Invisible rail

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Invisible rail
HabroptilaWallaciiWolf.jpg
Adult by Joseph Wolf, 1859
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Gruiformes
Family: Rallidae
Genus: Habroptila
Gray, GR, 1861
Species:
H. wallacii
Binomial name
Habroptila wallacii
Gray, GR, 1861
Habroptila wallacii halmahera map.png
   Recent records
   pre-1950 records
   Kao town
Inset shows location of Halmahera within Indonesia
Synonyms

Gallirallus wallacii

The invisible rail, Wallace's rail, or drummer rail (Habroptila wallacii) is a large flightless rail that is endemic to the island of Halmahera in Northern Maluku, Indonesia, where it inhabits impenetrable sago swamps adjacent to forests. Its plumage is predominantly dark slate-grey, and the bare skin around its eyes, the long, thick bill, and the legs are all bright red. Its call is a low drumming sound which is accompanied by wing-beating. The difficulty of seeing this shy bird in its dense habitat means that information on its behaviour is limited.

Contents

Recorded dietary items include sago shoots and insects, and it also swallows small stones to help break up its food. It is apparently monogamous, but little else is known of its courtship behaviour. The only known nest was a shallow bowl in the top of a rotting tree stump that was lined with wood chips and dry leaves. The two young chicks were entirely covered in black down typical of precocial newly hatched rails. The estimated population of 3,500–15,000 birds and the restricted range mean that the invisible rail is classified as vulnerable by the International Union for Conservation of Nature (IUCN). Habitat loss has occurred through the harvesting of sago and conversion of the wetlands to rice cultivation, and the rail is eaten by local people. The described nest was in an area frequented by local villagers, so the rail may be more adaptable to habitat changes than had been thought.

Taxonomy

The rails are a large and very widespread family, with nearly 150 species. They are small to medium-sized, terrestrial or wetland birds, and their short bodies are often flattened laterally to help them move through dense vegetation. Island species readily become flightless; of 53 extant or recently extinct taxa restricted to islands, 32 have lost the ability to fly. [2]

The invisible rail, first classified by English zoologist George Robert Gray in 1860, is the only member of the monotypic genus Habroptila. [3] [1] The genus name Habroptila derives from the Greek habros, "delicate, pretty, splendid" and ptilon, "feather, wing"; [4] wallacii commemorates British zoologist Alfred Russel Wallace. [5] Local names include "soisa", "tibiales" and "rèie". [6]

This rail is related to the New Guinea flightless rail, Megacrex inepta, and the chestnut rail, Eulabeornis castaneoventris, all three Australasian genera probably being derived from Amaurornis ancestors. [1] [7] Storrs Olson argued that the genus Megacrex was so similar to Habroptila that Megacrex should be considered a junior synonym of Habroptila, resulting in two species in the genus. [8] This was further lumped in Sidney Dillon Ripley's 1977 monograph of the Rallidae; he included Habroptila within the large genus Rallus. This suggestion was not accepted by Gerlof Fokko Mees, who pointed out distinct differences in the shape and structure of the bill. [9] A 2012 molecular phylogenetic analysis based on mitochondrial DNA sequence similarity found that Habroptila is part of evolutionary radiation within the broad genus Gallirallus that took place around 400,000 years ago in the region. [10] A 2014 genetic study found that it formed a clade with the extinct Hawkins's rail of the Chatham Islands, New Zealand, the divergence was estimated to have taken place around 10 million years ago, this clade was in turn sister to Gallirallus. [11]

Description

Habroptila wallacii on a 2012 Indonesian stamp Habroptila wallacii 2012 Indonesia stamp.jpg
Habroptila wallacii on a 2012 Indonesian stamp

The invisible rail is a large, 33 to 40 cm (13–16 in) long, flightless bird. [1] The adult has a mainly dark slate-grey body, dark brown plumage on the lower back, rump and wings, and a black uppertail. Its underparts are slightly paler slate-grey than the back, and the bare skin around the eye, the long, thick bill and the strong legs are bright red. [12] It has a small spine at the bend of the wings. [3] The sexes are identical in appearance; the plumage of fledged immature birds has not been described. [12]

The invisible rail is superficially similar to the purple swamphen, Porphyrio porphyrio, which has recently been found in Halmahera, but that species is larger, with a short, thick red bill and a red forehead shield; it also has purple underparts and a white undertail. [12] The invisible rail is different from the Calayan rail, Gallirallus calayanensis, in that it is larger and lacks the barred plumage of that species; there is no overlap between the ranges of the two species. [13]

