The Réunion swamphen (''Porphyrio caerulescens''), also known as the Réunion gallinule or ' (French for "blue bird"), is a
hypothetical extinct species
Several species have been assumed to exist, but due to a lack of evidence they can only be regarded as potential species. They have caused confusion, as they may have been a separate species, a subspecies, an introduced species or a misidentifi ...
of
rail
Rail or rails may refer to:
Rail transport
*Rail transport and related matters
* Rail (rail transport) or railway lines, the running surface of a railway
Arts and media Film
* ''Rails'' (film), a 1929 Italian film by Mario Camerini
* ''Rail'' ...
that was endemic to the
Mascarene island
The Mascarene Islands (, ) or Mascarenes or Mascarenhas Archipelago is a group of islands in the Indian Ocean east of Madagascar consisting of the islands belonging to the Republic of Mauritius as well as the French department of Réunion. Thei ...
of
Réunion
Réunion (; french: La Réunion, ; previously ''Île Bourbon''; rcf, label= Reunionese Creole, La Rényon) is an island in the Indian Ocean that is an overseas department and region of France. It is located approximately east of the island ...
. While only known from 17th- and 18th-century accounts by visitors to the island, it was
scientifically named
In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
in 1848, based on the 1674 account by
Sieur Dubois
Sieur Dubois () or Sieur D. B. was a French traveller who reached the islands of Madagascar and Réunion at the time of early colonization by France. He wrote a book in French, published in 1674, about his journeys and the wildlife he saw including ...
. A considerable literature was subsequently devoted to its possible affinities, with current researchers agreeing it was derived from the
swamphen
''Porphyrio'' is the swamphen or swamp hen bird genus in the rail family. It includes some smaller species which are usually called "purple gallinules", and which are sometimes separated as genus ''Porphyrula'' or united with the gallinules pro ...
genus ''Porphyrio''. It has been considered mysterious and enigmatic due to the lack of any physical evidence of its existence.
This bird was described as entirely blue in plumage with a red beak and legs. It was said to be the size of a
Réunion ibis
The Réunion ibis or Réunion sacred ibis (''Threskiornis solitarius'') is an 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 fir ...
or chicken, which could mean in length, and it may have been similar to the
takahe. While easily hunted, it was a fast runner and able to fly, though it did so reluctantly. It may have fed on plant matter and invertebrates, as do other swamphens, and was said to nest among grasses and aquatic ferns. It was only found on the
Plaine des Cafres
The Plaine des Cafres is a plateau on Réunion Island, one of the French volcanic islands in the Mascarene Archipelago in the southwestern Indian Ocean. It is part of the commune of Le Tampon.
It is named after the Cafres, black slaves who hi ...
plateau, to which it may have retreated during the latter part of its existence, whereas other swamphens inhabit lowland swamps. While the last unequivocal account is from 1730, it may have survived until 1763, but overhunting and the introduction of cats likely drove it to
extinction
Extinction is the termination of a kind of organism or of a group of kinds ( taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed ...
.
Taxonomy
Visitors to the
Mascarene island
The Mascarene Islands (, ) or Mascarenes or Mascarenhas Archipelago is a group of islands in the Indian Ocean east of Madagascar consisting of the islands belonging to the Republic of Mauritius as well as the French department of Réunion. Thei ...
of
Réunion
Réunion (; french: La Réunion, ; previously ''Île Bourbon''; rcf, label= Reunionese Creole, La Rényon) is an island in the Indian Ocean that is an overseas department and region of France. It is located approximately east of the island ...
during the 17th and 18th centuries reported blue birds (' in French). The first such account is that of the French traveller
Sieur Dubois
Sieur Dubois () or Sieur D. B. was a French traveller who reached the islands of Madagascar and Réunion at the time of early colonization by France. He wrote a book in French, published in 1674, about his journeys and the wildlife he saw including ...
, who was on Réunion from 1669 to 1672, which was published in 1674.
The British naturalist
Hugh Edwin Strickland
Hugh Edwin Strickland (2 March 1811 – 14 September 1853) was an English geologist, ornithologist, naturalist and systematist. Through the British Association, he proposed a series of rules for the nomenclature of organisms in zoology, known a ...
stated in 1848 that he would have thought Dubois' account referred to a member of the
swamphen
''Porphyrio'' is the swamphen or swamp hen bird genus in the rail family. It includes some smaller species which are usually called "purple gallinules", and which are sometimes separated as genus ''Porphyrula'' or united with the gallinules pro ...
genus ''Porphyrio'' if not for its large size and other features (and noted the term ' had also been erroneously used for bats on Réunion in an old account). Strickland expressed hope that remains of this and other
extinct Mascarene birds would be found there.
