View source for Réunion ibis

{{short description|Extinct bird that was endemic to Réunion}}
{{Use dmy dates|date=August 2020}}
{{featured article}}
{{speciesbox
| name = Réunion ibis
| status = EX
| status_system = IUCN3.1
| status_ref =<ref name="iucn status 12 November 2021">{{cite iucn |author=BirdLife International |date=2017 |title=''Threskiornis solitarius'' |volume=2017 |page=e.T22728791A119423949 |doi=10.2305/IUCN.UK.2017-3.RLTS.T22728791A119423949.en |access-date=12 November 2021}}</ref>
| extinct = early 18th century
| image = Réunion Ibis.jpg
| image_caption = Hypothetical [[paleoart|restoration]] based on contemporary descriptions, [[subfossil]] remains, and extant relatives
| genus = Threskiornis
| species = solitarius
| authority = ([[Edmond de Sélys Longchamps|de Sélys-Longchamps]], 1848)
| synonyms = {{collapsible list|bullets = true|title=<small>List</small>
|''Apterornis solitarius'' <small>Sélys, 1848</small>
|''Raphus solitarius'' <small>Sélys, 1848</small>
|''Didus apterornis'' <small>(Schlegel, 1854)</small>
|''Pezophaps borbonica'' <small>Bonaparte, 1854</small>
|''Ornithaptera borbonica'' <small>(Bonaparte, 1854)</small>
|''Apterornis solitaria'' <small>(Milne-Edwards, 1869)</small>
|''Didus borbonica'' <small>(Schlegel, 1873)</small>
|''Didus borbonicus'' <small>(Schlegel, 1875)</small>
|''Ornithaptera solitarius'' <small>(Hachisuka, 1953)</small>
|''Victoriornis imperialis'' <small>Hachisuka, 1937</small>
|''Borbonibis latipes'' <small>Mourer & Moutou, 1987</small>}}
|range_map= LocationReunion.svg
|range_map_caption=Location of [[Réunion]] (encircled)}}

The '''Réunion ibis''' or '''Réunion sacred ibis''' ('''''Threskiornis solitarius''''') is an [[list of extinct birds|extinct]] [[species]] of [[ibis]] that was [[endemic]] to the volcanic island of [[Réunion]] in the [[Indian Ocean]]. The first [[subfossil]] 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]], 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]]-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&nbsp;cm (25&nbsp;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 people|Dutch]] painters [[Pieter Withoos]] and [[Pieter Holsteyn II]] (and derivatives) from the 17th century that surfaced in the 19th century.<ref name="White Dodo"/>

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:<ref name="White Dodo"/>
{{Blockquote|I saw a kind of bird in this place which I have not found elsewhere; it is that which the inhabitants call the Oiseaux Solitaire for to be sure, it loves solitude and only frequents the most secluded places; one never sees two or more together; it is always alone. It is not unlike a turkey, if it did not have longer legs. The beauty of its plumage is a delight to see. It is of changeable colour which verges upon yellow. The flesh is exquisite; it forms one of the best dishes in this country, and might form a dainty at our tables. We wished to keep two of these birds to send to France and present them to His Majesty, but as soon as they were on board ship, they died of melancholy, having refused to eat or drink.<ref name="Strickland"/>}}

{{multiple image
|align = left
|total_width = 400
|image1 = DodoBontekoe.jpg
|alt1 = 
|caption1 = 1646 etching of a [[dodo]] that [[Willem Ysbrandtszoon Bontekoe]] claimed to have seen on Réunion
|image2 = Roelandt Savery - 'Dodo Birds', Chalk, black and amber on cream paper.jpg
|caption2 = [[Roelandt Savery]] sketch of three dodos from {{circa|lk=no|1626}}; the etching used by Bontekoe was derived from the dodo on the left
|alt2 = Sketch of three dodos, two in the foreground, one in the distance
}}

