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Réunion Ibis
1854 restoration of the bird by Hermann Schlegel
Conservation status
Extinct (early 18th C.)  (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Pelecaniformes
Family:	Threskiornithidae
Genus:	Threskiornis
Species:	T. solitarius
Binomial name
Threskiornis solitarius (de Sélys-Longchamps, 1848)
Former range (encircled)
Synonyms
List Apterornis solitarius de Sélys-Longchamps, 1848 Raphus solitarius de Sélys-Longchamps, 1848 Didus apterornis Schlegel, 1854 Ornithaptera borbonica Bonaparte, 1854 Didus borbonicus Schlegel, 1873 Ornithaptera solitarius Hachisuka, 1953 Victoriornis imperialis Hachisuka, 1953 Borbonibis latipes Mourer & Moutou, 1987

The Réunion Ibis or Réunion Sacred Ibis (Threskiornis solitarius) is an extinct species of ibis that was endemic to the island of Réunion, east of Madagascar in the Indian Ocean. The first remains were found in 1974, and the ibis was first scientifically described in 1987. Its closest relatives are the African Sacred Ibis and the Straw-necked Ibis.

Travellers' accounts from the 17th and 18th centuries described a white bird on Réunion which flew with difficulty, which was subsequently referred to as the Réunion Solitaire. In the mid‐19th century, these accounts were incorrectly assumed to refer to white relatives of the Dodo, due to one account specifically mentioning Dodos, and because 17th century paintings of white Dodos had recently surfaced. Therefore, the Réunion Solitaire was long believed to be a member of the pigeon subfamily Raphinae. However, no fossils referable to this subfamily were ever found on Réunion, and it was later questioned whether the paintings had anything to do with the island. In the late 20th century, the discovery of a subfossil ibis led to the idea that these old accounts actually referred to that species instead. The idea that the solitaire and the subfossil ibis are identical has only met with limited dissent, and is now widely accepted.

Combined, the old accounts and incomplete 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, 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.

The diet of the Réunion Ibis was worms and other items foraged from soil. Subfossil wing-bones indicate it had reduced flight capabilities, a feature perhaps linked to seasonal fat-cycles. It preferred solitude (hence the name "solitaire") and it may have used its wings in combat. It lived in mountainous areas, but it may have been confined to these remote heights by heavy hunting by humans in more accessible areas, who arrived on the island in the 17th century, and predation by their introduced animals. These factors are believed to have driven the Réunion Ibis to extinction by the early 18th century.

Taxonomy

Early classification

The taxonomic history of the Réunion Ibis is convoluted, due to the ambiguous and meagre evidence that was available to scientists until recently. The supposed "white Dodo" of Réunion is now believed to have been an erroneous conjecture based on the few contemporary reports, combined with paintings of white Dodos by the Dutch painters Pieter Withoos and Pieter Holsteyn II (and derivatives) from the 1600s that surfaced in the 19th century.

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:

There were also Dod-eersen , 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.

When his journal was published in 1646, it was accompanied by an engraving copied after one of the Dodos in the Flemish painter Roelant Savery's "Crocker Art Gallery sketch". Since Bontekoe was shipwrecked and lost all his belongings after visiting Réunion in 1619, he may not had been able to write his account until seven years later when he returned to Holland. It is likely that he wrote it from memory, and it may therefore not be entirely reliable.

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 the bird as the "solitaire". The marooned Huguenot François Leguat used the name "solitaire" for the raphine bird he encountered on the nearby island of Rodrigues in the 1690s, but it is thought he borrowed the name from a tract which mentioned the Réunion species.

M. Carré of the French East Indies Company described the Réunion Solitaire in 1699, explaining the reason for its name:

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.

No specimens of the bird were ever preserved. The two solitaires Carré attempted to send to the royal menagerie in France did not survive in captivity. Billiard claimed that 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.

In the 1770s, the French naturalist Comte de Buffon stated that the Dodo inhabited both Mauritius and Réunion, but the basis for this claim is unknown. English naturalist Hugh Edwin Strickland discussed the old descriptions of the Réunion Solitaire in his 1848 book The Dodo and Its Kindred, and concluded it was distinct from the Dodo and Rodrigues Solitaire. Baron Edmund 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. In 1854, Hermann Schlegel 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 or stork-like bird instead of a Dodo. As the name Apterornis had already been used for a different bird by Richard Owen, 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 1856, William Coker announced the discovery of a 17th century "Persian" 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, including John Gould, Alfred Newton, and Walter Rothschild, subsequently assumed the image depicted the white solitaire of Réunion. Simultaneously, several similar paintings of white Dodos by Pieter Holsteyn II were discovered in the Netherlands. The images were thought to have been drawn after the same live bird, but they 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 other white Dodo pictures are thought to be based on these paintings. Dutch zoologist Anthonie Cornelis Oudemans suggested 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. Rothschild claimed the yellow wings might have been due to albinism in this particular specimen, and that the blunt beak seen in the Withoos painting was because the bird had its beak trimmed to prevent it from injuring humans. By the early 20th century, many other paintings and even physical remains were claimed to be white Dodos, amid much speculation. Some believed the solitaire of the old descriptions was rather a species similar to the Rodrigues Solitaire. Rothschild commissioned British artist Frederick William Frohawk to restore the Réunion Solitaire as a white Dodo, based on the Withoos painting and another based on Dubois' description, for his 1907 book Extinct Birds. In 1953, the Japanese writer Masauji Hachisuka went as far as referring to the white Dodos of the paintings as Victoriornis imperialis, and the solitaire of the accounts as Ornithaptera solitarius.

