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Ogasawara NP, Tokyo
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In 2017, a drone filmed red-footed boobies nesting together in trees on Minami-Ioto’s hard-to-reach southern cliffs. It confirmed Japan’s first known group nesting site for this seabird.
In 2017, researchers collected the rare Shimakumokirisou orchid on Minami-Ioto—the first specimen from the island since 1936. At a botanical garden, it later flowered in cultivation for the first time, helping confirm its identity.
On August 3, 1889, 3 castaways were found on Minami-Ioto after living there for 4 years. Their rescue led ships to make an annual circuit around the island to look for other survivors.
For years, the only known specimen of this Minami-Ioto endemic weevil was one collected in 1981. In 2017, researchers searching up to the summit found exactly one more.
Seabirds bring nitrogen from the sea to Minami-Ioto, and research found that land crabs help spread it through the island’s food web. These crabs range from shore to summit and feed on seabird remains.
The 2007 expedition recorded 8 ant species on Minami-Ioto; 2 were new to science. One is a brown ant just 2.4–2.8 mm long, with a form unlike close relatives known in East Asia.
A 2007 survey raised the known land-snail count from 4 to at least 13. Four seemed possibly undescribed at the time; 3 were found only on leaves in the cloud forest near the summit.
A 1982 survey recorded 21 bird species on Minami-Ioto, 14 of them new records for the island. It found black storm-petrels nesting near the summit, streaked shearwaters mid-slope, and red-tailed tropicbirds by the coast.
DNA analysis found no genetic exchange between Minami-Ioto’s Iwo-to white-eyes and the population on nearby Iwo-to. Even birds that can fly across open sea can become isolated on separate islands.
Moist air rising up Minami-Ioto’s steep slopes creates a cloud belt above about 500 m, where humidity stays above 90% year-round. The island’s summit reaches 916 m, despite its small area of 3.5 km².
The 1982 survey recorded just one mammal species on Minami-Ioto: the Ogasawara flying fox. Unlike many bats, it is active by day, and researchers saw it eating pandanus and kobugashi fruit.
When waves kept boats from landing during the 2017 survey, researchers swam the final 50 m to shore while carrying supplies. On Minami-Ioto, even starting an expedition can be a challenge.
