Okinawa Rail
Encyclopedia
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 . 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.
It is a medium-sized and almost flightless
rail with short wings and tail, olive-brown upperparts, black underparts with white bars and a red bill
and legs.
It occurs in subtropical moist forest
s and in neighbouring habitat
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 and introduced
predators.
and T. Mano in the Journal of the Yamashina Institute of Ornithology. This was based on a specimen found dead on June 2 at Mt. Fuenchiji in Kunigami District, Okinawa
. It was initially placed in the genus
Rallus
but then moved to Gallirallus
, a genus of medium-sized, often flightless, rails found in Australasia
and Asia
. It is closely related to the Barred Rail
(G. torquatus) and New Britain Rail
(G. insignis) as well as to the Calayan Rail
(G. calayanensis), another recently discovered species.
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.
of southern Japan. 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
broad-leaved forest but also occurs in marshes, grassland and cultivated land close to forested areas and water. Itaji (Castanopsis sieboldii) is the dominant tree in the rail's habitat but it also occurs among other trees such as Ryukyu Pine (Pinus luchuensis
). It requires dense ground vegetation as well as standing water for bathing.
It feeds on lizard
s, amphibian
s, snail
s and large insects such as locust
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
is built on the ground and made of leaves, grass and fern fronds. The eggs
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
), a venomous snake.
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.
It is threatened by the loss and fragmentation of its forest habitat due to logging
, agriculture and the building of roads, dams and golf courses. Introduced
predators such as cats, dogs and the Small Asian Mongoose 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
" and a "Special Bird for Protection". Yambaru became a national park
in 1996 and several forest sites have been bought by conservation organizations as nature reserve
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
programme is planned for the future.
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
in the rail family, Rallidae
Rallidae
The rails, or Rallidae, are a large cosmopolitan family of small to medium-sized birds. The family exhibits considerable diversity and the family also includes the crakes, coots, and gallinules...
. It is endemic to Okinawa Island
Okinawa Island
Okinawa Island is the largest of the Okinawa Islands and the Ryukyu Islands of Japan, and is home to Naha, the capital of Okinawa Prefecture. The island has an area of...
in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
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.
It is a medium-sized and almost flightless
Flightless bird
Flightless birds are birds which lack the ability to fly, relying instead on their ability to run or swim. They are thought to have evolved from flying ancestors. There are about forty species in existence today, the best known being the ostrich, emu, cassowary, rhea, kiwi, and penguin...
rail with short wings and tail, olive-brown upperparts, black underparts with white bars and a red bill
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
and legs.
It occurs in subtropical moist forest
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...
s and in neighbouring habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
s. It nests and feeds on the ground but usually roosts in trees. It is classified as an endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
and is threatened by habitat loss and introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
predators.
Taxonomy
The species was first described in 1981 by Yoshimaro YamashinaYoshimaro 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. He developed a love of birds at an early age, which were found in abundance on the vast Yamashina...
and T. Mano in the Journal of the Yamashina Institute of Ornithology. This was based on a specimen found dead on June 2 at Mt. Fuenchiji in Kunigami District, Okinawa
Kunigami District, Okinawa
is a district located in Okinawa, 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....
. It was initially placed in the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Rallus
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 are very closely related to each other, suggesting they are descended...
but then moved to Gallirallus
Gallirallus
Gallirallus is a genus that contains about a dozen living species of rails that live in the Australasian-Pacific region. Many of these, including the most well-known one - the bold and inquisitive weka of New Zealand - are flightless or nearly so; others, such as the Buff-banded Rail, can go for...
, a genus of medium-sized, often flightless, rails found in Australasia
Australasia
Australasia is a region of Oceania comprising Australia, New Zealand, the island of New Guinea, and neighbouring islands in the Pacific Ocean. The term was coined by Charles de Brosses in Histoire des navigations aux terres australes...
and Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
. It is closely related to the Barred Rail
Barred Rail
The Barred Rail is a species of bird in the Rallidae family.It is found in Indonesia and the Philippines.-References:* BirdLife International 2008. . Downloaded on 4 November 2008....
