The Réunion ibis or Réunion sacred ibis (''Threskiornis solitarius'') is an
extinct
Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...
species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
of
ibis
The ibis () (collective plural ibises; classical plurals ibides and ibes) are a group of long-legged wading birds in the family Threskiornithidae that inhabit wetlands, forests and plains. "Ibis" derives from the Latin and Ancient Greek word f ...
that was
endemic
Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
to the volcanic island of
Réunion
Réunion (; ; ; known as before 1848) is an island in the Indian Ocean that is an overseas departments and regions of France, overseas department and region of France. Part of the Mascarene Islands, it is located approximately east of the isl ...
in the
Indian Ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...
. The first
subfossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
remains were found in 1974, and the ibis was first scientifically described in 1987. Its closest relatives are the
Malagasy sacred ibis, the
African sacred ibis, and the
straw-necked ibis. Travellers' accounts from the 17th and 18th centuries described a white bird on Réunion that flew with difficulty and preferred solitude, which was subsequently referred to as the "Réunion solitaire".
In the mid 19th century, the old travellers' accounts were incorrectly assumed to refer to white relatives of the
dodo
The dodo (''Raphus cucullatus'') is an extinction, extinct flightless bird that was endemism, endemic to the island of Mauritius, which is east of Madagascar in the Indian Ocean. The dodo's closest relative was the also-extinct and flightles ...
, due to one account specifically mentioning dodos on the island, and because 17th-century paintings of white dodos had recently surfaced. However, no fossils referable to dodo-like birds were ever found on Réunion, and it was later questioned whether the paintings had anything to do with the island. Other identities were suggested as well, based only on speculations. In the late 20th century, the discovery of ibis
subfossils led to the idea that the old accounts actually referred to an ibis species instead. The idea that the "solitaire" and the subfossil ibis are identical was met with limited dissent, but is now widely accepted.
Combined, the old descriptions and subfossils show that the Réunion ibis was mainly white, with this colour merging into yellow and grey. The wing tips and plumes of
ostrich
Ostriches are large flightless birds. Two living species are recognised, the common ostrich, native to large parts of sub-Saharan Africa, and the Somali ostrich, native to the Horn of Africa.
They are the heaviest and largest living birds, w ...
-like feathers on its rear were black. The neck and legs were long, and the beak was relatively straight and short for an ibis. It was more robust in build than its extant relatives, but was otherwise quite similar to them. It would have been no longer than 65 cm (25 in) in length. Subfossil wingbones indicate it had reduced flight capabilities, a feature perhaps linked to seasonal fattening. The diet of the Réunion ibis was worms and other items foraged from the soil. In the 17th century, it lived in mountainous areas, but it may have been confined to these remote heights by heavy hunting by humans and predation by
introduced animals in the more accessible areas of the island. Visitors to Réunion praised its flavour, and therefore sought after its flesh. These factors are believed to have driven the Réunion ibis to extinction by the early 18th century.
Taxonomy
The taxonomic history of the Réunion ibis is convoluted and complex, due to the ambiguous and meagre evidence that was available to scientists until the late 20th century. The supposed "white dodo" of Réunion is now believed to have been an erroneous conjecture based on the few contemporary reports which described the Réunion ibis, combined with paintings of white dodos from Mauritius by the
Dutch painters
Pieter Withoos and
Pieter Holsteyn II (and derivatives) from the 17th century that surfaced in the 19th century.
The English Chief Officer John Tatton was the first to mention a specifically white bird on Réunion, in 1625. The French occupied the island from 1646 and onwards, and referred to this bird as the "solitaire". M. Carré of the
French East India Company described the "solitaire" in 1699, explaining the reason for its name:
The
marooned French
Huguenot
The Huguenots ( , ; ) are a Religious denomination, religious group of French people, French Protestants who held to the Reformed (Calvinist) tradition of Protestantism. The term, which may be derived from the name of a Swiss political leader, ...
