Species information
Scientific name: Gallirallus okinawae
Japanese name: ヤンバルクイナ
Chinese name: 沖繩秧雞、山原秧雞
English name: Okinawa rail
Origin: Northern Okinawajima (endemic)
Ecology and description
1. Appearance
The Okinawa rail has a total length of approximately 35 cm and weighs about 450 g. The plumage from the crown to the tail is deep olive-green, the face is black, and a white line runs from behind the eye to the neck. The legs and bill are bright red, and the underbelly features a black-and-white barred pattern. There is no significant difference in appearance between males and females.
The Okinawa rail was described as a new species in 1981. Before that, locals called it “Agachaa,” meaning the flustered bird, or “Yamadui,” meaning the bird of the mountains. The Japanese common name, Yambaru Kuina, emphasizes that it is endemic to the Yambaru region.
The Okinawa rail is the official bird of Kunigami Village. It is designated as a National Natural Monument (Law for the Protection of Cultural Properties), a Nationally Endangered Species of Wild Fauna and Flora (Act on Conservation of Endangered Species of Wild Fauna and Flora), and is an endangered species.
2. Habits
The Okinawa rail is primarily diurnal, searching for food in the forest or bathing by the water during the day. At night, it sleeps in trees to avoid predators such as the Habu viper. It has sturdy legs and powerful claws that allow it to grip bark and walk up into trees. Consequently, giant trees with deeply fissured bark, such as Ryukyu Pine (Pinus luchuensis) or Castanopsis sieboldii, are its favorite sleeping spots.
The species is omnivorous, feeding on earthworms, lizards, acorns, snails, and various plant seeds. If you find large snail shells broken in the middle in the forest, those are traces of the Okinawa rail feeding. They have favorite “snail-hammering stones”; research shows that an individual rail will repeatedly bring snails to the same stone to crack them, leaving scattered shells nearby.
Okinawa rails nest on the ground and breed from late March to June. They lay 3 to 5 eggs per clutch, which hatch after about three weeks. Newly hatched chicks are entirely black. Both parents share the brooding duties. After about two months, the chicks develop the same coloration as adults and become independent.
3. Evolution
Close relatives of the Okinawa rail are distributed across various Pacific islands. This suggests that the ancestor of the Okinawa rail was likely a flighted rail species that dispersed to different islands. In the absence of terrestrial mammalian predators on small islands, they evolved into flightless forms. The flightless rails found on various islands are likely results of multiple independent events of convergent evolution.
The skeletal specimen displayed at the Yambaru Wildlife Conservation Center shows that, unlike typical birds, the Okinawa rail lacks a well-developed sternum and keel. The sternum is where breast muscles attach, and the ridge-like projection in the middle is called the keel, which supports the large muscles required for flight. In birds that fly long distances, such as pigeons, the keel is highly developed. However, observing the Okinawa rail skeleton reveals a small sternum, a non-protruding keel, wings that are small relative to the body, and very long legs. This structure demonstrates its adaptation to a flightless life, walking on the ground and climbing into trees.
Although the Okinawa rail is now found only in northern Okinawajima, fossils of the Okinawa rail have been found in strata about 20,000 years old in the Minatogawa Fissure in Yaese Town, southern Okinawajima. Researchers who compared the bones concluded that they are morphologically identical to the skeletons of the living Okinawa rail, not those of an ancestor or another species, which indicates that Okinawa rails were breeding across the whole island at that time. The extinction of the species in central and southern Okinawa today is likely due to the development of human habitats, which led to a massive decline in their population.
Where did the Okinawa rail come from?
Among the endemic species of the Central Ryukyus, many are “relict species” that were once widespread on the continent and survived only on the islands, such as the Ryukyu long-furred rat and the Amami rabbit. The Okinawa rail has a different origin: it is a species that dispersed to Okinawajima from the south.