(G. torquatus) and New Britain Rail
New Britain Rail
The Pink-legged Rail , also known as the New Britain Rail, is a species of bird in the Rallidae family.-Distribution and habitat:...
(G. insignis) as well as to the Calayan Rail
Calayan Rail
The Calayan Rail is a flightless bird of the rail, moorhen, and coot family that inhabits Calayan Island in the Philippines. 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 officially announced on...
(G. calayanensis), another recently discovered species.
Description
It is about 30 cm long with a wingspan of 50 cm and a weight of around 433-434.5 grams. 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 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
Juvenile (organism)
A juvenile is an individual organism that has not yet reached its adult form, sexual maturity or size. Juveniles sometimes look very different from the adult form, particularly in terms of their colour...
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 Yambaru, the northern part of Okinawa Island in the Ryukyu IslandsRyukyu Islands
The , also known as the , is a chain of islands in the western Pacific, on the eastern limit of the East China Sea and to the southwest of the island of Kyushu in Japan. From about 1829 until the mid 20th century, they were alternately called Luchu, Loochoo, or Lewchew, akin to the Mandarin...
of southern Japan. 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
Evergreen
In botany, an evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season.There are many different kinds of evergreen plants, both trees and shrubs...
broad-leaved forest but also occurs in marshes, grassland and cultivated land close to forested areas and water. Itaji (Castanopsis sieboldii) is the dominant tree in the rail's habitat but it also occurs among other trees such as Ryukyu Pine (Pinus luchuensis
Pinus luchuensis
Luchu Pine is a species of conifer in the Pinaceae family.It is found only in Japan Okinawa.It is threatened by habitat loss.-References:* Conifer Specialist Group 2000. . Downloaded on 10 July 2007....
). It requires dense ground vegetation as well as standing water for bathing.
Behaviour
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 lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
s, amphibian
Amphibian
Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...
s, snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
s and large insects such as locust
Locust
Locusts are the swarming phase of short-horned grasshoppers of the family Acrididae. These are species that can breed rapidly under suitable conditions and subsequently become gregarious and migratory...
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
Bird nest
A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American Robin or Eurasian Blackbird, or the elaborately woven hanging nest of the...
is built on the ground and made of leaves, grass and fern fronds. The eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
are laid between May and July and there are 2-4 in a clutch
Clutch (eggs)
A clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...
. 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
Trimeresurus flavoviridis
Trimeresurus flavoviridis is a venomous pitviper species found in Japan in the Ryukyu Islands. No subspecies are currently recognized.-Description:...
), a venomous snake.
Status and conservation
The species is classified as EndangeredEndangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
by BirdLife International
BirdLife International
BirdLife International is a global Partnership of conservation organisations that strives to conserve birds, their habitats and global biodiversity, working with people towards sustainability in the use of natural resources...
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.
It is threatened by the loss and fragmentation of its forest habitat due to logging
Logging
Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...
, agriculture and the building of roads, dams and golf courses. Introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
predators such as cats, dogs and the Small Asian Mongoose 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
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....
" and a "Special Bird for Protection". Yambaru became a national park
National park
A national park is a reserve of natural, semi-natural, or developed land that a sovereign state declares or owns. Although individual nations designate their own national parks differently A national park is a reserve of natural, semi-natural, or developed land that a sovereign state declares or...
in 1996 and several forest sites have been bought by conservation organizations as nature reserve
Nature reserve
A nature reserve is a protected area of importance for wildlife, flora, fauna or features of geological or other special interest, which is reserved and managed for conservation and to provide special opportunities for study or research...
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
Captive breeding
Captive breedingis the process of breeding animals in human controlled environments with restricted settings, such as wildlife reserves, zoos and other conservation facilities; sometimes the process is construed to include release of individual organisms to the wild, when there is sufficient...
programme is planned for the future.