François Leguat used the name "solitaire" for the
Rodrigues solitaire
The Rodrigues solitaire (''Pezophaps solitaria'') is an extinct flightless bird that was endemism, endemic to the island of Rodrigues, east of Madagascar in the Indian Ocean. Genetically within the family of Columbidae, pigeons and doves, it wa ...
, a
Raphine bird (related to the dodo) he encountered on the nearby island of
Rodrigues in the 1690s, but it is thought he borrowed the name from a 1689
tract by Marquis Henri Duquesne which mentioned the Réunion species. Duquesne himself had probably based his own description on an earlier one.
No specimens of the "solitaire" were ever preserved.
The two individuals Carré attempted to send to the
royal menagerie in France did not survive in captivity. Billiard claimed that the French administrator
Bertrand-François Mahé de La Bourdonnais sent a "solitaire" to France from Réunion around 1740. Since the Réunion ibis is believed to have gone extinct by this date, the bird may actually have been a Rodrigues solitaire.
The only contemporary writer who referred specifically to "dodos" inhabiting
Réunion
Réunion (; ; ; known as before 1848) is an island in the Indian Ocean that is an overseas departments and regions of France, overseas department and region of France. Part of the Mascarene Islands, it is located approximately east of the isl ...
was the Dutch sailor
Willem Ysbrandtszoon Bontekoe, though he did not mention their colouration:
When his journal was published in 1646, it was accompanied by an engraving which is now known to have been copied after one of the dodos in the
Flemish painter
Roelant Savery
Roelant Savery (or ''Roeland(t) Maertensz Saverij'', or ''de Savery'', or many variants; 1576 – buried 25 February 1639) was a Flanders-born Dutch Golden Age painter.
Life
Savery was born in Kortrijk. Like so many other artists, he belonged ...
's "Crocker Art Gallery sketch".
Since Bontekoe was
shipwreck
A shipwreck is the wreckage of a ship that is located either beached on land or sunken to the bottom of a body of water. It results from the event of ''shipwrecking'', which may be intentional or unintentional. There were approximately thre ...
ed and lost all his belongings after visiting Réunion in 1619, he may not have written his account until he returned to
Holland
Holland is a geographical regionG. Geerts & H. Heestermans, 1981, ''Groot Woordenboek der Nederlandse Taal. Deel I'', Van Dale Lexicografie, Utrecht, p 1105 and former provinces of the Netherlands, province on the western coast of the Netherland ...
, seven years later, which would put its reliability in question.
He may have concluded in hindsight that it was a dodo, finding what he saw similar to accounts of that bird.
Early interpretation
In the 1770s, the French naturalist
Comte de Buffon
Georges-Louis Leclerc, Comte de Buffon (; 7 September 1707 – 16 April 1788) was a French naturalist, mathematician, and cosmologist. He held the position of ''intendant'' (director) at the ''Jardin du Roi'', now called the Jardin des plant ...
stated that the dodo inhabited both
Mauritius
Mauritius, officially the Republic of Mauritius, is an island country in the Indian Ocean, about off the southeastern coast of East Africa, east of Madagascar. It includes the main island (also called Mauritius), as well as Rodrigues, Ag ...
and Réunion for unclear reasons. He also combined accounts about the Rodrigues solitaire and a bird from Mauritius ("oiseau de Nazareth", now thought to be a dodo), as well as the "solitaire" Carré reported from Réunion under one "solitaire" section, indicating he believed there was both a dodo and "solitaire" on Réunion.
The English naturalist
Hugh Edwin Strickland
Hugh Edwin Strickland (2 March 1811 – 14 September 1853) was an English geologist, ornithology, ornithologist, naturalist and systematist. Through the British Association, he proposed a series of rules for the nomenclature of organisms in zool ...
discussed the old descriptions of the "solitaire" in his 1848 book ''The Dodo and Its Kindred'', and concluded it was distinct from the dodo and Rodrigues solitaire due to its colouration.
