Lord Howe swamphen

Lord Howe swamphen
PorphyrioAlbus.jpg
Illustration probably based on a live specimen, by Peter Mazell, published in Arthur Phillip's 1789 book

Extinct  (probably by 1834) (IUCN 3.1)[1]
Scientific classification
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Species:
P. albus
Binomial name
Porphyrio albus
(White, 1790)
Lord Howe Island.PNG
Location of Lord Howe Island
Synonyms

The Lord Howe swamphen (Porphyrio albus), also known as the Lord Howe gallinule, white swamphen, or white gallinule, is an extinct species of rail that lived on Lord Howe Island, east of Australia. It was first encountered when the crews of British ships visited the island between 1788 and 1790, and all contemporary accounts and illustration were produced during this time. Today, two specimens exist, the holotype in the Natural History Museum of Vienna, and the one in World Museum, Liverpool. There has historically been confusion over the provenance of the specimens and the classification and anatomy of the bird, but it is today thought to have been a distinct species endemic to Lord Howe Island, and to have been most similar to the Australasian swamphen.

The Lord Howe swamphen was 36 cm (14 in) to 55 cm (22 in) long. Both known skins have mainly white plumage, unlike other swamphens, but contemporary accounts indicate that there were birds with all-white, all-blue, and mixed blue and white plumage. The chicks were black, becoming blue, and then white as they aged. This has historically been interpreted as being due to albinism, but may instead be progressive greying, where feathers lose their pigment with age. The bill, frontal shield, and legs of the bird were red, and it had a claw or spur on its wing. Little was recorded about the bird's behaviour. Though it may not have been flightless, it was probably a bad flier. Combined with its tameness, it was easy prey for visiting humans, who killed it with sticks. Though it was said to be common, the species may have been hunted to extinction before 1834, when Lord Howe Island was settled.

Taxonomy

Illustration of the Vienna holotype specimen by Sarah Stone, featured in John White's 1790 book wherein the species was named

Lord Howe Island is a small, remote island that lies about 600 kilometres (370 mi) east of Australia. Ships first arrived on the island in 1788, including two which were supplying the British penal colony on Norfolk Island, and three transport ships of the British First Fleet. When HMS Supply passed by the island, the commander of the ship named it after Richard Howe, the First Lord of the Admiralty. Crews of the visiting ships captured native birds, including Lord Howe swamphens, and all contemporary descriptions and depictions of the species were made between 1788 and 1790. The bird was first mentioned by the Master of HMS Supply, David Blackburn, in a 1788 letter to his friend. Other accounts and illustrations were produced by men such as Arthur Bowes Smyth (who drew the first known illustration of the species), naval officer and surgeon of the fleet, Arthur Phillip, governor of New South Wales, and George Raper, the Midshipman of HMS Sirius. A number of second hand accounts also exist, and at least ten contemporary illustrations are known. These accounts indicate that the population was variable, with the plumage of individuals being all-white, all-blue, or mixed blue and white.[2][3]

In 1790 the Lord Howe swamphen was scientifically described and named by the surgeon John White, in a book about his time in New South Wales. He named the bird Fulica alba, and the specific name is derived from the Latin word for white, albus. White apparently never visited Lord Howe Island himself, but may have questioned sailors and based some of his description on earlier accounts. White stated he had described a skin at the Leverian Museum, and his book included an illustration of the specimen by the illustrator Sarah Stone. It is uncertain when and how the specimen arrived at the museum. This skin, the holotype specimen of the species, was purchased by the Natural History Museum of Vienna in 1806, where it is today catalogues as specimen NMW 50.761. The naturalist John Latham listed the bird as Gallinula alba in a later 1790 work.[4][2][5][6]

