The Okinawa rail (''Hypotaenidia okinawae'') is a species of

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

in the rail family,

Rallidae The rails, or Rallidae, are a large cosmopolitan family of small- to medium-sized, ground-living birds. The family exhibits considerable diversity and includes the crakes, coots, and gallinules. Many species are associated with wetlands, althou ...

. It is

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 else ...

to Okinawa Island in Japan where it is known as the . 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.Brazil, Mark A. (1991) ''The Birds of Japan'', Christopher Helm, London. It is a medium-sized and almost

flightless Flightless birds are birds that through evolution lost the ability to fly. There are over 60 extant species, including the well known ratites (ostriches, emu, cassowaries, rheas, and kiwi) and penguins. The smallest flightless bird is the ...

rail with short wings and tail, olive-brown upperparts, black underparts with white bars and a red

bill Bill(s) may refer to: Common meanings * Banknote, paper cash (especially in the United States) * Bill (law), a proposed law put before a legislature * Invoice, commercial document issued by a seller to a buyer * Bill, a bird or animal's beak Plac ...

and legs. It occurs in subtropical moist

forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...

s and in neighboring

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s. It nests and feeds on the ground but usually roosts in trees. It is classified as an endangered species and is threatened by

habitat loss Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

and introduced

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

Taxonomy

The species was first described in 1981 by

Yoshimaro Yamashina Marquis was a Japanese ornithologist. He was the founder of the Yamashina Institute for Ornithology. Biography Yamashina was born in Kōjimachi, Tokyo, the second son of Prince Kikumaro Yamashina and Princess Noriko (Kujo) Yamashina. Throug ...

and T. Mano in the ''Journal of the Yamashina Institute of Ornithology''.Peterson, Alan P. (2002)
Zoonomen Nomenclatural data
'. Downloaded on 22 October 2008. This was based on a specimen found dead on June 2 at Mt. Fuenchiji in

Kunigami District, Okinawa is a district located in Okinawa Prefecture, Japan. Roughly translated, kunigami means "head of the country", referring to its northern location on the island of Okinawa. Compare this to Shimajiri District, Okinawa. As of 2020, the district h ...

.Taylor, Barry & Ber van Perlo (1998) ''Rails: A Guide to the Rails, Crakes, Gallinules and Coots of the World'', Pica Press, Sussex. It was initially placed in the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

Rallus ''Rallus'' is a genus of wetland birds of the rail family. Sometimes, the genera ''Lewinia'' and ''Gallirallus'' are included in it. Six of the species are found in the Americas, and the three species found in Eurasia, Africa and Madagascar ar ...

'' but then moved to ''

Gallirallus ''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 ...

'', a genus of medium-sized, often flightless, rails found in

Australasia Australasia is a region that comprises Australia, New Zealand and some neighbouring islands in the Pacific Ocean. The term is used in a number of different contexts, including geopolitically, physiogeographically, philologically, and ecologi ...

and

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

. It is closely related to the

barred rail The barred rail (''Hypotaenidia torquata'') is a species of rail found across the Philippines, Sulawesi (Indonesia) and Salawati Salawati is one of the four major islands in the Raja Ampat Islands in Southwest Papua (formerly West Papua), ...

(''G. torquatus'') and New Britain rail (''G. insignis'') as well as to the

Calayan rail The Calayan rail (''Aptenorallus calayanensis'') 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 nat ...

(''G. calayanensis''), another recently discovered species.BirdLife International (2004)
Remarkable rail discovered "just in time"
'. Downloaded on 22 October 2008.

Description

It is about 30 cm long with a wingspan of 50 cm and a weight of around 435 g. It is almost flightless and has very short wings and tail. The bill is large and bright red with a whitish tip. The long, strong legs are red as are the

iris Iris most often refers to: *Iris (anatomy), part of the eye *Iris (mythology), a Greek goddess * ''Iris'' (plant), a genus of flowering plants * Iris (color), an ambiguous color term Iris or IRIS may also refer to: Arts and media Fictional ent ...

and eye-ring. The upperparts are olive-brown while the underparts are black with narrow white bars. The face is black with a white spot between the bill and eye and a white line behind the eye, extending back to the side of the neck. The undertail-coverts are dark brown with pale bars. Juvenile birds are paler than the adults and are mottled white below rather than barred. The spot in front of the eye is tinged with brown while the stripe behind is shorter than in the adult. The bill and iris are brownish and the legs and feet are yellow-ochre. It is a noisy bird with a variety of loud calls. It calls most often early and late in the day, usually from the ground but sometimes from trees. Pairs often call together and up to 12 birds have been heard in one area.

Distribution and habitat

It is found only in

Yanbaru is the Okinawan and Kunigami name given to the forested northern part of Okinawa Island in Japan. Spanning the northern villages of Higashi, Kunigami, and Ōgimi, Yambaru contains some of the last large surviving tracts of subtropical rai ...