Responding to Strickland's book later that year, the Belgian scientist
Edmond de Sélys Longchamps
Baron Michel Edmond de Selys Longchamps (25 May 1813 – 11 December 1900) was a Belgian Liberal Party politician and scientist. Selys Longchamps has been regarded as the founding figure of odonatology, the study of the dragonflies and dams ...
coined the
scientific name ''Apterornis coerulescens'' based on Dubois' account. The
specific name is
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...
for "bluish, becoming blue". Sélys Longchamps also included two other Mascarene birds, at the time only known from contemporary accounts, in the genus ''Apterornis'': the
Réunion ibis
The Réunion ibis or Réunion sacred ibis (''Threskiornis solitarius'') is an 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 fir ...
(now ''Threskiornis solitarius''); and the
red rail
The red rail (''Aphanapteryx bonasia'') is an extinct species of flightless rail. It was endemic to the Mascarene island of Mauritius, east of Madagascar in the Indian Ocean. It had a close relative on Rodrigues island, the likewise exti ...
(now ''Aphanapteryx bonasia''). He thought them related to the
dodo
The dodo (''Raphus cucullatus'') is an extinct flightless bird that was endemic to the island of Mauritius, which is east of Madagascar in the Indian Ocean. The dodo's closest genetic relative was the also-extinct Rodrigues solitaire. The ...
and
Rodrigues solitaire
The Rodrigues solitaire (''Pezophaps solitaria'') is an extinct flightless bird that was endemic to the island of Rodrigues, east of Madagascar in the Indian Ocean. Genetically within the family of pigeons and doves, it was most closely relate ...
, due to their shared rudimentary wings, tail, and the disposition of their digits.
The name ''Apterornis'' had already been used for a different extinct bird genus from
New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 List of islands of New Zealand, smaller islands. It is the ...
(originally spelled ''
Aptornis'', the adzebills) by the British biologist
Richard Owen
Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomist and paleontologist. Owen is generally considered to have been an outstanding naturalist with a remarkable gift for interpreting fossils.
Ow ...
earlier in 1848, and the French biologist
Charles Lucien Bonaparte
Charles Lucien Jules Laurent Bonaparte, 2nd Prince of Canino and Musignano (24 May 1803 – 29 July 1857), was a French naturalist and ornithologist. Lucien and his wife had twelve children, including Cardinal Lucien Bonaparte.
Life and career
...
coined the new
binomial
Binomial may refer to:
In mathematics
*Binomial (polynomial), a polynomial with two terms
*Binomial coefficient, numbers appearing in the expansions of powers of binomials
* Binomial QMF, a perfect-reconstruction orthogonal wavelet decomposition
...
''Cyanornis erythrorhynchus'' for the ' in 1857. The same year, 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 stimula ...
moved the species to the genus ''Porphyrio'', as ''P.'' (''Notornis'') ''caerulescens'', indicating an affinity with the
takahe (now called ''Porphyrio hochstetteri'', then also referred to as ''Notornis'' by some authors) of New Zealand. Schlegel argued that the discovery of the takahe showed that members of ''Porphyrio'' could be large, thereby disproving Strickland's earlier doubts based on size.
The British ornithologist
Richard Bowdler Sharpe
Richard Bowdler Sharpe (22 November 1847 – 25 December 1909) was an English zoologist and ornithologist who worked as curator of the bird collection at the British Museum of natural history. In the course of his career he published several mo ...
simply used the name ''Porphyrio caerulescens'' in 1894.
The British zoologist
Walter Rothschild
Lionel Walter Rothschild, 2nd Baron Rothschild, Baron de Rothschild, (8 February 1868 – 27 August 1937) was a British banker, politician, zoologist and soldier, who was a member of the Rothschild family. As a Zionist leader, he was present ...
retained the name ''Apterornis'' for the bird in 1907, and considered it similar to ''Aptornis'' and the takahe, believing Dubois's account indicated it was related to those birds.
The Japanese ornithologist
Masauji Hachisuka
, 18th Marquess Hachisuka, was a Japanese ornithologist and aviculturist.Delacour, J. (1953) The Dodo and Kindred Birds by Masauji Hachisuka (Review). The Condor 55 (4): 223.Peterson, A. P. (2013Author Index: Hachisuka, Masauji (Masa Uji), marqui ...
used the
new combination
''Combinatio nova'', abbreviated ''comb. nov.'' (sometimes ''n. comb.''), is Latin for "new combination". It is used in taxonomic biology literature when a new name is introduced based on a pre-existing name. The term should not to be confused wi ...