One other Lord Howe swamphen specimen is known, held in World Museum, Liverpool, where it is catalogued as specimen WML D3213. It was obtained by the naturalist Joseph Banks, later entered the collection of the traveller William Bullock, and was purchased by Lord Edward Smith-Stanley, 12th Earl of Derby, whose son donated it to the public museums of Liverpool in 1850. Though White stated the first specimen had been obtained from Lord Howe Island, the provenance of the second specimen has historically been unclear (it was originally said to have come from New Zealand), which resulted in taxonomic confusion. Phillip stated the bird could also be found on Norfolk Island and other places, while Latham claimed it could only be found on Norfolk Island, and when the first specimen was sold by the Leverian Museum, it was listed as coming from New Holland (which Australia was called at the time), perhaps because it had been sent from Sydney.[2][6]

The Vienna specimen depicted as similar to a takahē, by John Gerrard Keulemans, 1873

In the 19th century, some writers concluded that the Lord Howe swamphen was an albino variety of the Australasian swamphen (Porphyrio melanotus). The zoologist Coenraad Jacob Temminck assigned it to the swamphen genus Porphyrio as P. albus in 1820, and the zoologist George Robert Gray referred to it as P. melanotus varius alba in 1844. Several writers also failed to notice that White had given Lord Howe Island as the origin of the Vienna specimen. In 1860 the ornithologist August von Pelzeln thought the Vienna specimen had come from Norfolk Island, and assigned the species to the genus Notornis as N. alba, along with the takahē (P. hochstetteri) of New Zealand, which was placed in that genus at the time. In 1873 The naturalist Osbert Salvin agreed that the Lord Howe bird was similar to the takahē, though he had apparently never seen the Vienna specimen, basing his conclusion on a drawing of it provided by Pelzeln. Salvin included a takahē-like illustration of the Vienna specimen by the artist John Gerrard Keulemans in his article, based on Pelzeln's drawing.[2][7][8][9][10] The bird was also inaccurately stated to have lived on Ball's Pyramid, an islet off Lord Howe Island.[11]

In 1875 the ornithologist George Dawson Rowley noted differences between the Vienna and Liverpool specimens, and erected a new species based on the latter, P. stanleyi, named after Lord Stanley. He believed the Liverpool specimen was a juvenile, and that it had come from Lord Howe Island or New Zealand, and maintained the belief that the Vienna specimen was from Norfolk Island. In spite of naming the new species, he also considered the idea that P. stanleyi was an albino Australasian swamphen. Rowley also considered the Vienna bird to be more similar to the takahē. In 1901, the ornithologist Henry Ogg Forbes found the Vienna and Liverpool specimens similar enough to each other to belong to the same species, N. alba. In 1907 the zoologist Walter Rothschild considered the two species distinct from each other, but places them both in the genus Notornis. He thought the image published by Phillip in 1789 depicted N. stanleyi from of Lord Howe Island, whereas the image published by White in 1790 showed N. alba of Norfolk Island. Rothschild disagreed that the specimens were albinos, but birds in a stage of evolution towards becoming a white species. He also published an illustration of N. alba by Keulemans which was similar to a takahē, which featured dark primary feathers, though the Vienna specimen it was based on is all white.[6][12][2][10]

In 1910 the ornithologist Tom Iredale demonstrated that there was no proof of the Lord Howe swamphen having occurred anywhere but on Lord Howe Island. He noted the capable observers Johann Reinhold Forster and his son Georg Forster had not reported seeing such birds when they visited Norfolk Island in.[13] In 1913, after examining the Vienna specimen, Iredale concluded that the bird belonged in the genus Porphyrio, and did not resemble the takahē.[14] In 1928 the ornithologist Gregory Mathews found a 1790 painting by Raper different enough from P. albus that he named a new species based on it, P. raperi. He also considered P. albus distinct enough to warrant a new genus, Kentrophorina, due to the presence of a wing claw. In 1936, he conceded that P. raperi was a synonym of P. albus.[2]

Illustration of the Liverpool specimen, the holotype of P. stanleyi, a junior synonym of P. albus, by Keulemans, 1875