According to DNA-based phylogenetic studies, the flighted ancestors of these rails probably set out from around the Philippines and eastern Indonesia and flew, wave after wave, to the islands of the Pacific during the Pleistocene, when sea levels repeatedly rose and fell. Many of the islands had no carnivorous mammalian predators, so flight was no longer essential for survival, and on each island the ancestral rails independently evolved into flightless forms.
Okinawajima originally had no native carnivorans (carnivorous mammals) either, and Japan’s Ministry of the Environment considers that the ancestor of the Okinawa rail came to Okinawajima from the south. How long ago this happened is not settled: the Ministry’s material says tens of thousands of years ago, while the DNA study estimates that the whole group of Pacific rails appeared much earlier (about 840,000 to 1.4 million years ago), and its author notes that these age estimates are uncertain.
After humans arrived on these islands one after another from the late Pleistocene to the Holocene, flightless rails were easy to catch, and together with predation by dogs, pigs and rats brought by humans, most of them went extinct. The map below shows the numbers of extant and extinct species on each island, and the table summarizes the extant species. Of the 11 extant species shown in the paper’s figure, 7 are listed by the IUCN as Vulnerable or worse, and the Okinawa rail is one of them.
References (explanation and map)
- Kirchman, J. 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. https://doi.org/10.1525/auk.2011.11096
- Ministry of the Environment, Japan: Conservation and Propagation Plan for the Okinawa Rail (in Japanese)
- Ministry of the Environment, Japan: Amami-Oshima Island, Tokunoshima Island, Northern part of Okinawa Island, and Iriomote Island (explanation of relict and newly evolved endemics)
- Natural Earth (base map, public domain)
- For the distribution of each extant species, see “References (table)” inside the “Extant flightless rails” section below.
Extant flightless rails (click to open the table and references)
| Scientific name (English name) | Distribution | Carnivorans (order Carnivora) | Current population | IUCN status |
|---|---|---|---|---|
| Gallirallus okinawae Okinawa rail | Northern Okinawajima (Yambaru) | Native: none Introduced: small Indian mongoose, cats, dogs | About 1,345 individuals (2023, Ministry of the Environment) | Endangered EN (Japan’s Ministry of the Environment: Critically Endangered CR) |
| Gallirallus calayanensis Calayan rail | Calayan Island, Philippines (Babuyan Islands) | Introduced: cats, dogs | 2,500–4,300 mature individuals | Vulnerable VU |
| Gallirallus owstoni Guam rail | Originally endemic to Guam; wild populations now on Rota and Cocos Island (reintroduced) | About 200 on Rota, about 60–80 on Cocos Island (2019) | Critically Endangered CR (uplisted in 2019 from Extinct in the Wild) | |
| Gallirallus wallacii invisible rail | Sago swamps of Halmahera | Introduced: dogs (occasionally catch rails) | 2,500–9,999 mature individuals | Vulnerable VU |
| Aramidopsis plateni snoring rail | Lowland to hill forests of Sulawesi (including Buton) | Native: present (e.g., Sulawesi palm civet) Introduced: cats, dogs | Vulnerable VU | |
| Megacrex inepta New Guinea flightless rail | Lowlands of New Guinea (north coast and southeast) | Native: none Brought by humans: dogs, cats | Least Concern LC | |
| Gallirallus insignis pink-legged rail | New Britain | About 1,500–7,000 mature individuals | Near Threatened NT | |
| Gallirallus woodfordi Woodford’s rail | Guadalcanal and Santa Isabel, Solomon Islands | Native: none | Least Concern LC | |
| Gallirallus rovianae Roviana rail | Western Solomon Islands (New Georgia) | Native: none | 2,500–9,999 individuals (old estimate) | Least Concern LC |
| Gallirallus sylvestris Lord Howe woodhen | Lord Howe Island | Introduced: cats (formerly present; control programme 1976–1982) | At least 1,638 (December 2024) | Endangered EN |
| Gallirallus australis weka | North and South Islands of New Zealand (Stewart Island population reintroduced) | Native: none Introduced: stoat, ferret, cats, dogs | 71,000–118,000 mature individuals | Vulnerable VU |
Table notes: Scientific names follow the eBird and AviList systems; in that system Aramidopsis plateni and Megacrex inepta are not placed in Gallirallus. The carnivoran column lists only items for which a source was found; a blank means not yet checked, not that none exist. Population figures are estimates from different sources, made in different years and by different methods; a blank means no reliable figure. IUCN categories may be updated, so please check the IUCN website for the latest status.
