Included within this EBA are all islands lying between Kyushu (the southernmost main island of Japan) and Taiwan (EBA 149). There are over 100 islands, belonging to Japan and divisible into several distinct groups including Danjo, Osumi and Takara in the north, Amami and Okinawa in the middle, Sakishima (main island Ishigaki) and Yaeyama (main island Iriomote) in the south, and Daito to the east. The archipelago is sometimes called the Ryukyu Islands, but there is some ambiguity concerning the correct usage of this term (see Brazil 1991), and thus Nansei Shoto is used here in preference.

The northern islands' characteristic vegetation is temperate forest, while south of Amami subtropical evergreen forest predominates. However, altitude is also influential, and a broad cross-section of habitats can be found on single islands. Thus, on Yakushima, which reaches 1,935 m (the highest point in this EBA), there is subtropical forest on the lower slopes, mixed deciduous and coniferous forest at higher altitudes, and alpine habitats on mountain peaks.

The northern limit of the Oriental faunal region and the southern limit of the Palearctic intergrade in the Nansei Shoto which consequently harbour birds (often endemic races) from both these regions as well as their own unique species. The islands are also important for migrating and wintering birds (see 'Restricted-range species', below) and for colonies of breeding seabirds (WWFJ 1984, 1985, Brazil 1991; see 'Threats and conservation', below).

All the restricted-range species are forest birds, several also being recorded from secondary and man-made habitats. Five species are confined to Amami and Okinawa only. Ryukyu Serpent-eagle Spilornis (cheela) perplexus, endemic to Sakishima and Yaeyama, is sometimes treated as a full species (e.g. Brazil 1991), but has not been included here.

Two restricted-range species from the Izu Islands, Izu Thrush Turdus celaenops and Ijima's Leaf-warbler Phylloscopus ijimae, have recently been recorded breeding in the Takara Islands in this EBA (Higuchi and Kawaji 1989, Kawaji et al. 1989), but because the records are c.1,000 km from the species' core ranges, and the numbers involved are very small, the Izu Islands have been treated as a separate EBA (146). A further two restricted-range species are recorded in the Nansei Shoto as non-breeding visitors: Japanese Night-heron Gorsachius goisagi and Yellow Bunting Emberiza sulphurata (both from central Honshu, Secondary Areas s089 and s090).

This EBA has already suffered the extinction of one bird species: Columba jouyi was last seen on Okinawa in 1904 and on the Daito Islands in 1936, but its full range was never documented and its demise remains inexplicable. Today, five species are considered threatened owing to deforestation within their small ranges, as, on some islands, much of the native subtropical vegetation has been cleared for agriculture, settlement and plantations of pine and pineapple.

The two Okinawa endemics, Gallirallus okinawae and Sapheopipo noguchii, are restricted to the mountainous northern third of Okinawa (known as Yambaru) where the main threats are: dam construction and associated road-building, forest cutting to make chipboard, and clearance for cultivation, especially of fruit. G. okinawae, a flightless species only discovered in 1978, is estimated to number 1,800 birds, and S. noguchii c.100 birds in less than 15 km² of suitable undisturbed habitat. The two Amami endemics, Zoothera major and Garrulus lidthi, also have very restricted distributions because much mature forest has been clear-felled in the last few decades; Z. major is estimated to be below 100 individuals and G. lidthi c.5,800.

Predation by mongooses, introduced to Amami and Okinawa to control poisonous snakes, may prove a serious threat to the endemics, and already appears to have caused a population decline of Scolopax mira in part of Amami. Introduced predators are a threat to the Japanese Murrelet Synthliboramphus wumizusume (classified as Vulnerable), a seabird only known to breed on small islands/stacks in southern Japan and South Korea. In this EBA, it breeds in the Danjo Islands, where the destruction of nesting habitat and disturbance by fishermen landing at breeding sites may be an additional problem.

All the threatened species have been designated as 'Natural Monuments', which gives them a degree of protection from some threats (e.g. hunting, which was a significant threat to Garrulus lidthi). However, this does not automatically lead to the protection or conservation of forest and there is only one reasonably sized protected area on Iriomote. On Okinawa, a key island for the conservation of restricted-range species, only small parts of Mt Yonaha, Mt Ibu and Mt Nishime are designated as protected areas by the government (Ichida in press). However, the US Air Force has a large base in Yambaru, covering some of the best areas of forest, and it is hoped that some of this can be designated as a national park.

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: Nansei Shoto. Downloaded from https://datazone.birdlife.org/eba/factsheet/146 on 22/11/2024.