The white swamphen (Porphyrio albus), also known as the white gallinule, the Lord Howe swamphen or the Lord Howe gallinule, is an extinct species of rail which 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 illustrations were produced during this time. Today, two skins exist: the holotype in the Natural History Museum of Vienna, and another in Liverpool's World Museum. Although historical confusion has existed about the provenance of the specimens and the classification and anatomy of the bird, it is now thought to have been a distinct species endemic to Lord Howe Island and most similar to the Australasian swamphen. Subfossil bones have also been discovered since.
The white swamphen was long. Both known skins have mainly-white plumage, although the Liverpool specimen also has dispersed blue feathers. This is unlike other swamphens, but contemporary accounts indicate birds with all-white, all-blue, and mixed blue-and-white plumage. The chicks were black, becoming blue and then white as they aged. Although this has been interpreted as due to albinism, it may have been progressive greying in which feathers lose their pigment with age. The bird's bill, frontal shield and legs were red, and it had a claw (or spur) on its wing. Little was recorded about the white swamphen's behaviour. It may not have been flightless, but was probably a poor flier. This and its docility made the bird easy prey for visiting humans, who killed it with sticks. Reportedly once common, the species may have been hunted to extinction before 1834, when Lord Howe Island was settled.
Taxonomy
Lord Howe Island is a small, remote island about east of Australia. Ships first arrived on the island in 1788, including two which supplied the British penal colony on Norfolk Island and three transport ships of the British First Fleet. When passed the island, the ship's commander named it after First Lord of the Admiralty Richard Howe. Crews of the visiting ships captured native birds (including white 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 a friend. Other accounts and illustrations were produced by Arthur Bowes Smyth, the fleet's naval officer and surgeon, who drew the first known illustration of the species; Arthur Phillip, governor of New South Wales; and George Raper, midshipman of . Secondhand accounts also exist, and at least ten contemporary illustrations are known. The accounts indicate that the population varied, and individual bird plumage was white, blue, or mixed blue-and-white.
In 1790, the white swamphen was scientifically described by the surgeon John White in a book about his time in New South Wales. The binomial name in White's book, Fulica alba, was provided by the English naturalist George Shaw. The specific name is derived from the Latin word for white (albus). White found the bird most similar to the western swamphen (Porphyrio porphyrio, then in the genus Fulica). Although he apparently never visited Lord Howe Island, White may have questioned sailors and based some of his description on earlier accounts. He said he had described a skin at the Leverian Museum, and his book included an illustration of the specimen by the artist 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 and is catalogued as specimen NMW 50.761. The naturalist John Latham listed the bird as Gallinula alba in a later 1790 work, and wrote that it may have been a variety of purple swamphen (or "gallinule").
One other white swamphen specimen is in Liverpool's World Museum, where it is catalogued as specimen NML-VZ D3213. Obtained by the naturalist Sir Joseph Banks, it later entered the collection of the traveller William Bullock and was purchased by Lord Stanley; Stanley's son donated it to Liverpool's public museums in 1850. Although White said that the first specimen was obtained from Lord Howe Island, the provenance of the second has been unclear; it was originally said to have come from New Zealand, resulting in taxonomic confusion. Phillip wrote that the bird could also be found on Norfolk Island and elsewhere, but Latham said it could be found only on Norfolk Island. 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 was sent from Sydney. A note by the naturalist Edgar Leopold Layard on a contemporary illustration of the bird by Captain John Hunter inaccurately stated that it only lived on Ball's Pyramid, an islet off Lord Howe Island.
The zoologist Coenraad Jacob Temminck assigned the white swamphen to the swamphen genus Porphyrio as P. albus in 1820, and the zoologist George Robert Gray considered it an albino variety of the Australasian swamphen (P. melanotus) as P. m. varius alba in 1844. The belief that the bird was simply an albino was held by several later writers, and many failed to notice that White cited Lord Howe Island as the origin of the Vienna specimen. In 1860 and 1873, the ornithologist August von Pelzeln said that the Vienna specimen had come from Norfolk Island, and assigned the species to the genus Notornis as N. alba; the takahē (P. hochstetteri) of New Zealand was also placed in that genus at the time. In 1873, the naturalist Osbert Salvin agreed that the Lord Howe Island bird was similar to the takahē, although he had apparently never seen the Vienna specimen, basing his conclusion on a drawing provided by von Pelzeln. Salvin included a takahē-like illustration of the Vienna specimen by the artist John Gerrard Keulemans, based on von Pelzeln's drawing, in his article.