The Belgian scientist
Edmond de Sélys Longchamps
Baron Michel Edmond de Selys Longchamps (25 May 1813 – 11 December 1900) was a Belgium, Belgian Liberal Party (Belgium), Liberal Party politician and scientist. Selys Longchamps has been regarded as the founding figure of odonatology, the stud ...
coined the
scientific name
In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...
''Apterornis solitarius'' for the "solitaire" in 1848, apparently making it the
type species
In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...
of the genus, in which he also included two other
Mascarene
The Mascarene Islands (, ) or Mascarenes or Mascarenhas Archipelago is a group of islands in the Indian Ocean east of Madagascar consisting of islands belonging to the Republic of Mauritius as well as the French department of Réunion. Their na ...
birds only known from contemporary accounts, the
red rail and the
Réunion swamphen.
As the name ''
Apterornis'' had already been used for a different bird by the English biologist
Richard Owen
Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomy, comparative anatomist and paleontology, palaeontologist. Owen is generally considered to have been an outstanding naturalist with a remarkabl ...
, and the other former names were likewise invalid, Bonaparte coined the new
binomial ''Ornithaptera borbonica'' in 1854 (
Bourbon was the original French name for Réunion).
In 1854, the German ornithologist
Hermann Schlegel
Hermann Schlegel (10 June 1804 – 17 January 1884) was a German ornithologist, herpetologist and ichthyologist.
Early life and education
Schlegel was born at Altenburg, the son of a brassfounder. His father collected butterflies, which stimulated ...
placed the "solitaire" in the same genus as the dodo, and named it ''Didus apterornis''. He restored it strictly according to contemporary accounts, which resulted in an
ibis
The ibis () (collective plural ibises; classical plurals ibides and ibes) are a group of long-legged wading birds in the family Threskiornithidae that inhabit wetlands, forests and plains. "Ibis" derives from the Latin and Ancient Greek word f ...
or
stork
Storks are large, long-legged, long-necked wading birds with long, stout bills. They belong to the family Ciconiidae, and make up the order Ciconiiformes . Ciconiiformes previously included a number of other families, such as herons and ibise ...
-like bird instead of a dodo.
In 1856, William Coker announced the discovery of a 17th-century "
Persia
Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the nort ...
n" painting of a white dodo among
waterfowl
Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which i ...
, which he had been shown in England. The artist was later identified as Pieter Withoos, and many prominent 19th-century naturalists subsequently assumed the image depicted the white "solitaire" of Réunion, a possibility originally proposed by ornithologist
John Gould
John Gould (; 14 September 1804 – 3 February 1881) was an English ornithologist who published monographs on birds, illustrated by plates produced by his wife, Elizabeth Gould (illustrator), Elizabeth Gould, and several other artists, includ ...
. Simultaneously, several similar paintings of white dodos by Pieter Holsteyn II were discovered in the Netherlands.
Other paintings and drawings were also later identified as showing white dodos.
In 1869, the English ornithologist
Alfred Newton
Alfred Newton Fellow of the Royal Society, FRS HFRSE (11 June 18297 June 1907) was an England, English zoologist and ornithologist. Newton was Professor of Comparative Anatomy at Cambridge University from 1866 to 1907. Among his numerous public ...
argued that the Withoos' painting and engraving in Bontekoe's memoir depicted a living Réunion dodo that had been brought to Holland, while explaining its blunt beak as a result of
beak trimming to prevent it from injuring humans. He also brushed aside the inconsistencies between the illustrations and descriptions, especially the long, thin beak implied by one contemporary account.
Newton's words particularly cemented the validity of this connection among contemporary peers, and several of them expanded on his views.
The Dutch zoologist
Anthonie Cornelis Oudemans suggested in 1917 that the discrepancies between the paintings and the old descriptions were due to the paintings showing a female, and that the species was, therefore,
sexually dimorphic
Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...
.
