UNESCO · Natural · 2011

Ogasawara Islands

小笠原諸島おがさわらしょとうOgasawara-shotō

A laboratory of evolution in the middle of the Pacific

The Ogasawara Islands are a chain of more than 30 oceanic islands in the Pacific about 1,000 km south of central Tokyo, to which they belong administratively. Never connected to a continent, they are a showcase of evolution in isolation — above all among land snails and plants — and were inscribed in 2011.

Inscribed 2011Criteria: ixTokyo

Overview

The Ogasawara Islands, also known in English as the Bonin Islands, lie in the western Pacific on the Izu-Bonin arc, where the Pacific Plate descends beneath the Philippine Sea Plate. They were built by volcanic activity during the early stages of this subduction some 48 million years ago; the rare rock boninite is named after them. The islands have never been connected to a continent, and every plant and animal that lives there arrived across the ocean by wind, currents or birds.

Isolation turned the islands into a natural laboratory. A large share of their vascular plants and the great majority of their native land snails are found nowhere else, and several groups have diversified into many species adapted to different habitats — land snails of the genus Mandarina, for example, into species living in trees, on the ground and in leaf litter. Seabirds, the Bonin flying fox, the Bonin white-eye and green turtles that nest on the beaches are among the other notable inhabitants.

The islands were uninhabited until 1830, when settlers of European, American and Pacific Island origin arrived from Hawaii. Japan formally incorporated them in 1876, and Japanese settlers followed. After the Second World War they were under United States administration until 1968. Today only Chichijima and Hahajima have civilian residents, forming the village of Ogasawara within Tokyo.

Why it is World Heritage

The Ogasawara Islands were inscribed under criterion (ix). They offer an outstanding example of ongoing evolutionary processes in oceanic island ecosystems, demonstrated by the high rate of endemism and the adaptive radiation of land snails and endemic plants, which continue to evolve.

The islands' value is fragile. Introduced species — goats, rats, the green anole lizard, invasive plants and a predatory flatworm that feeds on land snails — have caused severe losses. Eradication programmes and strict biosecurity measures for visitors and cargo are an integral part of the management of the property.

Component sites

Chichijima group
父島列島Chichijima-rettō
The main inhabited island and its neighbours, with dry scrub forest, white beaches and the port of Futami; Minamijima, a small uninhabited island with a drowned karst landscape, is visited only under guidance.
Hahajima group
母島列島Hahajima-rettō
The southern inhabited island, wetter and more forested than Chichijima, with cloud forest on Mount Chibusa and the only habitat of the Bonin white-eye.
Mukojima group
聟島列島Mukojima-rettō
Uninhabited northern islands, once devastated by feral goats and now recovering after their removal; an important breeding site for albatrosses.
Volcano Islands and Nishinoshima
火山列島・西之島Kazan-rettō, Nishinoshima
Kita-Iwo-to and Minami-Iwo-to, steep volcanic islands left largely untouched, and Nishinoshima, whose eruptions from 2013 onward greatly enlarged the island.
Land snails
陸産貝類Rikusan Kairui
Around a hundred native species, most of them endemic; their diversification into different ecological niches is a key example of adaptive radiation cited in the inscription.
Bonin flying fox
オガサワラオオコウモリOgasawara Ōkōmori
The only native land mammal of the islands, a fruit bat designated a Natural Monument.

History

c. 48 million years ago
Volcanic activity at the start of subduction forms the oldest rocks of the islands.
1830
The first settlers, Westerners and Pacific Islanders from Hawaii, arrive on Chichijima.
1876
Japan formally incorporates the islands.
1944
Civilian residents are evacuated to the Japanese mainland during the Second World War.
1968
The islands return to Japanese administration from the United States.
1972
Designation of Ogasawara National Park.
2011
Inscription on the World Heritage List.

Visiting

There is no airport; the passenger ship Ogasawara-maru sails from Takeshiba Pier in Tokyo to Chichijima in about a day, and a connecting ship links Chichijima with Hahajima.
Because of the ship schedule, a visit usually lasts about a week including the voyages; accommodation should be arranged before departure.
Visitors clean shoes and gear at designated mats and follow biosecurity rules to avoid carrying seeds, soil or flatworms between islands.
Some areas, including Minamijima and parts of the forest on Chichijima and Hahajima, may only be entered with licensed guides under local rules.
Whale watching (humpback whales in winter and spring, sperm whales offshore) and dolphin swimming are regulated by local voluntary rules.

Frequently asked questions

How do you get to the Ogasawara Islands?

Only by sea: the Ogasawara-maru ship from Tokyo takes about 24 hours to Chichijima. There is no airport.

Why are they called the Bonin Islands?

Bonin is thought to derive from munin, an old Japanese reading of the characters for 'uninhabited', as the islands had no permanent population before 1830.

Are the Ogasawara Islands part of Tokyo?

Yes. They form the village of Ogasawara, which belongs to the Tokyo Metropolis despite lying about 1,000 km to the south.

Is Iwo Jima part of the World Heritage Site?

No. Iwo To (Iwo Jima) itself is not included; of the Volcano Islands only Kita-Iwo-to and Minami-Iwo-to belong to the property.

Why do visitors have to clean their shoes?

To stop the spread of invasive species, especially a flatworm that preys on the endemic land snails, between islands and into protected areas.

Sources

1.Ogasawara Islands (opens in a new tab) — UNESCO World Heritage Centre
2.日本の世界自然遺産 (opens in a new tab) — 環境省
3.小笠原国立公園 (opens in a new tab) — 環境省
4.小笠原村 (opens in a new tab) — 小笠原村