The call is a low drumming, accompanied by a tuk, tuk, tuk made with the wings. [12] The nature of the vocalisation led to a local legend that the sound is made by the bird beating on a hollow tree or branch with its feet. [6] Gerd Heinrich noted the local name "soisa", meaning drum, and described the call as being a subdued drumming purre – purre – purre – purre – purre which sometimes ends in a loud shrill scream. The bird also produced a dull hum similar to the voice of the banded pig (Sus scrofa vittatus) and reminiscent of the call of the snoring rail (Aramidopsis plateni). [14] Calling is most frequent in the early morning or late evening, and a human tapping a sago stem with a machete may elicit a response from the bird. [12] A quieter version of the call is given at the nest. [15] Other sounds attributed to this rail, such as loud screams, may be incorrect, since they are like those produced by the pale-vented bush-hen (Amaurornis moluccana). [12]

Distribution and habitat

The invisible rail inhabits the dense, spiky sago swamps of Halmahera, particularly where forest adjoins the boggy areas. Claims that the rail occurs in alang-alang grass are thought to have arisen from confusion with the pale-vented bush-hen. [12] German ornithologist Gerd Heinrich, who prepared for his Halmahera trip by rolling in stinging nettles, wrote of the sago swamp habitat in the 1930s: [16]

I am solidly confident no European has ever seen this rail alive, for that requires such a degree of toughening and such demands on oneself as I cannot so easily attribute to others. Habroptila is shielded by the awful thorns of the sago swamps... In this thorn wilderness, I walked barefoot and half-naked for weeks.

Sightings of the rail from 1950 to 2003 were from a restricted area of West Halmahera Regency, at the base of the western peninsula of the island, but it was recorded prior to 1950 as far as the southern point of Halmahera. [7] More recent records showed that it is still present in a significantly larger area, including the northeast of the island, [15] and locals claim that it also occurs in the swamps near Kao, in the northwest. [7]

Behaviour

Sago palms Sago (Metroxylon sagu) in New Guinea.jpg
Sago palms

The difficult habitat and retiring nature of the invisible rail mean that information on its lifestyle is sparse, and there are few confirmed sightings. [17] Recorded food items include sago shoots and insects. It also feeds at cut sago plants, although it is unclear whether it is eating the decaying plant or searching for other edible items. [7] It swallows small stones, as do all rails, to help break up its food in the gizzard. [18]

The invisible rail is thought to be monogamous, but little else is known of its courtship behaviour prior to nesting. A report of four or five striped chicks was long thought to be incorrect, since such a plumage is not normal for rails. [7] In this family, chicks are typically precocial, downy and black, with any ornamentation confined to the head, bare flesh, or specially modified plume feathers. [19]

The issue was resolved in November 2010 when a nest was found in the top of a rotting tree stump, 1 m (39 in) above ground level and 46 m (151 ft) in from the edge of a dry swamp forest in Aketajawe-Lolobata National Park. The nest depression was 15 cm (5.9 in) in depth, with a lower layer of small wood chips at its base and a lining of dead leaves. The egg shells were brownish-white with dark brown and black markings of different sizes. The two very young chicks were entirely covered in black down, contrasting with a white pollux (the equivalent of the thumbnail on a human hand) and pink index nail. The bill was black with a white tip, and the legs were black-streaked brown. The eyes had grey irises and blue pupils. Rail chicks leave the nest soon after hatching, so the chicks were assumed to be only a day or two old. [15]

Status

Bird species with a restricted range are especially vulnerable to human activities, and eight of the 26 bird species occurring only in the Northern Maluku Endemic Bird Area are threatened, including the invisible rail. [7] Almost a quarter of all rail species have conservation concerns, and flightless island species are particularly at risk, at least 15 species having become extinct since 1600. [20] The estimated population of the invisible rail is 3,500–15,000 birds, [17] and its restricted range and small population mean that the species is classified as vulnerable by the International Union for Conservation of Nature (IUCN), [1] although this rail is so poorly known that it may be more common than the estimates suggest. [7]

Habitat loss has occurred through commercial harvesting of the sago, [7] or conversion to rice cultivation and fishponds. [1] The rail is prized food for local people who catch it with traps made from strings of bark and hunt it with dogs. [12] The only described nest was in an area well-used by local villagers, and the rail may be more adaptable to habitat changes than had been thought. There were also several sightings in northeast Halmahera in 2008 and 2011, extending the area in which this bird has been seen in recent years. [15]

Related Research Articles

<span class="mw-page-title-main">Rail (bird)</span> Family of birds

Rails are a large, cosmopolitan family of small- to medium-sized terrestrial and/or semi-amphibious birds. The family exhibits considerable diversity in its forms, and includes such ubiquitous species as the crakes, coots, and gallinule; other rail species are extremely rare or endangered. Many are associated with wetland habitats, some being semi-aquatic like waterfowl, but many more are wading birds or shorebirds. The ideal rail habitats are marsh areas, including rice paddies, and flooded fields or open forest. They are especially fond of dense vegetation for nesting. The rail family is found in every terrestrial habitat with the exception of dry desert, polar or freezing regions, and alpine areas. Members of Rallidae occur on every continent except Antarctica. Numerous unique island species are known.