The ornithologist Keith Alfred Hindwood agreed that P. stanleyi was an albino of P. melanotus in 1932, and in 1940, he found P. albus to be so closely related to P. melanotus that he considered them subspecies of the same species, as P. albus albus and P. albus melanotus (since albus is the older name). Hindwood suggested that the population on Lord Howe Island was white, and but that blue Australasian swamphens occasionally arrived and bred with the white birds. He also pointed out that Australasian swamphens are prone to white feathering.[2][15][3] In 1941 the biologist Ernst Mayr proposed that the Lord Howe swamphen was simply a partially albinistic population of Australasian swamphens. He proposed that the blue swamphens remaining on Lord Howe Island had survived because they were less conspicuous than the white ones.[16] In 1967, the ornithologist James Greenway also considered the a subspecies, with P. stanleyi as a synonym.[17] In 1991 the ornithologist Ian Hutton reported subfossil bones of the Lord Howe swamphen. He also agreed that the birds described as having both white and blue feathers were hybrids between the Lord Howe swamphen and the Australasian swamphen, and idea which was also considered by the ornithologists Barry Taylor and Ber van Perlo in 2000.[18]

In 2015, the biologists Juan C. Garcia-R. and Steve A. Trewick analysed the DNA of the purple swamphens, and found that the Lord Howe swamphen was most closely related to the Philippine swamphen (P. pulverulentus), with the black-backed swamphen (P. indicus) being closer related to them to other species of its region. They used DNA from the Vienna specimen, but were unable to obtain usable DNA from the Liverpool specimen. They suggested that the Lord Howe island may have descended from a small number of migrant Philippine swamphens during the late Pleistocene (about 500.000 years ago), by dispersing over other island. This indicates a complex history, since their lineages are not recorded on the islands between them, and they admitted that such results based on such ancient DNA sources should be treated with caution. Though many purple swamphen taxa had earlier been considered subspecies of the species Porphyrio porphyrio (wherein other purple swamphens were placed as subspecies), they found this to be a paraphyletic, unnatural grouping, since they found different species to group among the subspecies.[19][2]

The Australasian swamphen is anatomically similar to this species

In 2016 the ornithologists Hein van Grouw and Julian P. Hume concluded that many of the old accounts had errors in regard to the provenance of the bird, that it was endemic to Lord Howe Island, and suggested when the specimens had been collected (both between March and May 1788), by who, and how they arrived in England. They agreed that the Lord Howe swamphen was a valid species, after reconstructing the colouration of juvenile birds before turning white, which was distinct from other swamphens. They found the Lord Howe swamphen anatomically more similar to the Australasian swamphen than the Philippine swamphen, and suggested that studies with more complete datasets than the earlier DNA work may show different results. Due to their anatomical similarities, the closer geographic proximity, and the fact that Australasian swamphens have recolonised both Lord Howe and Norfolk Island, they found it more likely that the Lord Howe swamphen was descended from Australasian swamphens.[2]

Description

Illustration by Henrik Grönvold, 1928

The length of the Lord Howe swamphen has been given as 36 cm (14 in) and 55 cm (22 in) long, and it was similar to the Australasian swamphen in size. The wings of the Lord Howe swamphen were the proportionally shortest of all swamphens. The wing of the Vienna specimen is 218 mm (9 in) mm long, the tail is 73.3 mm (3 in), the culmen with its frontal shield (the fleshy plate on the head) is 79 mm (3 in), the tarsus is 86 mm (3 in), and the middle toe is 77.7 mm (3 in) long. The wing of thy Liverpool specimen is 235 mm (9 in) long, the tarsus is 88.4 mm (3 in), the middle toe is 66.5 mm (3 in), but the tail and the beak are damaged, and can therefore not be reliably measured. The Lord Howe swamphen differed from most other swamphens, except the Australasian swamphen, in having a short middle toe, whereas it is the same length as the tarsus or longer in other species. Its tail was also the shortest. Both specimens have a claw or spur on their wings; it is longer and more discernible in the Vienna specimen, whereas it is sharp and buried under the feathers of the Liverpool specimen. This feature is variable within other types of swamphen.[11][20][2] The soft retrice feathers and and the relative lengths of the secondary feathers and wing covert feathers in relation to the primary feathers distinguish it from other species, and these features appear to have been intermediate between purple swamphens the takahē. [18]