The [[marooning|marooned]] French [[Huguenot]] [[François Leguat]] used the name "solitaire" for the [[Rodrigues solitaire]], 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 (literature)|tract]] by Marquis Henri Duquesne which mentioned the Réunion species. Duquesne himself had probably based his own description on an earlier one.<ref name="White Dodo"/> No specimens of the "solitaire" were ever preserved.<ref name="Extinct Birds"/>

The two individuals Carré attempted to send to the [[Subsidiary structures of the Palace of Versailles|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.<ref name="Lost Land"/>

The only contemporary writer who referred specifically to "dodos" inhabiting [[Réunion]] was the Dutch sailor [[Willem Ysbrandtszoon Bontekoe]], though he did not mention their colouration:<ref name="White Dodo"/><ref>{{cite book |last=Bontekoe van Hoorn |first=W. |title=Journael ofte Gedenk waerdige beschrijvinghe van de Oost-Indische Reyse van Willem Ysbrantz. Bontekoe van Hoorn |publisher=Jooft Hartgers |location=Amsterdam |year=1646 |page=76 |language=nl }}</ref>
{{Blockquote|There were also ''Dod-eersen'' [old Dutch for dodos], which have small wings, and so far from being able to fly, they were so fat that they could scarcely walk, and when they tried to run, they dragged their under side along the ground.<ref name="Strickland"/>}}
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 people|Flemish]] painter [[Roelant Savery]]'s "Crocker Art Gallery sketch".<ref name="Lost Land">{{cite book |last1=Cheke |first1=A. S. |last2=Hume |first2=J. P. |year=2008 |url=https://books.google.com/books?id=OGeENV4exXcC |title=Lost Land of the Dodo: An Ecological History of Mauritius, Réunion & Rodrigues |location=New Haven and London |pages=30–43 |isbn=978-0-7136-6544-4}}</ref> Since Bontekoe was [[shipwreck]]ed and lost all his belongings after visiting Réunion in 1619, he may not have written his account until he returned to [[Holland]], seven years later, which would put its reliability in question.<ref name="White Dodo"/> He may have concluded in hindsight that it was a dodo, finding what he saw similar to accounts of that bird.<ref name="Avian extinctions">{{cite journal |last1=Mourer-Chauviré |first1=C. |first2=S. |last2=Bour |first3=R. |last3=Ribes |year=2006 |title=Recent avian extinctions on Réunion (Mascarene islands) from paleontological and historical sources |journal=Bulletin of the British Ornithologists' Club |issue=126 |pages=40–48}}</ref>

===Early interpretation===

{{multiple image
|align = right
|total_width = 400
|image1 = Reunion dodo.jpg
|alt1 = Painting of a white dodo among various birds
|caption1 = [[Pieter Withoos]]'s late 17th-century painting of a white dodo, the first of such paintings to be discovered
|image2 = White dodo.jpg
|caption2 = One of [[Pieter Holsteyn II]]'s mid-17th-century paintings of a white dodo
|alt2 = 
}}

In the 1770s, the French naturalist [[Comte de Buffon]] stated that the dodo inhabited both [[Mauritius]] 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.<ref name="White Dodo"/> The English naturalist [[Hugh Edwin Strickland]] 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.<ref name="Strickland">{{cite book |last1=Strickland |first1=H. E. |author-link=Hugh Edwin Strickland |last2=Melville |first2=A. G.| author2-link = Alexander Gordon Melville |title=The Dodo and Its Kindred; or the History, Affinities, and Osteology of the Dodo, Solitaire, and Other Extinct Birds of the Islands Mauritius, Rodriguez, and Bourbon |publisher=Reeve, Benham and Reeve |location=London |year=1848 |pages=[https://archive.org/details/dodoitskindredor00stri/page/57 57]–62 |url=https://archive.org/details/dodoitskindredor00stri}}</ref>