''Cyanornis coerulescens'' for the bird in 1953 (with the specific name
misspelled
Spelling is a set of conventions that regulate the way of using graphemes (writing system) to represent a language in its written form. In other words, spelling is the rendering of speech sound (phoneme) into writing (grapheme). Spelling is one ...
), also considering it related to the takahe due to its size.
Throughout the 20th century the bird was usually considered a member of ''Porphyrio'' or ''Notornis'', and the latter genus was eventually itself considered a junior
synonym
A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are al ...
of ''Porphyrio''.
Some writers equated the bird with extant swamphens, including
African swamphens by the French ornithologist
Jacques Berlioz
Jacques Berlioz (9 December 1891, Paris – 21 December 1975) was a French zoologist and ornithologist, specializing in hummingbirds. He was a grand-nephew of composer Hector Berlioz (1803–1869).
Berlioz was born in Paris, where the family h ...
in 1946, and
western swamphens by the French ornithologist Nicolas Barré in 1996, despite their different habitat. The French ornithologist Philippe Milon doubted the ''Porphyrio'' affiliation in 1951, since Dubois's account stated the Réunion bird was palatable, while extant swamphens are not.
In 1967, the American ornithologist
James Greenway
James Cowan Greenway (April 7, 1903 – June 10, 1989) was an American ornithologist. An eccentric, shy, and often reclusive man, his survey of extinct and vanishing birds provided the base for much subsequent work on bird conservation.
Early y ...
stated that the bird "must remain mysterious" until ''Porphyrio'' bones are one day uncovered.
In 1974, an attempt was made to find fossil localities on the
Plaine des Cafres
The Plaine des Cafres is a plateau on Réunion Island, one of the French volcanic islands in the Mascarene Archipelago in the southwestern Indian Ocean. It is part of the commune of Le Tampon.
It is named after the Cafres, black slaves who hi ...
plateau, where the bird was said to have lived. No caves, which might contain
kitchen middens
A midden (also kitchen midden or shell heap) is an old dump for domestic waste which may consist of animal bone, human excrement, botanical material, mollusc shells, potsherds, lithics (especially debitage), and other artifacts and ecofa ...
where early settlers discarded bones of local birds, were found, and it was determined that a more careful study of the area was needed before excavations could be made.
In 1977, the American ornithologist
Storrs L. Olson
Storrs Lovejoy Olson (April 3, 1944 – January 20, 2021) was an American biologist and ornithologist who spent his career at the Smithsonian Institution, retiring in 2008. One of the world's foremost avian paleontologists, he was best known ...
found the old accounts consistent with an
endemic
Endemism is the state of a species being found 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 found els ...
derivative of ''Porphyrio'', and considered it a probable species whose remains might one day be discovered.
The British ecologist
Anthony S. Cheke considered previous arguments about the bird's affinities in 1987, and supported it being a ''Porphyrio'' relative, while noting that there were two further contemporary accounts.
The same year, the British writer
Errol Fuller
Errol Fuller (born 19 June 1947) is an English writer and artist who lives in Tunbridge Wells, Kent. He was born in Blackpool, Lancashire, grew up in South London, and was educated at Addey and Stanhope School. He is the author of a series of bo ...
listed the bird as a
hypothetical species
Several species have been assumed to exist, but due to a lack of evidence they can only be regarded as potential species. They have caused confusion, as they may have been a separate species, a subspecies, an introduced species or a misidentifica ...
, and expressed puzzlement as to how a considerable literature had been derived from such "flimsy material".
The French palaeontologist Cécile Mourer-Chauviré and colleagues listed the bird as ''Cyanornis'' (?=''Porphyrio'') ''caerulescens'' in 2006, indicating the uncertainty of its classification. They stated the cause of the scarcity of its fossil remains was probably that it did not live in the parts of Réunion where fossils might have been preserved.
Cheke and the British palaeontologist
Julian P. Hume
Julian Pender Hume (born 3 March 1960) is an English palaeontologist, artist and writer who lives in Wickham, Hampshire. He was born in Ashford, Kent, and grew up in Portsmouth, England. He attended Crookhorn Comprehensive School between 1971 an ...
stated in 2008 that, since the mystery of the "Réunion solitaire" had been solved after it was identified with ibis remains, the Réunion swamphen remains the most enigmatic of the Mascarene birds from the old accounts.
In his 2012 book about extinct birds and his 2019
monograph about extinct Mascarene
rails
Rail or rails may refer to:
Rail transport
*Rail transport and related matters
* Rail (rail transport) or railway lines, the running surface of a railway
Arts and media Film
* ''Rails'' (film), a 1929 Italian film by Mario Camerini
* ''Rail'' ...
