Japan & Taiwan

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Japan and Taiwan Bat Conservation The fruit bats of the Bonin and Ryukyu islands of Japan represent the most northerly limit of the Pteropodidae range. They comrise the four endemic subspecies of the Ryukyu flying fox Pteropus dasymallus; the Bonin fruit bat P. pselaphon (endemic to the Bonin Islands), and the endemic subspecies P. mariannus loochoensis. The Okinawa fruit bat, P. loochoensis, which was endemic to south-east Okinawa and the Ryukyi Islands, is considered to be extinct by the IUCN (Baillie &Groombridge, 1996).

Pteropus dasymallus Temminck, 1825. IUCN grading: Endangered A1c, e (Baillie & Groombridge, 1996). The Ryukyu Flying Fox occurs on Kuchinoerabu Island and the Tokara Islands (Takara-jima), Kago-shima and Nakano-shima, Taira-jima and Akuseki-jima, the Yaeyama Islands and at one time the Nansei Islands of Taiwan. It is once thought to have lived around Kago-shima city and Okinoerab Island (Y. Osawa, pers. comm.). A study of P. dasymallus >dasymallus on the warm-temperate Kuchinoerabu island revealed their diet to be the most diverse of any pteropodid bats yet studied. The diet includes bark, 17 species of fruit, nine species of leaves, five species of flowers and eight species of insects, which are believed to provide an essential protein supplement (Funakoshi et al., 1993). Fruit forms the bulk of the diet, with flowers eaten only in the spring, insects in the summer and autumn, and leaves at all times of the year.

Pteropus loochoensis Gray in 1870. IUCN grading: Extinct (Baillie & Groombridge, 1996) The Okinawa Flying Fox is believed to have lived on Okinawa and the Ryukyu islands, but has not been sighted since its initial description in 1870. The species is now regarded as extinct (Baillie & Groombridge, 1996). Little information exists on this species and the only two specimens in existence are held in the British Museum. They have a blackish coloured body with short fur and a pale mantle (Y. Osawa, pers. comm.).

Pteropus pselaphon Lay, 1829. IUCN grading: Vulnerable B1 & 2c (Baillie & Groombridge, 1996) The Bonin Fruit Bat (P. pselaphon) is endemic to the Ogasawara islands (Bonin Islands) where it is found in small numbers on of Haha-jima and Titi-jima, and the Volcano Islands (Kazen-retto) of Iou, Minamiiou and Kitaiou/Hokou (Anon., 1991). The fur is long and almost completely black, except for a scattering of silver hairs. They lack the typical pale mantle of P. dasymallus and other Pteropus species. The Bonin fruit bat forms large, permanent camps in Titi-jima island from January to April. They gather in large, noisy agglomerations about 30 minutes after sunset before flying to their feeding sites. They are then highly active, feeding and socializing for two or three hours before dispersing. Just before dawn they return to the roost to sleep (Y. Osawa, pers. comm.). On Minamiiou the fruit bats appear to be most active during the day (Anon., 1991).

On Haha and Titi the populations have become so small that the possibility of extinction in the near future can not be ruled out (Anon., 1991). On the uninhabited islands of Kitaiou (bat population unknown) and Minamiiou (population estimated at a few hundreds in 1982 [Ishii, 1983]) the cause of the population decline is unknown, but development and loss of suitable habitat and food plants have been implicated (Matsumoto, 1978 & 1980). Over hunting in recent decades is certainly likely to have been a factor. Reports of an annual harvest have been reported since 1968 (Hasuo, 1969). Listed as 'Vulnerable' in the Japanese Red Data Book (Anon., 1991), these bats have had protection from the Agency of Cultural Affairs and the Environment Agency on the Japanese government since 1968. Most of their range of distribution is within protected areas, since the Japanese government designated the islands a national monument in 1969, limiting further disturbance (H. Ota [p.98] in Mickleburgh et al., 1992).

Threats and Protection

Both P. dasymallus and P. pselaphon have been protected as national monuments by the Japanese government since 1968, but although the laws protecting these bats prevent their direct destruction they do not extend to the protection of their habitat (Anon, 1991). Logging, under-planting and deforestation, especially on the Ryukyu islands, Ogasawa-shato and the Volcano> Islands (Kazan-retto) and the clearance of forest for the growing of sugar cane and fruit have removed a considerable amount of the fruit bats' natural habitat, depriving them of food plants and roosts. This is thought to be the main cause of the rapid decline of populations of fruit bats in recent decades. Although the Bonin Islands are protected the bats are probably still hunted there (H. Ota [p.98] in Mickleburgh et al., 1992). Some damage to banana, papaya and mango crops is reported but although no figures are available, it is thought to be negligible. Farmers are forbidden to destroy the fruit bats, although they are not compensated for damage to their crops, which they sometimes protect with exclusion netting (Wahl, 1993).

Suggested Action

Surveys and long term monitoring of the populations on the islands and the degree of threats from hunting and habitat loss are essential. Tighter regulations for the protection of habitat and roosts, designation of protected areas and re-vegitation on Ryukyu are needed (Anon, 1991). Investigation into the prevalence of hunting on the Bonin islands is also needed, which should be brought under control (H. Ota [p.98] in Mickleburgh et al., 1992).

Taiwan

A fifth P. dasymallus subspecies, the Taiwanese fruit bat P. d. formosus, existed on the Nansei islands, to the southeast of Taiwan main-island. They were heavily hunted in the 1980s and received no protection while the country was under Chinese rule (Hsu, 1997). They now receive protection under the Wildlife Conservation Law (1998), which is upheld by the Department of Forestry, Council of Agriculture, but are widely believed to be extinct in the wild (Hsu, 1997; Baillie & Groombridge, 1996) This is thought to have come about through habitat loss and over-hunting (Hsu, 1996).

Information on this page was compiled and authored by Oliver Thatcher and is currently being updated.

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