The Belgian scientist [[Edmond de Sélys Longchamps]] coined the [[scientific name]] ''Apterornis solitarius'' for the "solitaire" in 1848, apparently making it the [[type species]] of the genus, in which he also included two other [[Mascarene]] birds only known from contemporary accounts, the [[red rail]] and the [[Réunion swamphen]].<ref name="OlsonB">{{cite book |last=Olson |first=S. |title=Rails of the World&nbsp;– A Monograph of the Family Rallidae |publisher=Codline |chapter=A synopsis of the fossil Rallidae |location=Boston |year=1977 |pages=357–358 |hdl=10088/12826 |isbn=978-0-87474-804-8 }}</ref> As the name ''[[Apterornis]]'' had already been used for a different bird by the English biologist [[Richard Owen]], and the other former names were likewise invalid, Bonaparte coined the new [[binomial name|binomial]] ''Ornithaptera borbonica'' in 1854 ([[House of Bourbon|Bourbon]] was the original French name for Réunion).<ref name="Avifauna"/> In 1854, the German ornithologist [[Hermann Schlegel]] placed the "solitaire" in the same genus as the dodo, and named it ''Didus apterornis''.<ref>{{Cite journal |last=Schlegel |first=H. |title=Ook een Woordje over den Dodo (''Didus ineptus'') en zijne Verwanten |journal=Verslagen en Mededeelingen der Koninklijke Akademie van Wetenschappen |volume=2 |pages=232–256 |language=nl |url=https://archive.org/stream/verslagenenmeded02koni#page/232/mode/2up |year=1854}}</ref> He restored it strictly according to contemporary accounts, which resulted in an [[ibis]] or [[stork]]-like bird instead of a dodo.<ref name="White Dodo"/>

{{multiple image
|align = left
|total_width = 400
|image1 = Dodo reunion-Rothschild.jpg
|alt1 = 
|caption1 = [[Frederick William Frohawk]]'s 1907 restoration of the "solitaire", adapted from Withoos' white dodo
|image2 = Reunion Solitaire.png
|caption2 = Frohawk's alternate restoration, based on [[Sieur Dubois]]' description
|alt2 = 
}}

In 1856, William Coker announced the discovery of a 17th-century "[[Persia]]n" painting of a white dodo among [[waterfowl]], 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]]. Simultaneously, several similar paintings of white dodos by Pieter Holsteyn II were discovered in the Netherlands.<ref name="White Dodo"/> Other paintings and drawings were also later identified as showing white dodos.<ref name="Parish">{{cite book|last1=Parish|first1=Jolyon C.|title=The Dodo and the Solitaire: A Natural History|date=2013|publisher=Indiana University Press|location=Bloomington |isbn=978-0-253-00099-6 |pages=105–106, 141–164}}</ref> In 1869, the English ornithologist [[Alfred Newton]] 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.<ref>{{Cite journal |last1=Newton |first1=A. |title=XIII. On a picture supposed to represent the didine bird of the island of Bourbon (Réunion) |doi=10.1111/j.1096-3642.1868.tb00581.x |journal=The Transactions of the Zoological Society of London |volume=6 |issue=6 |pages=373–376 |year=1868 }}</ref>

Newton's words particularly cemented the validity of this connection among contemporary peers, and several of them expanded on his views.<ref name="White Dodo"/> 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]].<ref name="Oudemans">{{cite journal |last1=Oudemans |first1=A. C. |title=Dodo-studiën. Naar Aanleiding Van de Vondst Van Een Gevelsteen Met Dodo-Beeld Van 1561 Te Vere |journal=Verhandlingen der Koninklijke Akademie van Wetenschappen |date=1917 |volume=2 |issue=4 |pages=56–100 |doi=10.5962/bhl.title.15314 |url=https://www.biodiversitylibrary.org/item/52260#page/7/mode/1up |language=nl}}</ref> The British zoologist [[Walter Rothschild]] claimed in 1907 that the yellow wings might have been due to [[albinism]] in this particular specimen, since the old descriptions described these as black.<ref name="Rothschild">{{Cite book |last=Rothschild |first=W. |title=Extinct Birds |publisher=Hutchinson & Co |year=1907 |location=London |pages=171–176 |url=https://archive.org/stream/extinctbirdsatte00roth#page/174/mode/2up}}</ref> 

