The volcanic islands of Ogasawara (or Bonin) lie in the north Pacific Ocean, c.1,000 km south of Honshu (Japan), and south of the Izu Islands (EBA 146; see p. 454 for map). The largest of the 20 islands, Chichijima and Hahajima-the only ones which are inhabited-are a little over 20 km² in area, and were once covered in subtropical evergreen forest.

The Ogasawara Islands have been identified as an EBA on the basis of one extant endemic species and a further three extinct endemic species.

Apalopteron familiare survives only on the Hahajima group, having become extinct on Chichijima (although there were reports in 1987 that it may still exist there, or, more likely, have been reintroduced) and apparently also on Mukojima (Brazil 1991). Recent molecular work indicates that this species belongs to the white-eye family (Zosteropidae) rather than being a honeyeater (Meliphagidae) as formerly believed and as indicated by its English name (Springer et al. 1995).

The islands were uninhabited until 1830 but today the human population stands at c.2,000, the result of transmigration from the Japanese mainland and the archipelago has now been widely deforested and cultivated and the natural vegetation destroyed by the grazing of goats (WWF/IUCN 1994–1995, Tomiyama and Susuki 1996).

All the restricted-range species will have been affected by this habitat loss within their small ranges and it is likely that cats and rats, which escaped from whaling boats pulled ashore for repair (Greenway 1967), also contributed to their demise, and that hunting was a further factor.

Although the one surviving restricted-range species, Apalopteron familiare, is common and widespread on Hahajima itself in a variety of different habitats and in modified forest at higher elevations, it is considered threatened because of its tiny range and consequent permanent vulnerability to chance events. The fact that this species has already been extirpated from at least two islands is testimony to this.

Plans to construct a new airport on the island of Anijima (a tiny and relatively intact island 500 m from Chichijima), which could have increased the chance of invasion by additional exotic species (Tomiyama and Suzuki 1996), have been halted but are under consideration for the main island of Chichijima (J. Minton in litt. 1996).

In 1972, 61 km² of the islands were designated as a national park and an active conservation programme is underway including the propagation and reintroduction of threatened native plants (WWF/IUCN 1994-1995).

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: Ogasawara Islands. Downloaded from https://datazone.birdlife.org/eba/factsheet/147 on 22/11/2024.