In 1875, the ornithologist George Dawson Rowley noted differences between the Vienna and Liverpool specimens and named a new species based on the latter: P. stanleyi, named after Lord Stanley. He believed that the Liverpool specimen was a juvenile from Lord Howe Island or New Zealand, and continued to believe that the Vienna specimen was from Norfolk Island. Despite naming the new species, Rowley considered the possibility that P. stanleyi was an albino Australasian swamphen and considered the Vienna bird more similar to the takahē. In 1901, the ornithologist Henry Ogg Forbes had the Liverpool specimen dismounted so he could examine it for damage. Forbes found it similar enough to the Vienna specimen to belong to the same species, N. alba. The zoologist Walter Rothschild considered the two species distinct from each other in 1907, but placed them both in the genus Notornis. Rothschild thought that the image published by Phillip in 1789 depicted N. stanleyi from Lord Howe Island, and the image published by White in 1790 showed N. alba from Norfolk Island. He disagreed that the specimens were albinos, thinking instead that they were evolving into a white species. Rothschild published an illustration of N. alba by Keulemans where it is similar to a takahē, inaccurately showing it with dark primary feathers, although the Vienna specimen on which it was based is all white. In 1910, the ornithologist Tom Iredale demonstrated that there was no proof of the white swamphen existing anywhere but on Lord Howe Island and noted that early visitors to Norfolk Island (such as Captain James Cook and Lieutenant Philip Gidley King) did not mention the bird. In 1913, after examining the Vienna specimen, Iredale concluded that the bird belonged in the genus Porphyrio and did not resemble the takahē.
In 1928, the ornithologist Gregory Mathews discussed a 1790 painting by Raper which he thought differed enough from P. albus in proportions and colouration that he named a new species based on it: P. raperi. Mathews also considered P. albus distinct enough to warrant a new genus, Kentrophorina, due to having a claw (or spur) on one wing. In 1936, he conceded that P. raperi was a synonym of P. albus. The ornithologist Keith Alfred Hindwood agreed that the bird was an albino P. melanotus in 1932, and pointed out that the naturalists Johann Reinhold Forster and Georg Forster (his son) did not record the bird when Cook's ship visited Norfolk Island in 1774. In 1940, Hindwood found the white swamphen so closely related to the Australasian swamphen that he considered them subspecies of the same species: P. albus albus and P. albus melanotus (since albus is the older name). Hindwood suggested that the population on Lord Howe Island was white; blue Australasian swamphens occasionally arrived (stragglers from elsewhere have been found on the island) and bred with the white birds, accounting for the blue and partially-blue individuals in the old accounts. He also pointed out that Australasian swamphens are prone to white feathering. In 1941, the biologist Ernst Mayr proposed that the white swamphen was a partially-albinistic population of Australasian swamphens. Mayr suggested that the blue swamphens remaining on Lord Howe Island were not stragglers, but had survived because they were less conspicuous than the white ones. In 1967, the ornithologist James Greenway also considered the white swamphen a subspecies (with P. stanleyi a synonym) and considered the white individuals albinos. He suggested that the similarities between the wing feathers of the white swamphen and the takahē were due to parallel evolution in two isolated populations of reluctant fliers.
The ornithologist Sidney Dillon Ripley found the white swamphen to be intermediate between the takahē and the purple swamphen in 1977, based on patterns of the leg-scutes, and reported that X-rays of bones also showed similarities with the takahē. He considered only the Vienna specimen to be a white swamphen, whereas he considered the Liverpool specimen to be an albino Australasian swamphen (listing P. stanleyi as a junior synonym of that bird) from New Zealand. In 1991, the ornithologist Ian Hutton reported subfossil bones of the white swamphen. Hutton agreed that the birds described as having white-and-blue feathers were hybrids between the white swamphen and the Australasian swamphen, an idea also considered by the ornithologists Barry Taylor and Ber van Perlo in 2000. In 2000, the writer Errol Fuller said that since swamphens are widespread colonists, it would be expected that populations would evolve similarly to the takahē when they found refuges without mammals (losing flight and becoming bulkier with stouter legs, for example); this was the case with the white swamphen. Fuller suggested that they could be called "white takahēs", which had been alluded to earlier; the white birds may have been a colour morph of the population, or the blue birds may have been Australasian swamphens which associated with the white birds.