By the early 20th century, many other paintings and even physical remains were claimed to be of white dodos, amid much speculation.<ref name="White Dodo"/> 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 (Rothschild book)|Extinct Birds]]''.<ref name="Rothschild"/> 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]]), and the "solitaire" of the accounts as ''Ornithaptera solitarius'' (using the generic name coined by Bonaparte).<ref name="Hachisuka1937">{{cite journal |last1=Hachisuka |first1=M. |title=Revisional note on the didine birds of Réunion |journal=Proceedings of the Biological Society of Washington |date=1937 |volume=50 |pages=69–71 |url=https://www.biodiversitylibrary.org/page/34510406#page/99/mode/1up}}</ref><ref name="de Lozoya"/> 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]] or a [[bustard]].<ref name="Hachisuka1937"/><ref>{{cite journal |last1=Wood |first1=Casey A. |title=Two hitherto unpublished pictures of the Mauritius Dodo |journal=Ibis |date=1927 |volume=69 |issue=3 |pages=724–732 |doi=10.1111/j.1474-919X.1927.tb05377.x}}</ref><ref name="Parish"/>

===Modern interpretation===

[[File:NHM Dodos.jpg|thumb|alt=Stuffed whitish dodo|[[Rogue taxidermy]] of the supposed dodo of Réunion (right) and the dodo of [[Mauritius]] (left), by [[Rowland Ward]], [[Natural History Museum in London]]]]
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]] family like them).<ref name="White Dodo"/><ref name =Greenway>{{cite book |last=Greenway |first=J. C. |title=Extinct and Vanishing Birds of the World |publisher=American Committee for International Wild Life Protection 13 |location=New York |year=1967 |pages=110–111, 122–124 |isbn=978-0-486-21869-4 }}</ref><ref>{{cite journal |doi=10.2307/4083934 |last=Storer |first=R. W. |year=1970 |title=Independent Evolution of the Dodo and the Solitaire |journal=The Auk |volume=87 |issue=2 |url=http://sora.unm.edu/node/21993 |pages=369–370 |jstor=4083934}}</ref>

The first subfossil bird remains on Réunion, the lower part of a [[tarsometatarsus]], 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]].<ref name="Cowles87">{{Cite book |doi=10.1017/CBO9780511735769.004| editor1-last = Diamond| editor1-first = A. W. |title=Studies of Mascarene Island Birds |chapter=The fossil record |pages=90–100 |year=1987 |location=Cambridge |last1=Cowles |first1=G. S. |isbn=978-0-511-73576-9}}</ref> Also in 1987, a subfossil tarsometatarsus of an ibis found in a cave was described as ''Borbonibis latipes'' (the [[specific name (zoology)|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''.<ref name="Borbonibis">{{cite journal |last1=Mourer-Chauviré |first1=C. |first2=F. |last2=Moutou |year=1987 |title=Découverte d'une forme récemment éteinte d'ibis endémique insulaire de l'île de la Réunion ''Borbonibis latipes'' n. gen. n. sp |language=fr |journal=[[Comptes Rendus de l'Académie des Sciences]] |volume=305 |issue=5 |pages=419–423 |url= https://www.researchgate.net/publication/283945316}}</ref>

