Rodrigues rail

Rodrigues rail
An illustration of bird bones, mostly laid out in vertical rows
Subfossil bones described in 1879; note that one skull has a straight beak, while that of the other is curved

Extinct  (mid-18th century) (IUCN 3.1)[1]
Scientific classification
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Erythromachus
Species:
E. leguati
Binomial name
Erythromachus leguati
A map showing the location of Rodrigues, an island east of Madagascar in the Indian Ocean
Location of Rodrigues
Synonyms

The Rodrigues rail or Leguat's gelinote (Erythromachus leguati) is an extinct, flightless rail that was endemic to the Mascarene island of Rodrigues, east of Madagascar in the Indian Ocean. It is sometimes assigned to the genus Aphanapteryx, along with its close relative the red rail (A. bonasia) of Mauritius, but they are commonly kept separate. Their relationship with other rails is unclear. It was described as having grey plumage, a red beak, red legs, and a naked red patch around the eye. The beak varied between specimens from straight to curved, but the reason for this is unknown. It was described as being attracted to red objects, which humans exploited while hunting it.

The Rodrigues rail is believed to have become extinct in the mid-18th century because of destruction of its habitat and predation by humans and introduced animals. Apart from information gathered from subfossil bones, the bird is poorly understood and is only known from two contemporaneous descriptions, but no contemporary illustrations. The bird was first mentioned by François Leguat, a French Huguenot refugee marooned on Rodrigues in 1691, and was named leguati in his honour. The second account was by Julien Tafforet, also marooned on the island in 1726. Subfossil remains were later discovered and connected with the old accounts.

Taxonomy

A line drawing of two flightless birds, each with an ovoid body, long neck and pointed bill
Schlegel's 1854 outlines of dodos, the second supposedly from Rodrigues, which were actually red rails from Mauritius

In 1848, the English zoologist Hugh Strickland called attention to a bird mentioned in the French traveller François Leguat's 1708 memoir about his stay on Rodrigues. Leguat referred to the birds as "gelinottes" (translated as "wood-hens"), a name Strickland thought implied the grouse (Tetraoninae) of Europe, though this was not consistent with the form of the beak described by Leguat. Strickland was unable to classify the bird further, but noted similarities with the dodo (Raphus cucullatus) and kiwi (Apteryx), based on unidentified birds from Mauritius illustrated by the travellers Pieter van den Broecke and Sir Thomas Herbert, which he thought related. Strickland also noted similarities with a bird from Mauritius, which would later be identified as the red rail (Aphanapteryx bonasia).[2][3]

In 1874, the French zoologist Alphonse Milne-Edwards connected Leguat's account with three subfossil bones (a sternum, a tarsometatarsus, and a fragmentary skull) found in a cave on Rodrigues, and recognised their similarity to those of the red rail. Milne-Edwards coined the generic name Erthyromachus from the Greek words for "red" and "battle" (also translated as "hostile to red"), in reference to its behaviour towards red objects, and the specific name is in honour of Leguat. The name Erthyromachus was incorrectly explained as referring to the Erythraean sea by Charles W. Richmond in 1908.[4][3] The name Miserythrus, from "red" and "hatred", was used by the English ornithologist Alfred Newton in 1874 (originally only in a manuscript), and also refers to the rail's behaviour towards red, but as a newer name, it is a junior synonym.[3]

In 1875, A. Newton also identified a reference to the bird in the 1726 account of the French traveller Julien Tafforet, which had then recently been rediscovered.[5] In 1879, more fossils, including skulls, were described by the zoologists Albert Günther and Edward Newton (brother of Alfred), who confirmed that the bird was a rail (rallidae). [6] The American ornithologist James Greenway suggested that Leguat's description referred to wind-blown purple swamphens (Porphyrio).[7] This has not been accepted by other authors.[8] More remains of the Rodrigues rail were found in 1974.[9]

Unlike the red rail and other extinct Mascarene birds, the Rodrigues rail was not illustrated by contemporaneous artists. The American ornithologist Storrs L. Olson described reconstructions made for the British zoologist Walter Rothschild's 1907 book Extinct Birds and the Japanese ornithologist Masauji Hachusika's 1953 book The Dodo and Kindred Birds as "rather fanciful".[3] The English artist Frederick William Frohawk based his restoration in the former book on an outline illustration, which was in turn based the sketch drawn by Herbert, which is now known to depict the red rail.[10] The German zoologist Hermann Schlegel thought it depicted a species of dodo (which he called Didus herbertii) from Rodrigues when he drew the outline in 1854, and that it was the species mentioned by Leguat.[11]