Recent classification

Until the late 1980s, only a few researchers doubted the connection between the solitaire accounts and the Dodo paintings. They cautioned 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, Robert W. Storer predicted that if any such remains were found, they would not belong to Raphinae, or even columbidae.

The first subfossil bird remains on Réunion were found in 1974, and assigned to a stork, Ciconia sp. In 1987, subfossils of a recently extinct species of ibis from Réunion were described as Borbonibis latipes, and thought related to the bald ibises of the genus Geronticus. In 1994, the "stork" remains were shown to belong to this ibis as well. The 1987 discovery led biologist Anthony S. Cheke to suggest to one of the describers, Francois Moutou, that the subfossils may have been of the Réunion Solitaire. This suggestion was published by the describers of Borbonibis in 1995, and they also reassigned it to the genus Threskiornis, now combined with the specific epithet solitarius from de Sélys-Longchamps' 1848 binomial for the solitaire. The authors pointed out that the contemporary descriptions matched the appearance and behaviour of an ibis more than a member of the Raphinae, especially since a fragment of a comparatively short and straight ibis mandible was discovered in 1994, 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. Morphological study suggests its closest relatives are the African Sacred Ibis (T. aethiopicus) of Africa and the Straw-necked Ibis (T. spinicollis) of Australia. The African Sacred Ibis also has similar coloured plumage to that described in the old descriptions of the Réunion Solitaire. It may be closest to that species, and therefore of African origin.

The possible basis for the 17th century white Dodo paintings has also recently been examined by biologist Arturo Valledor de Lozoya in 2003, and independently by experts of Mascarene fauna Anthony Cheke and Julian Hume in 2004. According to these authors, it appears that the pictures were derived from a previously unreported painting containing a whitish Dodo, called Landscape with Orpheus and the animals, produced by Roelant Savery circa 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 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.

Réunion island is only three million years old, whereas Mauritius and Rodrigues, with each their raphine species, are eight to ten million years old, and 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. No fossil remains of Dodo-like birds have ever been found on Réunion. A few later sources take issue with the proposed ibis-identity of the solitaire, and have even regarded the "white Dodo" as a valid species. British writer Errol Fuller agrees 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.

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. Sieur Dubois' 1674 account is the most detailed contemporary description of the bird, here as translated by Captain Pasfield Oliver in 1897:

Solitaires. These birds are thus named because they always go alone. They are as big as a big goose and have white plumage, black at the extremity of the wings and of the tail. At the tail there are some feathers resembling those of the Ostrich. They have the neck long and the beak formed like that of the Woodcocks, but larger, and the legs and feet like those of Turkey-chicks. This bird betakes itself to running, only flying but very little. It is one of the best game on the Island.

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.

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. 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 is elongated and the radius and ulna are robust, as in flighted birds, but a particular foramen between a metacarpal and the alular is otherwise only known from flightless birds, such as some ratites, penguins, and several extinct species. As contemporary accounts are inconsistent on whether the Solitaire was flightless or had some flight capability, Mourer-Chauvire suggested that this was dependent on seasonal fat-cycles, meaning that individuals were fat during cool seasons, but slim during hot seasons; perhaps it could not fly when it was fat, but could when it was slim.

Behaviour and ecology

The species was termed a land-bird by Dubois, so it did not live in typical ibis habitats such as wetlands. It has been proposed that this is because the ancestors of the bird colonised Réunion before swamps had developed, and had therefore became 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. It appears to have lived in high altitudes, and perhaps had a limited distribution. The only mention of its diet and exact habitat is Feuilley's account from 1708, which is also the last record of a living individual:

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.

The diet and mode of obtaining it described by Feuilley matches that of an ibis, whereas members of the Raphinae are known to have been frugivorous. 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 1600s 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 of Réunion became extinct after the arrival of man, heavily damaging the ecosystem of the island. 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 Owl, the Réunion Night Heron, and the Réunion Pink Pigeon. Extinct reptiles include the Réunion giant tortoise and the Mauritian giant 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:

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.