In 1994, Cowles concluded that the "stork" remains he had reported belonged to ''Borbonibis'', since their tarsometatarsi were similar.<ref name="Cowles1994">{{cite journal |last1=Cowles |first1=G. S. |title=A new genus, three new species and two new records of extinct Holocene birds from Réunion Island, Indian Ocean |journal=Geobios |date=1994 |volume=27 |issue=1 |pages=87–93 |doi=10.1016/S0016-6995(06)80215-9|bibcode=1994Geobi..27...87C }}</ref> 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".<ref name="White Dodo"/> 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".<ref name="Probst1995">{{cite journal |last1=Probst |first1=J.-M. |title=Découverte d'un bec appartenant au Solitaire de Bourbon? |journal=Bulletin Phaethon |date=1995 |volume=1 |pages=44–45 |url=https://www.researchgate.net/publication/321996754}}</ref> 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 ''{{lang|la|solitarius}}'' from de Sélys-Longchamps' 1848 binomial for the "solitaire" (making ''Borbonibis latipes'' a [[junior synonym]]). 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.<ref name="Ibis"/>

[[File:Landscape with Orpheus and the animals.png|left|thumb|alt=Painting of various animals and people in a forest, including a whitish dodo|[[Roelant Savery]] painting with a whitish dodo in the lower right, 1611]]
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]]; 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 [[Rudolf II, Holy Roman Emperor|Holy Roman Emperor Rudolf II]] to whom Savery was contracted at the time (1607–1611).<ref name="White Dodo"/>

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.<ref name="White Dodo">{{cite journal |doi=10.3366/anh.2004.31.1.57 |last1=Hume |first1=J. P. |author-link1=Julian Pender Hume |last2=Cheke |first2=A. S. |year=2004 |title=The white dodo of Réunion Island: Unravelling a scientific and historical myth |journal=Archives of Natural History |volume=31 |issue=1 |pages=57–79 |url=https://www.researchgate.net/publication/289502850 }}</ref> 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.<ref name="de Lozoya">{{cite journal |doi=10.1093/jhc/15.2.201 |last1=de Lozoya |first1=A. V. |year=2003 |title=An unnoticed painting of a white Dodo |journal=Journal of the History of Collections |volume=15 |issue=2 |pages=201–210 }}</ref> 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.<ref name="early depiction">{{cite journal |last1=Parish |first1=J. C. |last2=Cheke |first2=A. S. |s2cid=89661119 |title=A newly-discovered early depiction of the Dodo (Aves: Columbidae: ''Raphus cucullatus'') by Roelandt Savery, with a note on another previously unnoticed Savery Dodo |journal=Historical Biology |date=2019|volume=31|issue=10 |pages=1402–1411 |doi=10.1080/08912963.2018.1457658}}</ref>

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.<ref name="Avifauna"/> 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.<ref name="Lost Land"/> 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.<ref name="Fuller Dodo">{{cite book |last=Fuller |first=E. |author-link=Errol Fuller |year=2002 |title=Dodo&nbsp;– From Extinction to Icon |publisher=[[HarperCollins]] |location=London |pages=168–172 |isbn=978-0-00-714572-0 }}</ref><ref name="Fuller Extinct">{{cite book |last=Fuller |first=E. |author-link=Errol Fuller |year=2001 |title=Extinct Birds |edition=revised |publisher=Comstock |location=New York |pages=385–386 |isbn=978-0-8014-3954-4 }}</ref> Cheke and Hume have dismissed such sentiments as being mere "belief" and "hope" in the existence of a dodo on the island.<ref name="White Dodo"/>

===Evolution===

{{multiple image
|align = right
|total_width = 450

|image1 = African Sacred ibis.jpg
|alt1 = Black and white bird

|image2 = Threskiornis spinicollis - Centenary Lakes.jpg
|alt2 = Black and white bird in wetland

|image3 = Ibis sacré de Madagascar.JPG
|alt3 = Black and white bird in a three

|footer = The [[African sacred ibis]], [[straw-necked ibis]], and [[Malagasy sacred ibis]], three extant relatives in the genus ''[[Threskiornis]]'', with similarities in plumage
}}

