an extinct ...

'', compared to the shorebird-like

lithornithids Lithornithidae is an extinct, possibly paraphyletic (but see below) group of early paleognath birds. They are known from fossils dating to the Upper Paleocene through the Middle Eocene of North America and Europe, with possible Late Cretaceous r ...

, and could imply similar animalivorous diets.

Reproduction

Ratites are different from the flying birds in that they needed to adapt or evolve certain features to protect their young. First and foremost is the thickness of the shells of their eggs. Their young are hatched more developed than most and they can run or walk soon thereafter. Also, most ratites have communal nests, where they share the incubating duties with others. Ostriches, and great spotted kiwis, are the only ratites where the female incubates; they share the duties, with the males incubating at night. Cassowaries and emu are polyandrous, with males incubating eggs and rearing chicks with no obvious contribution from females. Ostriches and rheas are polygynous with each male courting several females. Male rheas are responsible for building nests and incubating while ostrich males incubate only at night. Kiwis stand out as the exception with extended monogamous reproductive strategies where either the male alone or both sexes incubate a single egg.

Ratites and humans

Ratites and humans have had a long relationship starting with the use of the egg for water containers, jewelry, or other art medium. Male ostrich feathers were popular for hats during the 18th century, which led to hunting and sharp declines in populations. Ostrich farming grew out of this need, and humans harvested feathers, hides, eggs, and meat from the ostrich. Emu farming also became popular for similar reasons and for their

emu oil Emu oil is an oil derived from body fat harvested from certain subspecies of the emu, ''Dromaius novaehollandiae'', a flightless bird indigenous to Australia. Unadulterated emu oil can vary widely in colour and viscosity anywhere from an off-w ...

. Rhea feathers are popular for dusters, and eggs and meat are used for chicken and pet feed in South America. Ratite hides are popular for leather products like shoes.

United States regulation

The USDA's

Food Safety and Inspection Service The Food Safety and Inspection Service (FSIS), an agency of the United States Department of Agriculture (USDA), is the public health regulatory agency responsible for ensuring that United States' commercial supply of meat, poultry, and egg pro ...

(FSIS) began a voluntary, fee-for-service ratite inspection program in 1995 to help the fledgling industry improve the marketability of the meat. A provision in the FY2001 USDA appropriations act (P.L. 106–387) amended the

Poultry Products Inspection Act The Poultry Products Inspection Act of 1957 ( P.L. 85–172, as amended) requires the United States Department of Agriculture's Food Safety and Inspection Service (FSIS) to inspect all domesticated birds when slaughtered and processed into products ...

to make federal inspection of ratite meat mandatory as of April 2001 (21 U.S.C. 451 et seq.).

References

External links

Websites With Information On Ratites
{{Taxonbar, from=Q19170 Flightless birds Extant Thanetian first appearances Taxa named by William Plane Pycraft Paraphyletic groups