Nansei Shoto

Wild Japan III: Nansei Shoto & Okinawa

Okinawa: The Little Known Sub-tropical Side

Mark Brazil

To the uninitiated, it is easy to imagine that Japan's four main islands of Hokkaido, Honshu, Shikoku and Kyushu constitute the entirety of the country. Yet that would be to ignore much that is special about the country - its plethora of islands and islets. Japan is truly the ultimate when it comes to island countries, with archipelagos within archipelagos, and with islands and islets galore.

Japan's southern extension is a separate archipelago in its own right - the Nansei Shoto. Justifiably defined as Asia's answer to the Galapagos, the numerous islands in the warm waters between Japan's southern island of Kyushu and the island of Taiwan are fascinatingly different from the rest of Japan.

The Nansei Shoto are astonishingly rich in natural history and provide opportunities for snorkeling, diving, wind-surfing and whale-watching. These though are not the only southern islands of Japan, for head south from Tokyo, out into the Pacific and there lie the Izu, Ogasawara (Bonin) and Iwo islands, the most remote parts of this widespread country.

The Natural Marvels of the Nansei Shoto

Japan's straggling southern archipelago, the Nansei Shoto, is so rich in both flora and fauna, and such a fine example of the effects of isolation that the islands have quite rightly been called the Asian Galapagos. There, the many forces of isolation have contributed to the evolution of many endemic species of plants, insects, birds and even mammals.

The largest of the islands in the chain is Okinawa, but it is far from being the only island of significance. The Nansei Shoto represents Japan's finger in the sub-tropical pie.

Where Hokkaido freezes for half of each year, the Nansei Shoto swelters. Here are flowers, butterflies and trees more commonly associated with the tropics. White coral sand beaches and intense sun add to the image.

Offshore, there are coral reefs with a myriad colourful fish; one may be lucky and find turtles too or even migratory whales here in these warm waters. The local vegetation includes ancient-looking cycads, and forest that is lush, and evergreen with broad glossy leaves. The wildlife here is very different from that in any other part of Japan.

Okinawan Forest.
The canopy of the subtropical forests of Amami and Okinawa are surprisingly uniform in height and rich in species.

Nansei Shoto Wildlife

Not all the islands share the same species, as the history of each is slightly different. These islands have had a fascinatingly chequered natural history. Connection and isolation have played their part here, such that the Kerama and Tokara straits, effectively divide the archipelago in to three parts.

In times past they have experienced long periods of isolation as islands, but when sea levels have fallen they have been connected to the continent. The northern section retained a connection with Kyushu, whereas the southern section retained a connection via Taiwan to the continent.

At other times, all islands have been connected, and at still other times all have been isolated as higher sea levels have separated them, not only into the islands that exist now, but into even smaller fragments.

When connected, species reached the islands from Asia and moved between the islands. When separated, during prolonged periods of isolation, species have diverged, evolved and unique endemic forms are the result.

Few of Japan's familiar mammals occur here, there are no squirrels, foxes, tanuki, or deer. Instead, the largest mammal is a small sub-species of the wild boar. There are other mammals on the islands though and among them are several endemic rodents such as the Ryukyu Spiny Rat, and Ryukyu Long-haired Rat, and the extraordinary forest-dwelling Amami Black Rabbit. The largest predator of the region, the Iriomote Wildcat, was only discovered as recently as 1965. It only lives on one small island and is no larger than a domestic cat.

Okinawa from the air.
An aerial view of Okinawa Island showing its pattern of small fields, forested hills and shallow bays.
Japanese island seen from the air.
The ultimate in isolation, volcanic islands are a challenge for species to reach and colonise, yet many species succeed.

Research has shown that the animals of the northern and southern islands of the Nansei Shoto are still genetically, closely related to those of the main islands of Japan, or of southern Asia, from which they have only recently diverged, but the animals living on the central islands of Okinawa and Amami tell a different story.

Genetic research has shown that the spiny and long-haired rats and the rabbit on Amami are so distinct that they are considered not only to belong to distinct species, but also to belong to distinct genera (the next highest category in which species are grouped). These species are living witnesses to the ancient isolation of these fascinating islands.

Birds such as the Cinnamon Bittern reach their northernmost limits here, while Japanese Macaques on Yakushima are at their southern limit. Still other species have evolved or survived in situ and are found no where else in the world, such as the Black Rabbit of Amami Island, and the rare Pryer's Woodpecker of northern Okinawa. New species are still being discovered in this hot-house of biodiversity, and in the early 1980s even a new bird, the Okinawa Rail, was described.

Humpback Whale.
The marine environment surrounding Japan is a very rich one, and among the many species migrating past the islands are Humpback Whales.

The Natural Marvels of the Izu and Ogasawara Islands

"Archipelagos within archipelagos" is perhaps the best way to sum up Japan's geography. In almost every direction one heads, there are not just islands, but strings of them.

Even metropolitan Tokyo consists of an island chain. On the mainland of Honshu is situated the huge urban island of Tokyo itself, but head south by ship and you can travel for a 1,000 km and more and yet still be within the official metropolitan area!

The first islands encountered are the Izu Islands, which are easily reached overnight by ship from Tokyo itself. Here the climate is warmer, more oceanic, the islands have a delightful world-in-miniature feel, and from a natural history perspective they are home to some unusual endemic species.

Approaching them early in the morning, islands such as Miyake-jima are encircled by swarms of seabirds, for these islands are the breeding haunts of hundreds of thousands of Streaked Shearwaters. The warm waters offshore are popular with dolphins making dolphin watching a distinct possibility, particularly off the island of Mikura.

Onshore, in the evergreen laurel forests that clad the flanks of the local volcanoes there are special birds such as the local Izu Islands Thrush and Ijima's Warbler, both of which can be seen easily seen on the islands of Miyake and Mikura.

Further south still there is a remote volcanic rock jutting from the sea known as Torishima - literally bird island. This spot on the planet is world-famous because each year the beautiful and exceedingly rare Short-tailed Albatross returns here to breed. From near extermination, early in the 20th century, concerted efforts by scientists, local government and conservationists have seen their numbers climb back in to the low hundreds and reach relative security once again.

The island chain does not end here though. Way beyond Torishima, and a 1,000 km south of central Tokyo, lie the Ogasawara Islands, also known as the Bonin Islands. These tropical pacific islands are a far cry from downtown Tokyo, though still linked by local administration and local telephone charges. In their extreme isolation they have few species of birds, though the Bonin Islands Honeyeater is endemic here, but for botanists Chichi-jima and Haha-jima are tropical island paradises.

The islands have now attracted fame as a superb whale-watching destination where Humpback and Sperm whales are both likely, and they offer excellent snorkeling and diving too, and as a place to relax and unwind in tropical warmth, then few places can beat the isolated Ogasawara Islands.

Humpback Whale surfaces.
A Humpback Whale surfaces, exhales and reveals its extraordinarily elongated white pectoral fins.

Related Articles on Japan

Japan Geology
Japan Geography
Japan Climate
Wild Hokkaido
Wild Honshu

Text + images by Mark Brazil

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