Fauna in Yakushima
Yakushima is home to a rich diversity of fauna despite being only some 500 square kilometers in area. Many species are native to this island only, and the mammals tend to be smaller than those on the mainland due to the island’s geology and habitat.
Mammals
Seventeen species and four subspecies of mammal, including the Yakushima macaque (Macaca fuscata yakui) and the Yakushika deer (Cervus nippon yakushimae), dwell in the forests. The macaques and deer have no large mammal predators, unlike those in other parts of Japan where there are bears, boars and foxes. This may be a factor contributing to the small size of Yakushima’s macaques and deer. The island’s separation from the Asian continent and mainland Japan may have led to food shortages, resulting in members of animal species becoming smaller as a way of increasing their populations with limited resource availability. The relatively nutrient-rich food on Yakushima, however, may have also contributed to the higher metabolic rates and limited growth of the deer.
Yakushima macaques are dark gray with dark hands and feet. Their hair, which is thicker than that of mainland Japanese macaques, keeps them warm in the winter even at higher elevations. The macaques inhabit trees all over the island, but mainly in regions from the coast up to the laurel forests at around 800 meters above sea level. They feed on the nuts of ako figs and Chinese banyans in villages and coastal areas, and on the nuts of Japanese chinkapin and red oak in the mountain forests.
Yakushika deer are found in laurel and sugi forests at around 1,200 meters above sea level. They are dark brown in color and feed on tree bark, shoots, and nuts.
Macaques and deer can be spotted along the Seibu-rindo Forest Path. In fact, the animals in the area have become accustomed to humans. Visitors should never offer them food, as doing so will disrupt the animals’ natural foraging cycles.
Birds
Among the 168 bird species confirmed on Yakushima are two subspecies native to the island only, the Eurasian jay (Garrulus glandarius orill) and the varied tit (Parus varius yakushimensis). Dense forests, however, make bird-spotting difficult, and most species are found not in the forests and mountains but at lower elevations. Many migratory birds make a stopover on Yakushima in the spring and autumn, including unusual species like the gray-faced buzzard (Butastur indicus) and Eurasian hoopoe (Upupa epops). The tree sparrow flies over from the mainland but does not nest on Yakushima.
One of the best places for bird-watching is along the path through the primary forest in Shiratani Unsuikyo Ravine, beyond the Satsuki Suspension Bridge. Yokko Ravine also offers bird-watching opportunities in a tranquil landscape of large granite boulders and emerald-green pools.
Insects
Over 3,000 insect species are found on Yakushima, but most are also found on the Kyushu mainland. Yakushima is the northern limit for a small number of insect species, hosting many southern species in the lower mountains and coastal areas. Rare insects, including 147 species of long-horned beetles, live on the island. Butterflies and dragonflies also temporarily stray onto Yakushima from as nearby as the Tokara and Amami Islands, to as far away as Taiwan, the Philippines, and mainland China when propelled by southwesterly winds or typhoons. The rare Wonderful Green Hairstreak (Thermozephyrus ataxus) butterfly, native to Yakushima, is seen only in July and August at altitudes of 600 to 1,300 meters, such as Yakusugi Land, Kosugidani, and Hananoego. Shiratani Unsuikyo Ravine is a good spot for insect observation in general, while Ohko-no-taki Waterfall is popular for dragonfly watching.