, the northern part of Okinawa Island in the

Ryukyu Islands The , also known as the or the , are a chain of Japanese islands that stretch southwest from Kyushu to Taiwan: the Ōsumi, Tokara, Amami, Okinawa, and Sakishima Islands (further divided into the Miyako and Yaeyama Islands), with Yona ...

of southern Japan, from where it gets its Japanese name. It has a total range of just 260 km². It occurs from sea-level to the highest mountains at 498 m above sea-level. In winter, some birds move lower down or move a little further south of the breeding range. It mainly occurs in

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, whic ...

broad-leaved A broad-leaved, broad-leaf, or broadleaf tree is any tree within the diverse botanical group of angiosperms that has flat leaves and produces seeds inside of fruits. It is one of two general types of trees, the other being a conifer, a tree with ne ...

forest but also occurs in marshes, grassland and cultivated land close to forested areas and water. Itaji (''

Castanopsis sieboldii ''Castanopsis sieboldii'', also known as the Itajii chinkapin or Itajii, is a species of evergreen tree that lives in subtropical eastern Asia. This is a climax species that is commonly found in the Japanese temperate rainforest. Specimens are al ...

'') is the dominant tree in the rail's habitat but it also occurs among other trees such as Ryukyu Pine (''

Pinus luchuensis ''Pinus luchuensis'', commonly called Luchu pine or Okinawa pine, is a species of conifer in the family Pinaceae endemic to, and locally abundant in the Ryukyu Islands of Japan. It was once threatened by habitat loss in the wild, where it can ...

''). It requires dense ground vegetation as well as standing water for bathing.

Behavior

It is a poor flyer but it can run rapidly. It spends most of its time on the ground but usually roosts in trees, climbing up to sleep on a branch or sloping trunk. In the morning, it preens and stretches before dropping straight to the ground. It is usually found in dense cover but comes into the open to bathe. It bathes for short bouts of 2–4 minutes before preening for 4–20 minutes. It feeds on lizards, amphibians,

snail A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class G ...

s and large insects such as

locust Locusts (derived from the Vulgar Latin ''locusta'', meaning grasshopper) are various species of short-horned grasshoppers in the family Acrididae that have a swarming phase. These insects are usually solitary, but under certain circumstanc ...

s. Food is mainly taken from the forest floor but may also be taken from shallow water. Pairs are monogamous and appear to mate for life. The

nest A nest is a structure built for certain animals to hold eggs or young. Although nests are most closely associated with birds, members of all classes of vertebrates and some invertebrates construct nests. They may be composed of organic materi ...

is built on the ground and made of leaves, grass and fern fronds. The

eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

are laid between May and July and there are 2–4 in a clutch. The eggs are oval in shape and white with reddish, pinkish or brownish markings concentrated at the larger end. The downy young are black with yellowish legs and feet and a white bill with a blackish base and tip. The eggs and young are often predated by the habu (''

Trimeresurus flavoviridis ''Protobothrops flavoviridis'' is a species of venomous pit viper endemic to the Ryukyu Islands of Japan. No subspecies are currently recognized. Local common names include habu,Gumprecht A, Tillack F, , Captain A, Ryabov S. 2004. ''Asian Pitvip ...

''), a venomous snake.

Status and conservation

The species is classified as

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and in ...

by BirdLife International because of its small, declining population and restricted range. The total population was estimated at 1,800 birds in 1986. Surveys between 1996 and 2004 suggested a significant decline to about 720 birds and a northward contraction of the range of about 40%. However, a survey in 2006 found no further range contraction.BirdLife International (2008
Species factsheet: ''Gallirallus okinawae''
Downloaded on 15 October 2008. It is threatened by the loss and fragmentation of its forest habitat due to logging,

agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people t ...

and the building of roads, dams and

golf course A golf course is the grounds on which the sport of golf is played. It consists of a series of holes, each consisting of a tee box, a fairway, the rough and other hazards, and a green with a cylindrical hole in the ground, known as a "cup". ...

s. Introduced predators such as cats, dogs and the

small Asian mongoose Small Asian mongoose is a common name applied to two mammals which were formerly considered to be a single species: * Javan mongoose *Small Indian mongoose The small Indian mongoose (''Urva auropunctata'') is a mongoose species native to Iraq an ...

probably have an impact while some birds are killed by vehicles on roads. The species is legally protected in Japan and has been declared a "

Natural Monument A natural monument is a natural or natural/cultural feature of outstanding or unique value because of its inherent rarity, representative of aesthetic qualities or cultural significance. Under World Commission on Protected Areas guidelines, na ...

" and a "Special Bird for Protection".

became a national park in 2016 and several forest sites have been bought by conservation organizations as

nature reserve A nature reserve (also known as a wildlife refuge, wildlife sanctuary, biosphere reserve or bioreserve, natural or nature preserve, or nature conservation area) is a protected area of importance for flora, fauna, or features of geological or ...

s. Trapping is taking place to reduce predator numbers and traffic calming has been introduced to some areas to reduce the number of birds killed on roads. A captive breeding program is planned for the future. The Japanese Ministry of the Environment has laid out a 10-year action plan with steps it plans to take to stabilize the species numbers.

References

External links

BirdLife Species Factsheet.Oriental Bird Images: Okinawa rail
{{Authority control Hypotaenidia Birds of the Ryukyu Islands Natural monuments of Japan Birds described in 1981 Endemic fauna of the Ryukyu Islands Endemic birds of Japan Taxonomy articles created by Polbot