, Hume stated that the Réunion swamphen had been mentioned by trustworthy observers, but was "perhaps the most enigmatic of all rails" with no evidence to resolve its taxonomy. He thought there was no doubt that it was a derivative of ''Porphyrio'', as the all-blue colouration is only found in that genus among rails. While it may have been derived from Africa or Madagascar, genetic studies have shown that other rails have dispersed to unexpectedly great distances from their closest relatives, making alternative explanations possible.
Description

The Réunion swamphen was described as having entirely blue plumage with a red beak and legs, and is generally agreed to have been a large,
terrestrial
Terrestrial refers to things related to land or the planet Earth.
Terrestrial may also refer to:
* Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...
swamphen, with features indicative of reduced flight capability, such as larger size and more robust legs. There has been disagreement over the size of the bird, as Dubois' account compared its size with that of a Réunion ibis while that of the French engineer
Jean Feuilley from 1704 compared it to a
domestic chicken
The chicken (''Gallus gallus domesticus'') is a domesticated junglefowl species, with attributes of wild species such as the grey and the Ceylon junglefowl that are originally from Southeastern Asia. Rooster or cock is a term for an adult m ...
. Cheke stated in 1987 that Feuilley's account would indicate the bird was not unusually large, perhaps the size of a swamphen. Hume pointed out in 2019 that the Réunion ibis would have been at most, similar to the extant
African sacred ibis
The African sacred ibis (''Threskiornis aethiopicus'') is a species of ibis, a wading bird of the family Threskiornithidae. It is native to much of Africa, as well as small parts of Iraq, Iran and Kuwait. It is especially known for its role in ...
(including the tail), while chickens could be in length (the size of their ancestor, the wild
red junglefowl
The red junglefowl (''Gallus gallus'') is a tropical bird in the family Phasianidae. It ranges across much of Southeast Asia and parts of South Asia. It was formerly known as the Bankiva or Bankiva Fowl. It is the species that gave rise to the ...
), and there was therefore no contradiction. The Réunion swamphen would thereby have been about the same size as the takahe.
The first description of the Réunion swamphen is that of Dubois from 1674:
The last definite account of the bird is that of the priest Father Brown from around 1730 (expanded from a 1717 account by Le Gentil):
Olson stated the comparison to a "wood pigeon" was a reference to the
common wood pigeon
The common wood pigeon or common woodpigeon (''Columba palumbus''), also known as simply wood pigeon, wood-pigeon or woodpigeon, is a large species in the dove and pigeon family (Columbidae), native to the western Palearctic. It belongs to the g ...
, implying that Brown described it as smaller than Dubois did, while Hume suggested it could be the extinct
Réunion blue pigeon.
The 1708 account of Hébert does not add much information, though he qualified its colouration as "dark blue".
While the bird is only known from written accounts, reconstructions of it appear in Rothschild's 1907 book ''
Extinct Birds'', and Hachisuka's 1953 book ''The Dodo and Kindred Birds''.
Rothschild stated he had the Dutch artist
John Gerrard Keulemans
Johannes Gerardus Keulemans (J. G. Keulemans) (8 June 1842 – 29 March 1912) was a Dutch bird illustrator. For most of his life he lived and worked in England, illustrating many of the best-known ornithology books of the nineteenth century.
Bi ...
depict it as intermediate between the takahe and ''Aptornis'', which he thought its closest relatives.
Fuller found Frohawk's illustration to be a well-produced work, though almost entirely conjectural in depicting it like a slimmed-down takahe.
Behaviour and ecology

Little is known about the ecology of the Réunion swamphen; it was easily caught and killed, unlike other swamphens (which avoid predators by flying or hiding), though it was able to run fast.
While some early researchers thought the bird to be flightless, Brown's account states it could fly, and it is thought to have been a reluctant flier.
Hume suggested it may have fed on plant matter and invertebrates, as other swamphens do. At least in the latter part of its existence, it appears to have been confined to mountains (retreating there between the 1670s and 1705), in particular to the Plaine des Cafres plateau, situated at an altitude of about in south-central Réunion. The environment of this area consists of open woodland in a subalpine forest steppe, and has marshy pools.
The Réunion swamphen was termed a land-bird by Dubois, while other swamphens inhabit lowland swamps. This is similar to the Réunion ibis, which lived in forest rather than wetlands, which is otherwise typical ibis 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
ecological niche
In ecology, a niche is the match of a species to a specific environmental condition.