Evolution

Apart from being a close relative to the red rail, the relationships of the Rodrigues rail are uncertain and the two are commonly listed as separate genera, Aphanapteryx and Erythromachus, but have sometimes been united as species of Aphanapteryx.[12] Günther and A. Newton first generically synonymised the two in 1879 because of their skeletal similarities.[6] In 1977, Olson stated that though the two species were similar and derived from the same stock, they had also diverged considerably, and should possibly be kept in separate genera. Based on geographic location and the morphology of the nasal bones, Olson suggested that they were related to the genera Gallirallus, Dryolimnas, Atlantisia, and Rallus.[3] Rails have reached many oceanic archipelagos, which has frequently led to speciation and evolution of flightlessness. According to the British researchers Anthony S. Cheke and Julian P. Hume, the fact that the red rail lost much of its feather structure indicates it was isolated for a long time. These rails may be of Asian origin, like many other Mascarene birds.[12]

In 1892, the Scottish naturalist Henry Ogg Forbes described Hawkins's rail, an extinct species of rail from the Chatham Islands, as a new species of Aphanapteryx; A. hawkinsi. He found the Chatham Islands species more similar to the red rail than the latter was to the Rodrigues rail, and proposed that the Mascarene Islands had once been connected with the Chatham Islands. These ideas were later criticised by writers such as the British palaeontologist Charles W. Andrews and the German ornithologist Hans F. Gadow, and the bird was moved to its own genus, Diaphorapteryx.[13][14][15]

Description

An illustration of a bird with a long neck, a long, sharp, red bill, red legs and feet, mid-grey to black feathers and a large, red, naked area around its eye
Frohawk's 1907 restoration, based on a tracing of an old outline illustration and a description

The Rodrigues rail was a plump, flightless rail with bright grey plumage, perhaps flecked with white, and it had a red bill and legs, and a red, naked area around its eyes. It was somewhat smaller than its closest relative, the red rail. The bird's exact length is unknown, but it was about the size of a chicken. The strong bill varied greatly in size and shape; some specimens had short and almost straight bills, and others had much longer bills that were prominently curved.[8] It is unknown whether this was related to sexual dimorphism or to individual variation. Its cranium was 38 millimetres (1.5 in) long by 20 millimetres (0.79 in) wide, and the bill was 77 millimetres (3.0 in) long. The pelvis was large and strongly built in proportion to the size of the bird.[6]

The Rodrigues rail had somewhat larger wings than the red rail, but the species' leg proportions, pelvis and sacrum were similar.[6][16] The Rodrigues rail also differed from the red rail by having a proportionately longer humerus, a broader and shorter skull, and longer and lower nostrils, as well as a considerably different plumage, based on early descriptions.[3]

Contemporary accounts

1708 map of Rodrigues, decorated with solitaire birds
Leguat's 1708 map of Rodrigues

The Rodrigues rail was first recorded by François Leguat in his 1708 memoir, A New Voyage to the East Indies. Leguat was the leader of a group of nine French Huguenot refugees; the group were the first to colonise Rodrigues from 1691 to 1693, after they were marooned there by their captain.[8][17] Leguat's observations are considered some of the first cohesive accounts of animal behaviour in the wild.[12]

Leguat's full account of the bird reads as follows:

Our 'gelinotes' are fat all the year round and of a most delicate taste. Their colour is always of a bright grey, and there is very little difference in plumage between the two sexes. They hide their nests so well that we could not find them out, and consequently did not taste their eggs. They have a red naked area round their eyes, their beaks are straight and pointed, near two and two-fifths inches long, and red also. They cannot fly, their fat makes them too heavy for it. If you offer them anything red, they are so angry they will fly at you to catch it out of your hand, and in the heat of the combat we had an opportunity to take them with ease.[10]

Another description of appearance and behaviour is found a document called Relation de l'Ile Rodrigue attributed to Julien Tafforet, who was marooned on Rodrigues in 1726:

There is a sort of bird, of the size of a young hen, which has the beak and feet red. Its beak is a little like that of a curlew, excepting that it is slightly thicker and not quite so long. Its plumage is spotted with white and grey. They generally feed on the eggs of the land tortoises, which they find in the ground, which makes them so fat that they often have difficulty running. They are very good to eat, and their fat is of a yellowish red, which is excellent for pains. They have small pinions [wings], without feathers, on which account they cannot fly; but on the other hand, they run very well. Their cry is a continual whistling. When they see any one who pursues them they produce another sort of noise, like that of a person who has hiccups.[12]

Behaviour and ecology

An illustration of bird bones laid out in vertical rows
First known remains, 1874

According to the contemporary accounts, the Rodrigues rail ate invertebrates, possibly small vertebrates, and in the nesting season of the now extinct Cylindraspis tortoises, they dug up and fattened themselves on their eggs. It is possible that the birds had an annual cycle of becoming fat and slim, corresponding with varying availability of food throughout the year. Its vocalizations were a continuous whistling, and it had a hiccup-like, staccato alarm call.[18] They had no fear of humans because they had evolved in the absence of predators, enabling hunters to catch them in large numbers. Neither Leguat or Tafforet located the eggs and nests of the birds.[12] According to Milne-Edwards, the bird had legs "made for running".[10]