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.<ref name="White Dodo"/> 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]] [[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.<ref name="Avifauna"/>

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.<ref name="Ibis">{{cite journal |doi=10.1038/373568a0 |last1=Mourer-Chauviré |first1=C. C. |last2=Bour |first2=R. |last3=Ribes |first3=S. |s2cid=4304082 |year=1995 |title=Was the solitaire of Réunion an ibis? |journal=Nature |volume=373 |issue=6515 |pages=568 |ref={{sfnRef|Mourer-Chauviré et al.|1995}}
| bibcode = 1995Natur.373..568M|doi-access=free }}</ref> Cheke and Hume instead suggested that it was closest to the [[Malagasy sacred ibis]] (''T. bernieri''), and therefore of ultimately African origin.<ref name="Lost Land"/>

==Description==
[[File:Réunion Solitaire.jpg|thumb|[[Hermann Schlegel]]'s 1854 [[ibis]] or [[stork]]-like restoration, based on Dubois' description instead of as a dodo]]
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.<ref name="Fuller Dodo"/> Dubois' 1674 account is the most detailed contemporary description of the bird,<ref name="Rothschild"/> here as translated by Strickland in 1848:
{{Blockquote|''Solitaires''. These birds are so called because they always go alone. They are the size of a large Goose, and are white, with the tips of the wings and tail black. The tail feathers resemble those of an Ostrich; the neck is long, and the beak is like that of a Woodcock, but larger; the legs and feet like those of Turkeys. This bird has recourse to running, as it flies but very little.<ref name="Strickland"/>}}

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]] comparison.<ref name="Ibis"/> Cheke and Hume have suggested that the French word (''bécasse'') from Dubois' original description, usually translated to "woodcock", could also mean [[oystercatcher]], 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.<ref name="White Dodo"/> The bright colouration of the plumage mentioned by some authors may refer to [[iridescence]], as seen in the straw-necked ibis.<ref name="Avian extinctions"/>

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&nbsp;cm (25&nbsp;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 [[Chest|pectoral]] elements, only one feature indicates reduction in flight capability. The [[coracoid]] is elongated and the [[radius]] and [[ulna]] are robust, as in flighted birds, but a particular [[foramen]] (or opening) between a [[metacarpal]] and the [[alular]] is otherwise only known from flightless birds, such as some [[ratites]], [[penguins]], and several extinct species.<ref name="Avifauna">{{Cite journal |last1=Mourer-Chauvire |first1=C. |last2=Bour |first2=R. |last3=Ribes |first3=S. |last4=Moutou |first4=F. |title=Avian paleontology at the close of the 20th century: The avifauna of Réunion Island (Mascarene Islands) at the time of the arrival of the first Europeans |journal=Smithsonian Contributions to Paleobiology |volume=89 |pages=8–11 |year=1999 |hdl=10088/2005}}</ref><ref name="Extinct Birds"/>

==Behaviour and ecology==
[[File:African_Sacred_Ibis_(Threskiornis_aethiopicus)_foraging.jpg|thumb|left|The Réunion ibis is said to have fed from soil, like this African sacred ibis]]
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.<ref name="Ibis"/> However, Dubois specifically stated the "solitaires" did not have fat-cycles, unlike most other Réunion birds.<ref name="White Dodo"/> 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:
{{Blockquote|The solitaires are the size of an average turkey cock, grey and white in colour. They inhabit the tops of mountains. Their food is only worms and filth, taken on or in the soil.<ref name="Lost Land"/>}}
The diet and mode of [[foraging]] described by Feuilley matches that of an ibis, whereas members of the Raphinae are known to have been [[frugivorous|fruit eaters]].<ref name="Ibis"/> The species was termed a land-bird by Dubois, so it did not live in typical ibis habitats such as [[wetlands]]. 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.<ref name="Lost Land"/><ref name="Hume2019">{{cite journal |last1=Hume |first1=J. P. |title=Systematics, morphology and ecology of rails (Aves: Rallidae) of the Mascarene Islands, with one new species |journal=Zootaxa |date=2019 |volume=4626 |issue=1 |pages=49–51, 63–67 |doi=10.11646/zootaxa.4626.1.1 |pmid=31712544|s2cid=198258434 }}</ref>