Three variants of ecological niche are described by
It describes how an organism or population responds to the distribution of resources and competitors (fo ...
.
Feuilley described some characteristics of the bird in 1704:
The only account of its nesting behaviour is that of La Roque from 1708:
Many other endemic species on Réunion became extinct after the arrival of humans and the resulting disruption of the island's
ecosystem
An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...
. The Réunion swamphen lived alongside other now-extinct birds, such as the Réunion ibis, the
Mascarene parrot
The Mascarene parrot or mascarin (''Mascarinus mascarinus'') is an extinct species of parrot that was endemic to the Mascarene island of Réunion in the western Indian Ocean. The taxonomic relationships of this species have been subject to de ...
, the
Hoopoe starling, 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 scops owl, the
Réunion night heron
The Réunion night heron (''Nycticorax duboisi'') is an extinct species of heron formerly occurring on the Mascarene island of Réunion.
It was for a long time only known from a single description, that of Dubois published in 1674. He stated:
...
, and the
Réunion pink pigeon. Extinct Réunion reptiles include the
Réunion giant tortoise and an undescribed ''
Leiolopisma
''Leiolopisma'' is a genus of skinks. Most species occur in the region of New Caledonia- New Zealand, and they are related to other genera from that general area, such as '' Emoia''; these and others form the '' Eugongylus'' group. One living ...
''
skink
Skinks are lizards belonging to the family Scincidae, a family in the infraorder Scincomorpha. With more than 1,500 described species across 100 different taxonomic genera, the family Scincidae is one of the most diverse families of lizards. S ...
. The
small Mauritian flying fox
The small Mauritian flying fox or dark flying fox (''Pteropus subniger''), known as a ''rougette'' to early French travelers, is an extinct species of megabat. It lived on the islands of Réunion and Mauritius in the Mascarene Islands of the Ind ...
and the snail ''
Tropidophora carinata'' lived on Réunion and Mauritius before vanishing from both islands.
Extinction
Many terrestrial rails are flightless, and island populations are particularly vulnerable to man-made changes; as a result, rails have suffered more extinctions than any other family of birds. All six endemic species of Mascarene rails are extinct, all caused by human activities.
Overhunting was the main cause of the Réunion swamphen's extinction (it was considered good
game
A game is a structured form of play, usually undertaken for entertainment or fun, and sometimes used as an educational tool. Many games are also considered to be work (such as professional players of spectator sports or games) or art (su ...
and was easy to catch), but according to Cheke and Hume, the introduction of cats at the end of the 17th century could have contributed to the elimination of the bird once these
became feral and reached its habitat. Today, cats are still a serious threat to native birds, in particular
Barau's petrel, since they occur all over Réunion, including the most remote and high peaks.
The eggs and chicks would also have been vulnerable to rats after their accidental introduction in 1676.
On the other hand, the Réunion swamphen and other birds of the island appear to have successfully survived
feral pigs.
Cattle grazing on Plaine des Cafres was promoted by the French explorer
Jean-Baptiste Charles Bouvet de Lozier
Jean-Baptiste Charles Bouvet de Lozier (14 January 1705 – 1786) was a French sailor, explorer, and governor of the Mascarene Islands.
He was orphaned at the age of seven and after being educated in Paris, he was sent to Saint Malo to study na ...
in the 1750s, which may have also had an impact on the bird.
While the last unequivocal account of the Réunion swamphen is from 1730, an anonymous account from 1763, possibly by the British Brigadier-General
Richard Smith Richard Smith may refer to:
Arts and entertainment
* Richard Penn Smith (1799–1854), American playwright
* Richard Smith (silent film director) (1886–1937), American silent film director
* Richard Smith (screenwriter), Scottish screenwriter, ...
, may be the last mention of this bird, though no description of it was provided, and it might refer to another species.
It is also impossible to say whether this writer saw the bird himself.
It gives a contemporary impression of the Réunion swamphen's habitat, Plaine des Cafres, and of how birds were hunted there:

If the Réunion swamphen survived until 1763 this would be far longer than many other extinct birds of Réunion. If so, its survival was likely because of the remoteness of its habitat.
See also
*
List of extinct animals of Réunion
This is a list of Madagascar and Indian Ocean Island animals extinct in the Holocene that covers extinctions from the Holocene epoch, a geologic epoch that began about 11,650 years before present (about 9700 BCE) and continues to the present da ...
References
{{DEFAULTSORT:Reunion Swamphen
Extinct birds of Indian Ocean islands
Porphyrio
Bird extinctions since 1500
Birds of Réunion
Birds described in 1848
Hypothetical extinct species