The known skins are mainly white, but contemporary illustrations show that some individuals were blue, while some had a mix of both white and blue feathers. The legs were red or yellow, though the latter colour may only have been present on the legs of dried specimens. The bill and shield were red, and the iris was red or brown. According to the notes written on an illustration by an unknown artist (in the collection of the artist Thomas Watling), the chicks were black, and became bluish grey, and finally pure white as they matured. While the Vienna specimen is pure white, the Liverpool specimen has blackish blue feathers on the head and neck (concentrated near the upper surface of the shield), blue feathers on the breast, and purplish blue feathers on the shoulders and back. This indicates that the Liverpool specimen was a younger bird than the Vienna specimen, and that the latter had reached the final stage of maturity. It also has yellowish reflections on its neck and breast. Since the Liverpool specimen preserves some of its original colouration, van Grouw and Hume were able to reconstruct its natural colouration before becoming white. It differed from other swamphens in having blackish blue lores, forehead, crown, nape and hind neck, purple blue mantle, back, and wings, a darker rump and upper tail covert feathers, and dark greyish blue underparts.[11][20][2][18][21]

Illustration by an unknown artist (in the collection of Thomas Watling) showing three colour stages of this bird

Phillip gave a detailed description in 1789, possibly based on a live bird he had received in Sydney:

This beautiful bird greatly resembles the purple Gallinule in shape and make, but is much superior in size, being as large as a dunghill fowl. The length from the end of the bill to that of the claws is two feet three inches; the bill is very stout, and the colour of it, the whole top of the head, and the irides red; the sides of the head around the eyes are reddish, very thinly sprinkled with white feathers; the whole of the plumage without exception is white. The legs the colour of the bill. This species is pretty common on Lord Howe’s Island, Norfolk Island, and other places, and is a very tame species. The other sex, supposed to be the male, is said to have some blue on the wings.[2]

The Vienna specimen is today a cabinet skin, with its legs outstretched, but van Grouw and Hume suggested that Stone's 1790 illustration showed the original mounted pose. It is in good condition, and though the legs are faded to a pale orange brown, they were probably reddish in the living bird. It has no yellowish or purple feathers, unlike what was claimed by Rothschild. Forbes suggested that the Liverpool specimen had been "remade" and mounted after Stone's illustration, though its pose is dissimilar. Keuleman's illustration of the mount shows the present pose, so either Forbes was incorrect, or the new pose was based in Keuleman's image. The Liverpool specimen is in good condition, though it has suffered extensive loss of feathers on its head and neck. The bill is broken, and is lacking its entire rhamphotheca (the horny covering of the bill); the underlying bone has been painted red to simulate an undamaged bill, which has historically caused some confusion. The legs have also been painted red, and there is no indication of their original colouration. The reason why only white specimens are known today may be due to collecting bias, as unusually coloured specimens are more likely to be collected than those of normal colour.[2][18][20][12][21]

Behaviour and ecology

Illustration of a presumably live bird by George Raper, 1790; the junior synonym P. raperi is based on this image

The Lord Howe swamphen inhabited wooded lowland areas in wetlands. Nothing was recorded about its social and reproductive behaviour, its nest and eggs were never described, and neither was its call. It was presumably not migratory.[18] Blackburn's 1788 account is the only one that mentions the diet of this bird:

…on the shore we caught several sorts of birds, … and a white fowl – something like a Guinea hen, with a very strong thick & sharp pointed bill of a red colour – stout legs and claws – I believe they are carnivorous they hold their food between the thumb or hind claw & the bottom of the foot & lift it to the mouth without stopping so much as a parrot.[2]