The Réunion ibis appears to have lived in high altitudes, and perhaps had a limited distribution.<ref name="Extinct Birds">{{cite book |last1=Hume |first1=J. P. |first2=M. |last2=Walters |year=2012 |title=Extinct Birds |publisher=A & C Black |location=London |pages=67–68, 114 |isbn=978-1-4081-5725-1 |url=https://books.google.com/books?id=xpUBocGB12YC&q=Extinct+Birds+hume}}</ref> 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.<ref name="Lost Land"/>

Many other [[endemic species]] of Réunion became extinct after the human colonisation and the resulting disruption of the island's [[ecosystem]]. The Réunion ibis lived alongside other recently extinct birds such as the [[hoopoe starling]], the [[Mascarene parrot]], the [[Réunion parakeet]], 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.<ref name="Lost Land"/>

==Extinction==
[[File:Panorama-Cilaos-Greatoutdoors.jpg|thumb|Mountains on Réunion; this bird may have become confined to higher areas after the arrival of humans and their introduced animals.]]
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.<ref name="Extinct Birds"/> In 1625, John Tatton described the [[island tameness|tameness]] of the bird and how easy it was to hunt, as well as the large quantity consumed:
{{Blockquote|There is store of land fowle both small and great, plenty of Doves, great Parrats, and such like; and a great fowle of the bignesse of a Turkie, very fat, and so short winged, that they cannot fly, being white, and in a manner tame: and so be all other fowles, as having not been troubled nor feared with shot. Our men did beat them down with sticks and stones. Ten men may take fowle enough to serve fortie men a day.<ref name="Rothschild"/>}}
In 1671, Melet mentioned the culinary quality of this species, and described the slaughter of several types of birds on the island:
{{Blockquote|(A)nother sort of bird called solitaires which are very good (to eat) and the beauty of their plumage is most fascinating for the diversity of bright colours that shine on their wing and around their necks... There are birds in such great confusion and so tame that it is not necessary to go hunting with firearms, they can so easily be killed with a little stick or rod. During the five or six days that we were allowed to go into the woods, so many were killed that our General [de La Haye] was constrained to forbid anyone going beyond a hundred paces from the camp for fear the whole quarter would be destroyed, for one needed only to catch one bird alive and make it cry out, to have in a moment whole flocks coming to perch on people, so that often without moving from one spot one could kill hundreds. But, seeing that it would have been impossible to wipe out such a huge quantity, permission was again given to kill, which gave great joy to everyone, because very good fare was had at no expense.<ref name="Extinct Birds"/>}}
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.<ref name="Extinct Birds"/> 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, Réunion|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.<ref name="Lost Land"/>

==References==
{{Reflist|30em}}

==External links==
* {{Commons category-inline|Threskiornis solitarius|''Threskiornis solitarius''}}
* {{Wikispecies-inline|Threskiornis solitarius|''Threskiornis solitarius''}}

{{Threskiornithidae|state=collapsed}}
{{Birds}}
{{Portal bar|Birds|Animals|Biology|Africa|Madagascar|Paleontology}}
{{Taxonbar|from=Q18972}}

{{DEFAULTSORT:Reunion Ibis}}
[[Category:Birds described in 1848]]
[[Category:Bird extinctions since 1500]]
[[Category:Birds of Réunion]]
[[Category:Controversial bird taxa]]
[[Category:Extinct birds of Indian Ocean islands]]
[[Category:Ibises]]
[[Category:Threskiornis]]
[[Category:Taxa named by Edmond de Sélys Longchamps]]