Many other species endemic to Rodrigues became extinct after humans arrived, and the island's ecosystem is heavily damaged. Before humans arrived, forests covered the island entirely, but very little remains today. The Rodrigues rail lived alongside other recently extinct birds, such as the Rodrigues solitaire (Pezophaps solitaria), the Rodrigues parrot (Necropsittacus rodricanus), Newton's parakeet (Psittacula exsul), the Rodrigues starling (Necropsar rodericanus), the Rodrigues owl (Mascarenotus murivorus), the Rodrigues night heron (Nycticorax megacephalus), and the Rodrigues pigeon (Nesoenas rodericanus). Extinct reptiles include the domed Rodrigues giant tortoise (Cylindraspis peltastes), the saddle-backed Rodrigues giant tortoise (Cylindraspis vosmaeri), and the Rodrigues day gecko (Phelsuma edwardnewtoni).[12]

Extinction

The disappearance of the Rodrigues rail coincided with the tortoise trade between 1730 and 1750; traders burnt vegetation, hunted birds, and imported cats and pigs which preyed on eggs and chicks. The fat of birds that had been feeding on tortoise eggs was bright orange and was used as a remedy for people recovering from illness.[12] Although the Rodrigues rail survived predation by rats that were accidentally introduced in the late 17th century and had multiplied by the time of Leguat's visit, it was unable to withstand persecution by humans. The French astronomer Alexandre Guy Pingré wrote in his 1763 report that the bird was extinct by 1761.[18]

References

  1. ^ BirdLife International (2016). "Erythromachus leguati". IUCN Red List of Threatened Species. Version 2006. International Union for Conservation of Nature. Retrieved 1 October 2016.CS1 maint: uses authors parameter (link)
  2. ^ 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". Reeve, Benham and Reeve: 55–56. doi:10.5962/bhl.title.43794. Cite journal requires |journal= (help)
  3. ^ a b c d e f Olson, S. (1977). "A synopsis on the fossil Rallidae". In Ripley, S. D. (ed.). Rails of the World – A Monograph of the Family Rallidae. Boston: Codline. pp. 357–363. ISBN 0-87474-804-6.
  4. ^ Milne-Edwards, A. (1866–1873). Recherches sur la faune ornithologique éteinte des iles Mascareignes et de Madagascar (in French). Paris: G. Masson. pp. 23–34.
  5. ^ Newton, A. (1875). "Additional evidence as to the original fauna of Rodriguez". Proceedings of the Zoological Society of London: 39–43.
  6. ^ a b c d Günther, A.; Newton, E. (1879). "The extinct birds of Rodriguez". Philosophical Transactions of the Royal Society of London. 168: 423–437. doi:10.1098/rstl.1879.0043.
  7. ^ Greenway, J. C. (1967). Extinct and Vanishing Birds of the World. New York: American Committee for International Wild Life Protection. pp. 117–119. ISBN 0486218694.
  8. ^ a b c Fuller, E. (2001). Extinct Birds (revised ed.). Comstock. pp. 149–151. ISBN 0-8014-3954-X.
  9. ^ Cowles, G. S. (1987). "The fossil record". In Diamond, A. W. (ed.). Studies of Mascarene Island Birds. Cambridge. pp. 90–100. doi:10.1017/CBO9780511735769.004. ISBN 9780511735769.
  10. ^ a b c Rothschild, W. (1907). Extinct Birds. London: Hutchinson & Co. p. 135.
  11. ^ 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
  12. ^ a b c d e f g Cheke, A. S.; Hume, J. P. (2008). Lost Land of the Dodo: an Ecological History of Mauritius, Réunion & Rodrigues. New Haven and London: T. & A. D. Poyser. pp. 49–52. ISBN 978-0-7136-6544-4.
  13. ^ Forbes, H. O. (1893). "Mr. H. O. Forbes's discoveries in the Chatham Islands". Nature. 48 (1230): 74–75. Bibcode:1893Natur..48...74F. doi:10.1038/048074c0.
  14. ^ Forbes, H. O. (1893). "Mr. H. O. Forbes's discoveries in the Chatham Islands". Nature. 48 (1232): 126–126. Bibcode:1893Natur..48..126F. doi:10.1038/048126a0.
  15. ^ Andrews, C. W. (1896). "On the extinct birds of the Chatham Islands. Part I.: The osteology of Diaphorapteryx hawkinsi". Novitates Zoologicae. 73–84: 72.
  16. ^ Newton, E.; Gadow, H. (1893). "IX. On additional bones of the Dodo and other extinct birds of Mauritius obtained by Mr. Theodore Sauzier". The Transactions of the Zoological Society of London. 13 (7): 281–302. doi:10.1111/j.1469-7998.1893.tb00001.x.
  17. ^ Leguat, F. (1891). Oliver, S. P. (ed.). The voyage of François Leguat of Bresse, to Rodriguez, Mauritius, Java, and the Cape of Good Hope. Volume 1. London: Hakluyt Society. p. 81.
  18. ^ a b Hume, J. P.; Walters, M. (2012). Extinct Birds. A & C Black. p. 110. ISBN 140815725X.

External links