<span class="mw-page-title-main">Water rail</span> Species of bird

The water rail is a bird of the rail family which breeds in well-vegetated wetlands across Europe, Asia and North Africa. Northern and eastern populations are migratory, but this species is a permanent resident in the warmer parts of its breeding range. The adult is 23–28 cm (9–11 in) long, and, like other rails, has a body that is flattened laterally, allowing it easier passage through the reed beds it inhabits. It has mainly brown upperparts and blue-grey underparts, black barring on the flanks, long toes, a short tail and a long reddish bill. Immature birds are generally similar in appearance to the adults, but the blue-grey in the plumage is replaced by buff. The downy chicks are black, as with all rails. The former subspecies R. indicus, has distinctive markings and a call that is very different from the pig-like squeal of the western races, and is now usually split as a separate species, the brown-cheeked rail.

<span class="mw-page-title-main">Inaccessible Island rail</span> Small flightless bird in the family Rallidae endemic to an island in the Tristan Archipelago

The Inaccessible Island rail is a small bird of the rail family, Rallidae. Endemic to Inaccessible Island in the Tristan Archipelago in the isolated south Atlantic, it is the smallest extant flightless bird in the world. The species was described by physician Percy Lowe in 1923 but had first come to the attention of scientists 50 years earlier. The Inaccessible Island rail's affinities and origin were a long-standing mystery; in 2018 its closest relative was identified as the South American dot-winged crake, and it was proposed that both species should be nested within the genus Laterallus.

<span class="mw-page-title-main">Watercock</span> Species of bird

The watercock is a waterbird in the rail and crake family, Rallidae that is widely distributed across Southeast Asia. It is the only member of the genus Gallicrex.

The Calayan rail is a flightless bird of the rail, moorhen, and coot family (Rallidae) that inhabits Calayan Island in the Philippines. It is the only member of the genus Aptenorallus. Though well known to natives of the island as the "piding", it was first observed by ornithologist Carmela Española in May 2004 and the discovery was officially announced on August 16, 2004. The formal description as a species new to science appeared in the journal Forktail.

<span class="mw-page-title-main">Laysan rail</span> Extinct species of bird

The Laysan rail or Laysan crake was a flightless bird endemic to the Northwest Hawaiian Island of Laysan. This small island was and still is an important seabird colony, and sustained a number of endemic species, including the rail. It became extinct due to habitat loss by domestic rabbits, and ultimately World War II.

<span class="mw-page-title-main">Halmahera paradise-crow</span> Species of bird

The Halmahera paradise-crow also known as the silky crow, is a medium-sized crow-like bird-of-paradise.

<span class="mw-page-title-main">Rodrigues rail</span> Extinct bird of the rail family that was endemic to Rodrigues

The Rodrigues rail, also known as Leguat's gelinote or Leguat's rail, is an extinct species of the rail family that was endemic to the Mascarene island of Rodrigues. The bird was first documented from life by two accounts from 1691–93 and 1725–26. Subfossil remains were later discovered and correlated with the old accounts in 1874, and the species was named E. leguati in Leguat's honour. It is generally kept in its own genus, Erythromachus, but has sometimes been assigned to the genus Aphanapteryx along with its close relative the red rail of Mauritius; their relationship with other rails is unclear.

<i>Gallirallus</i> Genus of birds

Gallirallus is a genus of rails that live in the Australasian-Pacific region. The genus is characterised by an ability to colonise relatively small and isolated islands and thereafter to evolve flightless forms, many of which became extinct following Polynesian settlement.

<span class="mw-page-title-main">Réunion swamphen</span> Hypothetical extinct species of bird

The Réunion swamphen, also known as the Réunion gallinule or oiseau bleu, is a hypothetical extinct species of rail that was endemic to the Mascarene island of Réunion. While only known from 17th- and 18th-century accounts by visitors to the island, it was scientifically named in 1848, based on the 1674 account by Sieur Dubois. A considerable literature was subsequently devoted to its possible affinities, with current researchers agreeing it was derived from the swamphen genus Porphyrio. It has been considered mysterious and enigmatic due to the lack of any physical evidence of its existence.