The British zoologist
Walter Rothschild claimed in 1907 that the yellow wings might have been due to
albinism
Albinism is the congenital absence of melanin in an animal or plant resulting in white hair, feathers, scales and skin and reddish pink or blue eyes. Individuals with the condition are referred to as albinos.
Varied use and interpretation of ...
in this particular specimen, since the old descriptions described these as black.
By the early 20th century, many other paintings and even physical remains were claimed to be of white dodos, amid much speculation.
Rothschild commissioned British artist
Frederick William Frohawk to restore the "solitaire" as both a white dodo, based on the Withoos painting, and as a distinct bird based on the French traveller
Sieur Dubois' 1674 description, for his 1907 book ''
Extinct Birds''.
In 1937, the Japanese writer
Masauji Hachisuka suggested that the old accounts and paintings represented two different species, and referred to the white dodos of the paintings as ''Victoriornis imperialis'' (honouring King
Victor Emmanuel III of Italy
Victor Emmanuel III (; 11 November 1869 – 28 December 1947) was King of Italy from 29 July 1900 until his abdication on 9 May 1946. A member of the House of Savoy, he also reigned as Emperor of Ethiopia from 1936 to 1941 and King of the Albania ...
), and the "solitaire" of the accounts as ''Ornithaptera solitarius'' (using the generic name coined by Bonaparte).
Hachisuka also suggested that a 1618 Italian illustration previously identified as a dodo being hunted, actually showed a male, brown Réunion solitaire (he ruled out Rodrigues because that island was not yet inhabited at the time). To him, this cleared up the confusion between the two species, which is why he named the white dodo for the King of Italy (the illustration being from Italy). Today the illustration is thought to depict an
ostrich
Ostriches are large flightless birds. Two living species are recognised, the common ostrich, native to large parts of sub-Saharan Africa, and the Somali ostrich, native to the Horn of Africa.
They are the heaviest and largest living birds, w ...
or a
bustard.
Modern interpretation

Until the late 1980s, belief in the existence of a white dodo on Réunion was the orthodox view, and only a few researchers doubted the connection between the "solitaire" accounts and the dodo paintings. The American ornithologist
James Greenway cautioned in 1958 that no conclusions could be made without solid evidence such as fossils, and that nothing indicated that the white dodos in the paintings had anything to do with Réunion. In 1970, the American ornithologist
Robert W. Storer predicted that if any such remains were found, they would not belong to Raphinae like the dodo and Rodrigues solitaire (or even to the
pigeon
Columbidae is a bird family consisting of doves and pigeons. It is the only family in the order Columbiformes. These are stout-bodied birds with small heads, relatively short necks and slender bills that in some species feature fleshy ceres. ...
family like them).
The first subfossil bird remains on Réunion, the lower part of a
tarsometatarsus
The tarsometatarsus is a bone that is only found in the lower leg of birds and some non-avian dinosaurs. It is formed from the fusion of several bird bones found in other types of animals, and homologous to the mammalian tarsus (ankle bones) a ...
, was found in 1974, and considered a new species of stork in the genus ''
Ciconia'' by the British ornithologist
Graham S. Cowles in 1987. The remains were found in a cave, which indicated it had been brought there and eaten by early settlers. It was speculated that the remains could have belonged to a large, mysterious bird described by Leguat, and called "Leguat's giant" by some ornithologists. "Leguat's giant" is now thought to be based on a locally extinct population of
greater flamingos.
Also in 1987, a subfossil tarsometatarsus of an ibis found in a cave was described as ''Borbonibis latipes'' (the
specific name means "wide foot") by the French palaeontologists Cécile Mourer-Chauviré and François Moutou, and thought related to the
bald ibises of the genus ''Geronticus''.
In 1994, Cowles concluded that the "stork" remains he had reported belonged to ''Borbonibis'', since their tarsometatarsi were similar.
The 1987 discovery led the English biologist Anthony S. Cheke to suggest to one of the describers of ''Borbonibis'' that the subfossils may have been of the "solitaire".