In 1671, Melet described the slaughter of several types of birds on the island, and mentioned the culinary quality of this species:

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 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 ... (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.

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, Louis Henri 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 around 1710–1715, 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

1. Template:IUCN
2. ^ "The white dodo of Réunion Island: unravelling a scientific and historical myth". Archives of Natural History. 31 (1): 57–79. 2004. {{cite journal}}: Unknown parameter |authors= ignored (help)
3. ^ Strickland, H. E.; Melville, A. G. (1848). 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. London: Reeve, Benham and Reeve. pp. 57–62.
4. ^ Cheke, A. S.; Hume, J. P. (2008). Lost Land of the Dodo: an Ecological History of Mauritius, Réunion & Rodrigues. New Haven and London. pp. 30–43. ISBN 978-0-7136-6544-4.{{cite book}}: CS1 maint: location missing publisher (link)
5. Bontekoe van Hoorn, W. (1646). Journael ofte Gedenk waerdige beschrijvinghe van de Oost-Indische Reyse van Willem Ysbrantz. Bontekoe van Hoorn (in Dutch). Amsterdam: Jooft Hartgers. p. 76.
6. ^ Hume, J. P.; Walters, M. (2012). Extinct Birds. London: A & C Black. pp. 67–68. ISBN 1-4081-5725-X.
7. Olson, S. (1977). Rails of the World – A Monograph of the Family Rallidae: A synopsis on the fossil Rallidae. Boston: Codline. pp. 357–358. ISBN 0-87474-804-6.
8. Schlegel, H. (1854). "Ook een Woordje over den Dodo (Didus ineptus) en zijne Verwanten". Verslagen en Mededeelingen der Koninklijke Akademie van Wetenschappen (in Dutch). 2: 232–256.
9. ^ Mourer-Chauvire, C.; Bour, R.; Ribes, S.; Moutou, F. (1999). "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". Smithsonian Contributions to Paleobiology: Proceedings of the 4th International Meeting of the Society of Avian Paleontology and Evolution, Washington, D.C, 4–7 June 1996. 89: 8–11. {{cite journal}}: line feed character in |journal= at position 58 (help); line feed character in |title= at position 35 (help)
10. Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.2307.2F4073093, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.2307.2F4073093 instead.
11. ^ Rothschild, W. (1907). Extinct Birds. London: Hutchinson & Co. pp. 175–176.
12. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1093/jhc/15.2.201, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1093/jhc/15.2.201 instead.
13. Greenway, J. C. (1967). Extinct and Vanishing Birds of the World. New York: American Committee for International Wild Life Protection 13. p. 111. ISBN 0-486-21869-4.
14. Mourer-Chauviré, C.; Moutou, F. (1987). "Découverte d'une forme récemment éteinte d'ibis endémique insulaire de l'île de la Réunion Borbonibis latipes n. gen. n. sp". Comptes rendus de l'Académie des sciences. Série D (in French). 305 (5): 419–423. {{cite journal}}: Unknown parameter |trans_title= ignored (|trans-title= suggested) (help)
15. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1038/373568a0, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1038/373568a0 instead.
16. ^ Fuller, E. (2002). Dodo – From Extinction To Icon. London: HarperCollins. pp. 168–172. ISBN 978-0-00-714572-0. {{cite book}}: Invalid |ref=harv (help)
17. Fuller, E. (2001). Extinct Birds (revised ed.). New York: Comstock. pp. 385–386. ISBN 978-0-8014-3954-4. {{cite book}}: Invalid |ref=harv (help)
18. Dubois, Sieur (1674). Les voyages faits par le sieur D. B. aux Isles Dauphine ou Madagascar, et Bourbon, ou Mascarenne, és années 1669, 70, 71 et 72. Dans laquelle il est curieusement traité du Cap Vert, de la ville de Surate, des isles de Sainte Helene, ou de l´Ascention. Ensemble les moeurs, religions, forces, gouvernemens et coutumes des habitans des dites isles, avec l´histoire naturelle du pais (in French). Paris: Chez Claude Barbin. p. 170.
19. Dubois, Sieur (translated and edited by Captain Oliver, Pasield Samuel) (1897). "The voyages made by the sieur D.B. to the islands Dauphine or Madagascar & Bourbon or Mascarenne in the years 1669. 70. 71 & 72". London: Printed for D. Nutt by T. and A. Constable. p. 77. {{cite web}}: |author= has generic name (help)CS1 maint: multiple names: authors list (link)

External links

• The Dodo – The merging of myth and reality: Half hour video interview with expert Julian Hume about the white Dodo

• IUCN Red List extinct species
• Animals described in 1848
• Bird extinctions since 1500
• Birds of Réunion
• Extinct birds of Indian Ocean islands
• Ibises
• Threskiornis
• Controversial bird taxa