<span class="mw-page-title-main">Tahiti rail</span> Extinct species of bird from Tahiti

The Tahiti rail, Tahitian red-billed rail, or Pacific red-billed rail is an extinct species of rail that lived on Tahiti. It was first recorded during James Cook's second voyage around the world (1772–1775), on which it was illustrated by Georg Forster and described by Johann Reinhold Forster. No specimens have been preserved. As well as the documentation by the Forsters, there have been claims that the bird also existed on the nearby island of Mehetia. The Tahiti rail appears to have been closely related to, and perhaps derived from, the buff-banded rail, and has also been historically confused with the Tongan subspecies of that bird.

<span class="mw-page-title-main">Hawkins's rail</span> Extinct species of bird

Hawkins's rail, also called the giant Chatham Island rail or in Moriori as mehonui, is an extinct species of flightless rail. It was endemic to the Chatham Islands east of New Zealand. It is known to have existed only on the main islands of Chatham Island and Pitt Island. Hawkins's rail was the largest terrestrial bird native to the Chatham Islands, around 40 centimetres (16 in) tall and weighing about 2 kilograms (4.4 lb). It had a long, downward curving beak. Historic accounts likely referring to the bird by the name "mehonui" suggest that it was red-brown in colour, and it has been compared to the weka in ecological habits, using its beak to probe decaying wood for invertebrates. Hawkins's rail likely became extinct due to overhunting by the islands native inhabitants, the Moriori, and the bird is known from skeletal remains found in their kitchen middens.

<span class="mw-page-title-main">Buff-banded rail</span> Species of bird

The buff-banded rail is a distinctively coloured, highly dispersive, medium-sized rail of the rail family, Rallidae. This species comprises several subspecies found throughout much of Australasia and the south-west Pacific region, including the Philippines, New Guinea, Australia, New Zealand, and numerous smaller islands, covering a range of latitudes from the tropics to the Subantarctic.

<i>Porzana</i> Genus of birds

Porzana is a genus of birds in the crake and rail family, Rallidae. Its scientific name is derived from Venetian terms for small rails. The spotted crake is the type species.

<span class="mw-page-title-main">Zapata rail</span> Species of bird of the monotypic genus Cyanolimnas

The Zapata rail is a medium-sized, dark-coloured rail. It has brown upperparts, greyish-blue underparts, a red-based yellow bill, white undertail coverts, and red eyes and legs. Its short wings render it almost flightless. It is endemic to the wetlands of the Zapata Peninsula in southern Cuba, where its only known nest was found in sawgrass tussocks. Little is known of its diet or reproductive behaviour, and its described calls may belong to a different species.

<span class="mw-page-title-main">Snoring rail</span> Species of bird

The snoring rail, also known as the Celebes rail or Platen's rail, is a large flightless rail and the only member of the genus Aramidopsis. The species is endemic to Indonesia, and it is found exclusively in dense vegetation in wet areas of Sulawesi and nearby Buton. The rail has grey underparts, a white chin, brown wings and a rufous patch on the hind-neck. The sexes are similar, but the female has a brighter neck patch and a differently coloured bill and iris. The typical call is the snoring: ee-orrrr sound that gives the bird its English name.

<span class="mw-page-title-main">Chatham rail</span> Extinct species of bird

The Chatham rail is an extinct flightless species of bird in the family Rallidae. It was endemic to Chatham, Mangere and Pitt Islands, in the Chatham archipelago of New Zealand. The Chatham rail was first discovered on Mangere in 1871, and 26 specimens collected there are known from museum collections. Its Māori name was "mātirakahu".

<span class="mw-page-title-main">Okinawa rail</span> Species of bird

The Okinawa rail is a species of bird in the rail family, Rallidae. It is endemic to Okinawa Island in Japan where it is known as the Yanbaru kuina. Its existence was only confirmed in 1978 and it was formally described in 1981 although unidentified rails had been recorded on the island since at least 1973 and local stories of a bird known as the agachi kumira may refer to this species.

<span class="mw-page-title-main">New Guinea flightless rail</span> Species of bird

The New Guinea flightless rail, also known as the Papuan flightless rail, is a species of bird in the family Rallidae, in the monotypic genus Megacrex. Sometimes however, it was included in Amaurornis or Habroptila, but this is incorrect.