In 1995, the French ecologist Jean-Michel Probst reported his discovery of a bird mandible during an excavation on Réunion the former year, and suggested it may have belonged to the ibis or the "solitaire".
In 1995, the describers of ''Borbonibis latipes'' suggested that it represented the "Réunion solitaire", and reassigned it to the ibis genus ''
Threskiornis'', now combined with the specific name ' from de Sélys-Longchamps' 1848 binomial for the "solitaire" (making ''Borbonibis latipes'' a
junior synonym
In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently.
...
). The authors pointed out that the contemporary descriptions matched the appearance and behaviour of an ibis more than a member of the Raphinae, especially due to its comparatively short and straight mandible, and because ibis remains were abundant in some localities; it would be strange if contemporary writers never mentioned such a relatively common bird, whereas they mentioned most other species subsequently known from fossils.

The possible origin of the 17th-century white dodo paintings was examined, by the Spanish biologist Arturo Valledor de Lozoya in 2003, and independently by experts of Mascarene fauna Cheke and
Julian Hume in 2004. The Withoos and Holsteyn paintings are clearly derived from each other, and Withoos likely copied his dodo from one of Holsteyn's works, since these were probably produced at an earlier date. All later white dodo pictures are thought to be based on these paintings. According to the aforementioned writers, it appears these pictures were themselves derived from a whitish dodo in a previously unreported painting called ''Landscape with Orpheus and the Animals'', produced by Roelant Savery c. 1611. The dodo was apparently based on a stuffed specimen then in
Prague
Prague ( ; ) is the capital and List of cities and towns in the Czech Republic, largest city of the Czech Republic and the historical capital of Bohemia. Prague, located on the Vltava River, has a population of about 1.4 million, while its P ...
; a ''walghvogel'' (old Dutch for dodo) described as having a "dirty off-white colouring" was mentioned in an inventory of specimens in the Prague collection of the
Holy Roman Emperor Rudolf II to whom Savery was contracted at the time (1607–1611).
Savery's several later dodo images all show greyish birds, possibly because he had by then seen a normal specimen. Cheke and Hume concluded the painted specimen was white due to albinism, and that this peculiar feature was the reason it was collected from Mauritius and brought to Europe.
Valledor de Lozoya instead suggested that the light plumage was a juvenile trait, a result of bleaching of old taxidermy specimens, or simply due to artistic license.
In 2018, the British ornithologist Jolyon C. Parish and Cheke suggested that the painting was instead executed after 1614, or even after 1626, based on some of the motifs.
While many subfossil elements from throughout the skeleton have been assigned to the Réunion ibis, no remains of dodo-like birds have ever been found on Réunion.
A few later sources have taken issue with the proposed ibis-identity of the "solitaire", and have even regarded the "white dodo" as a valid species.
The British writer
Errol Fuller agrees that the 17th-century paintings do not depict Réunion birds, but has questioned whether the ibis subfossils are necessarily connected to the "solitaire" accounts. He notes that no evidence indicates the extinct ibis survived until the time Europeans reached Réunion.
Cheke and Hume have dismissed such sentiments as being mere "belief" and "hope" in the existence of a dodo on the island.
Evolution
The volcanic island of Réunion is only three million years old, whereas Mauritius and Rodrigues, with each of their flightless Raphine species, are eight to ten million years old, and according to Cheke and Hume it is unlikely that either bird would have been capable of flying after five or more million years of adapting to the islands. Therefore, it is unlikely that Réunion could have been colonised by flightless birds from these islands, and only flighted species on the island have relatives there.
Three million years is enough time for flightless and weak flying abilities to have evolved in bird species on Réunion itself, but Mourer-Chauviré and colleagues pointed out that such species would have been wiped out by the eruption of the
volcano
A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
On Earth, volcanoes are most oft ...