Some contemporary accounts indicated that the bird was flighltess. Rowley considered the Liverpool specimen (representing the separate species P. stanleyi) capable of flight, due to its longer wings, while Rotschild stated that both were flightless (though he contradicted himself on whether their wings were the same lengths). Some observes authors claimed that the Lord Howe swamphen was fligtless. Van Grouw and Hume found that both specimens showed evidence of an increased terrestrial lifestyle and being in the process of becoming flightless. This includes decreased length of the wings, more robust feet and short toes. It may therefore still have been capable of flight, though behaviourally flightless, which is also the case of other island endemic birds, such as some parrots. Though the Lord Howe swamphen was similar in size to the Australasian swamphen, it had proportionally shorter wings, and therefore a higher wing load, perhaps the highest of all swamphens.[2][10][6]

Illustration of one white and one still variegated individual, by Raper, 1790

Van Grouw and Hume pointed out that white colour aberration in birds is rarely caused by albinism (which is less common than formerly believed), but rather by leucism or progressive greying, a phenomenon van Grouw had earlier described in 2012 and 2013. These conditions produce white feathers due to the absence of cells that produce the pigment melanin. Leucism is inherited, and the white feathering is therefore present in juveniles and does not change with age, but progressive feathering causes normally coloured juveniles to lose pigment-producing cells with age, and they therefore become white. Since contemporary accounts indicate that the Lord Howe swamphen turned from black to bluish grey and then white, Van Grouw and Hume concluded that it underwent inheritable progressive greying. Progressive greying is a common cause for white feathers in many types of birds, including various rails, though such specimens have sometimes been inaccurately referred to as albinos. The condition does not affect carotenoid pigments (red and yellow), and therefore the bill and legs of the Lord Howe swamphens retained their colouration. The large number of white Lord Howe swamphens may be due to the founding population of the species having been small, which would have spread inhabitable progressive greying among them.[2][5][21]

Extinction

Illustration showing the Vienna specimen as similar to a takahē, with inaccurately dark primary feathers, by Keulemans, 1907

Though the Lord Howe swamphen was considered common in the late 18th century, it appears to have disappeared quickly. The span from when the island was discovered to the last mention of living birds is only two years, 1788–90. It had probably disappeared before 1834, when Lord Howe Island was first settled, or within the following ten years. Earlier, whalers and sealers had used the island for supplies, and may have hunted the bird to extinction. Habitat destruction did probably not play a role in its extinction, and predators such as rats and cats only arrived later on the island.[11][18][2] Several contemporary accounts stress the ease of which the various birds of Lord Howe Island were hunted, and the large number that could be taken for ship's provisions.[3]

In 1789 White described how the Lord Howe swamphen could be caught as follows:

They [sailors] also found on it, in great plenty, a kind of fowl, resembling much of the Guinea fowl in shape and size, but widely different in colour; they being in general all white, with a red fleshy substance rising, like a cock’s comb, from the head, and not unlike a piece of sealing-wax. These not being birds of flight, nor in the least wild, the sailors availing themselves of their gentleness and inability to take wing from their pursuits, easily struck them down with sticks.[2]

Illustration of three live birds by Arthur Bowes Smyth, ca. 1788; the first known illustration of the species

The fact that they could be killed with sticks may be due to their poor flight ability, which would have made them vulnerable upon the arrival of humans. They were very tame and curious, since they know no enemies, due to lack of natural predators on the island.[20][3][2] The doctor John Foulis, who undertook an ornithological survey on the island in the mid-1840s did not mention the bird, so it must have been extinct by this time.[11] In 1909 the writer Arthur Francis Basset Hull expressed hope that the bird still survived in unexplored mountains.[22]

Since Lord Howe Island was discovered, eight kinds of bird have become extinct due to human interference, including the Lord Howe pigeon (Columba vitiensis godmanae), the Lord Howe parakeet (Cyanoramphus subflavescens), the Lord Howe gerygone (Gerygone insularis), the Lord Howe fantail (Rhipidura fuliginosa cervina), the Lord Howe thrush (Turdus poliocephalus vinitinctus), the robust white-eye (Zosterops strenuus), and the Lord Howe starling (Aplonis fusca hulliana). The extinction of so many native birds is akin to what occurred on several other islands, such as the Mascarenes.[3]