References (table)
- Ministry of the Environment, Japan: Okinawa rail conservation and propagation project, Biodiversity Center of Japan: Okinawa rail (Red List / Red Data Book) (both in Japanese)
- IUCN Red List (check the site for the latest categories)
- BirdLife DataZone: Drummer rail (invisible rail)
- Wikipedia: Okinawa rail, Calayan rail, Guam rail, Snoring rail, New Guinea flightless rail, Pink-legged rail, Woodford’s rail, Lord Howe woodhen, Weka
- BirdForum Opus: Roviana rail
- Smithsonian National Zoo: Guam rail
- NSW Government: Lord Howe woodhen population survey
- Carnivoran information: Fauna of New Guinea, List of mammals of the Solomon Islands, Wildlife of New Zealand, Sulawesi palm civet
- Kirchman (2012) (species list)
Threats to the Okinawa rail
1. Invasive Small Indian Mongoose
The Small Indian Mongoose was introduced to Okinawa in the past with the hope of reducing the Habu viper population. However, after spreading to northern Okinawa, they began preying on the Okinawa rail, causing a rapid decline in the rail’s population. Thanks to the efforts of the “Mongoose Busters” (anti-mongoose task force), the mongoose population in the Yambaru region has significantly decreased, and the number of Okinawa rails is currently recovering.
2. Invasive Feral Cats and Dogs
Abandoned pet cats and dogs in the Yambaru region can become feral and prey on local wildlife, including the Okinawa rail. The Okinawa government is actively promoting measures such as microchipping and neutering/spaying for pets. If stray cats or dogs are spotted in the mountains, they are captured using traps and announced on the Kunigami Village website. If no owner is found, they are put up for adoption.
3. Roadkill
Based on records from 2011 to 2026 (through October), between about 19 and 47 traffic accidents involving the Okinawa rail are confirmed each year, and 40 had already been confirmed from January to October 2026, more than in any full year since 2015. By month, accidents are most frequent in May, followed by June and April, which is the breeding season. During this period, adults frequently forage by the roadside to feed their chicks, increasing the risk of being hit by vehicles. Japan’s Ministry of the Environment also warns that early morning and evening are when the rails are most active, so extra care is needed. Drive carefully at all times in the Yambaru region to avoid roadkill.
Data source: Yambaru World Heritage Center Ufugi Nature Museum: Roadkill information (2011–2026, compiled by the author; in Japanese), Ministry of the Environment, Japan: press release on increased Okinawa rail traffic accidents (2014, in Japanese)
If you find an injured Okinawa rail (or accidentally hit one), please immediately contact the Yambaru Wildlife Conservation Center (0980-50-1025) or the NPO Animal Hospital Okinawa (090-6857-8917). Tell the conservation staff your location. If you are on a prefectural road, look for the blue road sign indicating the road number (e.g., Prefectural Road 70), the location name (e.g., Sosu), and the kilometer marker.
Field photographs taken during our tours, with observation dates
During the 【Night Birding】 tour, we can frequently observe Okinawa rails roosting in trees at night. Based on past experience, during periods of low winter temperatures or during the incubation period starting in April, the rails often do not choose to stay in trees overnight; thus, observation chances are relatively lower during these times.
The best season to observe roosting Okinawa rails at night is usually August and September, when the chicks are learning to climb trees. During this time, there is a chance to see juveniles perched on lower branches. On the night of August 17, 2025, we observed 14 Okinawa rails, and on September 16, 2025, we observed 18.
Additionally, during the 【Morning Birding】 tour between April and July, there is a chance to observe Okinawa rails brooding their young during the day.