The Mangaia rail is an extinct species of flightless bird in the rail family, Rallidae.

References

  1. 1 2 3 4 5 6 "Habroptila wallacii". IUCN Red List of Threatened Species . BirdLife International. 2016: e.T22692781A93369321. 2016. doi: 10.2305/IUCN.UK.2016-3.RLTS.T22692781A93369321.en . Retrieved 19 November 2021.
  2. ↑ del Hoyo, Josep; Elliott, Andrew; Sargatal, Jordi; Christie, David A.; de Juana, Eduardo, eds. (2013). "Rails, Gallinules and Coots" . Handbook of the Birds of the World Alive. Barcelona: Lynx Edicions. doi:10.2173/bow.rallid1.01. S2CID   216475559 . Retrieved 13 April 2014.
  3. 1 2 Gray, George Robert (1860). "List of birds collected by Mr. Wallace at the Moluccia Islands, with the descriptions of new species, etc". Proceedings of the Zoological Society of London (Part 28): 341–366 [365]. The title page is dated 1860 but the article was not published until the following year. See: Dickinson, Edward C. (2005). "The Proceedings of the Zoological Society of London, 1859–1900: an exploration of breaks between calendar years of publication". Journal of Zoology. 266 (4): 427–430. doi:10.1017/S0952836905007077.
  4. ↑ ἁβρός, πτίλον . Liddell, Henry George ; Scott, Robert ; A Greek–English Lexicon at the Perseus Project.
  5. ↑ Jobling, James A. (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. pp.  184, 406. ISBN   978-1-4081-2501-4.
  6. 1 2 de Haan, G A L (1950). "Notes on the Invisible Flightless Rail of Halmahera (Habroptila wallacii Gray)". Amsterdam Naturalist. 1: 57–60.
  7. 1 2 3 4 5 6 7 8 "Invisible Rail Habroptila wallacii" (PDF). Birdbase. Hokkaido Institute of Environmental Sciences. Archived from the original (PDF) on 2 October 2011. Retrieved 17 June 2011.
  8. ↑ Olson, Storrs L (1973). "A classification of the Rallidae" (PDF). Wilson. 85 (4): 381–416.
  9. ↑ Mees, G F (1982). "Birds from the lowlands of southern New Guinea (Merauke and Koembe)". Zoologische Verhandelingen. 191: 1–188.
  10. ↑ Kirchman, Jeremy J (2012). "Speciation of Flightless Rails on Islands: A DNA-based phylogeny of the typical rails of the Pacific". The Auk. 129 (1): 56–69. doi: 10.1525/auk.2011.11096 . S2CID   85940913.
  11. ↑ Garcia-R, Juan C.; Gibb, Gillian C.; Trewick, Steve A. (December 2014). "Deep global evolutionary radiation in birds: Diversification and trait evolution in the cosmopolitan bird family Rallidae". Molecular Phylogenetics and Evolution. 81: 96–108. doi:10.1016/j.ympev.2014.09.008. ISSN   1055-7903. PMID   25255711.
  12. 1 2 3 4 5 6 7 8 Taylor (1998) pp. 451–452.
  13. ↑ Allen, Desmond; Oliveros, Carl; Española, Carmela; Broad, Genevieve; Gonzalez, Juan Carlos T (2004). "A new species of Gallirallus from Calayan island, Philippines" (PDF). Forktail. 20: 1–7. Archived from the original (PDF) on 18 August 2011. Retrieved 18 June 2011.
  14. ↑ Heinrich, Gerd (1956). "Biologische Aufzeichnungen über Vögel von Halmahera und Batjan". Journal für Ornithologie (in German). 97 (1): 31–40. doi:10.1007/BF01670833. S2CID   40396589.
  15. 1 2 3 4 Bashari, Hanom; van Balen, Bas (2011). "First breeding record of the Invisible Rail Habroptila wallacii". BirdingASIA. 15: 20–22.
  16. ↑ Collar, Nigel J (2009). "Pioneer of Asian ornithology: Gerd Heinrich" (PDF). BirdingASIA. 11: 33–40.
  17. 1 2 "Invisible Rail Habroptila wallacii". Species factsheet. BirdLife International. Retrieved 16 June 2011.
  18. ↑ Taylor (1998) p. 39.
  19. ↑ Krebs, Elizabeth A; Putland, David A (2004). "Chic chicks: the evolution of chick ornamentation in rails". Behavioral Ecology . 15 (6): 946–951. doi: 10.1093/beheco/arh078 .
  20. ↑ Taylor (1998) pp. 56–61.

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