See also

References

  1. ^ BirdLife International (2012). "Porphyrio albus". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
  2. ^ a b c d e f g h i j k l m n o p q r s van Grouw, H.; Hume, J. (2016). "The history and morphology of Lord Howe Gallinule or Swamphen Porphyrio albus (Rallidae)" (PDF). Bulletin of the British Ornithologists' Club. 136 (3): 172–198.
  3. ^ a b c d e Hindwood, K. A. (1940). "The birds of Lord Howe Island". Emu - Austral Ornithology. 40 (1): 1–86. doi:10.1071/MU940001.
  4. ^ White, J. (1790), Journal of a voyage to New South Wales with sixty-five plates of non descript animals, birds, lizards, serpents, curious cones of trees and other natural productions, London: J. Debrett, also at Project Gutenberg Australia
  5. ^ a b van Grouw, H. (2013). "What colour is that bird? The causes and recognition of common colour aberrations in birds". British Birds. 106 (1–56): 17–29.
  6. ^ a b c d Rowley, G. D. (1876). Ornithological miscellany. London: Trübner and Co., Bernard Quaritch, R.H. Porter. pp. 36–48.
  7. ^ Plezeln, A. (1873). "On the birds in the imperial collection at Vienna obtained from the Leverian Museum". Ibis. 15 (2): 105–124. doi:10.1111/j.1474-919X.1873.tb05883.x.
  8. ^ Pelzeln, A. (1860). "Zur ornithologie der Insel Norfolk". Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften (in German). 41: 319–332.
  9. ^ Salvin, O. (1873). "Note on the Fulica alba of White". Ibis. 15 (3): 295–295. doi:10.1111/j.1474-919X.1873.tb05905.x.
  10. ^ a b c Rothschild, W. (1907). Extinct Birds. London: Hutchinson & Co. pp. 143–144.
  11. ^ a b c d e Hume, J. P.; Walters, M. (2012). Extinct Birds. A & C Black. pp. 114–116. ISBN 978-1-4081-5725-1.
  12. ^ a b Forbes, H. O. (1901). "Note on Lord Stanley's Water Hen". Bulletin of the Liverpool Museums. 3 (2): 62–68.
  13. ^ Iredale, T. (1911). "An additional note on the birds of Lord Howe and Norfolk Islands". Proceedings of the Linnean Society of New South Wales. 35: 773–782. doi:10.5962/bhl.part.25558.
  14. ^ Iredale, T. (1913). "On some interesting birds in the Vienna Museum". Austral Avian Record. 2 (1): 14–32.
  15. ^ Hindwood, K. A. (1932). "An historic diary". Emu - Austral Ornithology. 32 (1): 17–29. doi:10.1071/MU932017.
  16. ^ Mayr, E. (2016). "Taxonomic notes on the birds of Lord Howe Island". Emu - Austral Ornithology. 40 (4): 321–322. doi:10.1071/MU940321.
  17. ^ Greenway, J. C. (1967). Extinct and Vanishing Birds of the World. New York: American Committee for International Wild Life Protection. pp. 244–253. ISBN 978-0-486-21869-4.
  18. ^ a b c d e f Taylor, B.; van Perlo, B. (2000). Rails. Robertsbridge, Sussex: Pica. pp. 470–471. ISBN 978-1-873403-59-4.
  19. ^ Garcia-R., J. C.; Trewick, S. A. (2015). "Dispersal and speciation in purple swamphens (Rallidae: Porphyrio)". The Auk. 132 (1): 140–155. doi:10.1642/AUK-14-114.1.
  20. ^ a b c d Fuller, E. (2001). Extinct Birds (revised ed.). Comstock. pp. 141–145. ISBN 978-0-8014-3954-4.
  21. ^ a b c Hume, J. P.; van Grouw, H. (2014). "Colour aberrations in extinct and endangered birds" (PDF). Bulletin of the British Ornithologists' Club. 134: 168–193.
  22. ^ Hull, A. F. B. (1909). "The birds of Lord Howe and Norfolk Islands". Proceedings of the Linnean Society of New South Wales. 34: 636–693.