Piton des Neiges between 300,000 and 180,000 years ago. Most recent species would therefore likely be descendants of animals which had recolonised the island from Africa or Madagascar after this event, which is not enough time for a bird to become flightless.
In 1995, a morphological study by Mourer-Chauviré and colleagues suggested the closest extant relatives of the Réunion ibis are the
African sacred ibis (''T. aethiopicus'') of Africa and the
straw-necked ibis (''T. spinicollis'') of Australia.
Cheke and Hume instead suggested that it was closest to the
Malagasy sacred ibis (''T. bernieri''), and therefore of ultimately African origin.
Description
Contemporary accounts described the species as having white and grey plumage merging into yellow, black wing tips and tail feathers, a long neck and legs, and limited flight capabilities.
Dubois' 1674 account is the most detailed contemporary description of the bird,
here as translated by Strickland in 1848:
According to Mourer-Chauviré and colleagues, the plumage colouration mentioned is similar to that of the related African sacred ibis and straw-necked ibis, which are also mainly white and glossy black. In the reproductive season, the ornamental feathers on the back and wing tips of the African sacred ibis look similar to the feathers of an ostrich, which echoes Dubois' description. Likewise, a subfossil lower jaw found in 1994 showed that the bill of the Réunion ibis was relatively short and straight for an ibis, which corresponds with Dubois'
woodcock
The woodcocks are a group of seven or eight very similar living species of sandpipers in the genus ''Scolopax''. The genus name is Latin for a snipe or woodcock, and until around 1800 was used to refer to a variety of waders. The English name ...
comparison.
Cheke and Hume have suggested that the French word (''bécasse'') from Dubois' original description, usually translated to "woodcock", could also mean
oystercatcher
The oystercatchers are a group of waders forming the family (biology), family Haematopodidae, which has a single genus, ''Haematopus''. They are found on coasts worldwide apart from the polar regions and some tropical regions of Africa and Sout ...
, another bird with a long, straight, but slightly more robust, bill. They have also pointed out that the last sentence is mistranslated, and actually means the bird could be caught by running after it.
The bright colouration of the plumage mentioned by some authors may refer to
iridescence
Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear gradually to change colour as the angle of view or the angle of illumination changes. Iridescence is caused by wave interference of light in microstru ...
, as seen in the straw-necked ibis.
Subfossils of the Réunion ibis show that it was more robust, likely much heavier, and had a larger head than the African sacred and straw-necked ibises. It was nonetheless similar to them in most features. According to Hume, it would have been no longer than 65 cm (25 in) in length, the size of the African sacred ibis. Rough protuberances on the wing bones of the Réunion ibis are similar to those of birds that use their wings in combat. It was perhaps flightless, but this has not left significant
osteological traces; no complete skeletons have been collected, but of the known
pectoral elements, only one feature indicates reduction in flight capability. The
coracoid
A coracoid is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is present as part of the scapula, but this is n ...
is elongated and the
radius
In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...
and
ulna
The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...
are robust, as in flighted birds, but a particular
foramen
In anatomy and osteology, a foramen (; : foramina, or foramens ; ) is an opening or enclosed gap within the dense connective tissue (bones and deep fasciae) of extant and extinct amniote animals, typically to allow passage of nerves, artery, ...
(or opening) between a
metacarpal
In human anatomy, the metacarpal bones or metacarpus, also known as the "palm bones", are the appendicular bones that form the intermediate part of the hand between the phalanges (fingers) and the carpal bones ( wrist bones), which articulate ...
and the
alular is otherwise only known from flightless birds, such as some
ratites
Ratites () are a polyphyletic group consisting of all birds within the infraclass Palaeognathae that lack keel (bird anatomy), keels and flightless bird, cannot fly. They are mostly large, long-necked, and long-legged, the exception being the Kiw ...
,
penguins, and several extinct species.
Behaviour and ecology
As contemporary accounts are inconsistent on whether the "solitaire" was flightless or had some flight capability, Mourer-Chauvire and colleagues suggested that this was dependent on seasonal fat-cycles, meaning that individuals fattened themselves during cool seasons, but were slim during hot seasons; perhaps it could not fly when it was fat, but could when it was not.
However, Dubois specifically stated the "solitaires" did not have fat-cycles, unlike most other Réunion birds.
The only mention of its diet and exact habitat is the account of the French cartographer
Jean Feuilley from 1708, which is also the last record of a living individual:
The diet and mode of
foraging
Foraging is searching for wild food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce. Foraging theory is a branch of behavioral ecology that studies the foraging behavi ...
described by Feuilley matches that of an ibis, whereas members of the Raphinae are known to have been
fruit eaters.
The species was termed a land-bird by Dubois, so it did not live in typical ibis habitats such as
wetlands
A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally. Flooding results in oxygen-poor ( anoxic) processes taking place, especially ...
. This is similar to the Réunion swamphen, which lived in forest rather than swamps, which is otherwise typical
swamphen habitat. Cheke and Hume proposed that the ancestors of these birds colonised Réunion before swamps had developed, and had therefore become adapted to the available habitats. They were perhaps prevented from colonising Mauritius as well due to the presence of red rails there, which may have occupied a similar niche.
The Réunion ibis appears to have lived in high altitudes, and perhaps had a limited distribution.
Accounts by early visitors indicate the species was found near their landing sites, but they were found only in remote places by 1667. The bird may have survived in eastern lowlands until the 1670s. Though many late 17th century accounts state the bird was good food, Feuilley stated it tasted bad. This may be because it changed its diet when it moved to more rugged, higher terrain, to escape pigs that destroyed its nests; since it had limited flight capabilities, it probably nested on the ground.
Many other
endemic species
Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
of Réunion became extinct after the human colonisation and the resulting disruption of the island's
ecosystem
An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...
. The Réunion ibis lived alongside other recently extinct birds such as the
hoopoe starling, the
Mascarene parrot, the
Réunion parakeet
The echo parakeet (''Psittacula eques'') is a species of parrot endemic to the Mascarene Islands of Mauritius and formerly Réunion. It is the only living native parrot of the Mascarene Islands; all others have become extinct due to human activit ...
, the Réunion swamphen, the
Réunion scops owl, the
Réunion night heron, and the
Réunion pink pigeon. Extinct reptiles include the
Réunion giant tortoise and an undescribed ''
Leiolopisma'' skink. The
small Mauritian flying fox and the snail ''
Tropidophora carinata'' lived on Réunion and Mauritius, but vanished from both islands.
Extinction

As Réunion was populated by settlers, the Réunion ibis appears to have become confined to the tops of mountains. Introduced predators such as cats and rats took a toll. Overhunting also contributed and several contemporary accounts state the bird was widely hunted for food.
In 1625, John Tatton described the
tameness of the bird and how easy it was to hunt, as well as the large quantity consumed:
In 1671, Melet mentioned the culinary quality of this species, and described the slaughter of several types of birds on the island:
The last definite account of the "solitaire" of Réunion was Feuilley's from 1708, indicating that the species probably became extinct sometime early in the century.
In the 1820s, the French navigator
Louis de Freycinet asked an old slave about ''drontes'' (old Dutch word for dodo), and was told the bird existed around
Saint-Joseph when his father was an infant. This would perhaps be a century earlier, but the account may be unreliable. Cheke and Hume suspect that
feral cats initially hunted wildlife in the lowlands and later turned to higher inland areas, which were probably the last stronghold of the Réunion ibis, as they were unreachable by pigs. The species is thought to have been driven to extinction around 1710–1715.
References
External links
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{{DEFAULTSORT:Reunion Ibis
Birds described in 1848
Bird extinctions since 1500
Birds of Réunion
Controversial bird taxa
†
Extinct birds of Indian Ocean islands
Ibises
Threskiornis
Taxa named by Edmond de Sélys Longchamps