Unique Ecosystem - Birds
The streaked shearwater is a species of seabird that breed in colonies on uninhabited islands in the Oki Islands. The bird breeds on islands throughout Japan, with Oshima Ōshima in Hokkaido as the northern limit. It is around 49 cm in length, with a wing span reaching 120cm. The bird has grey upperparts, blackish brown spots from the forehead to the nape, increasing to form a sesame-salt pattern on the nape and white underwings. The hook tipped bill is long and slender, and bluish in colour. During the day, the flock fly around the sea in search of fish to feed on. The birds earned their name due to their ability to shear water with their wings when they skim close to the water. The streaked shearwater nest in burrows, dug in the ground with little gravel and a lot of soil. The entrance to their long, horizontal burrows is 15 – 20cm wide, and the depth of the burrow is about 1m. The birds lay eggs in the deepest part of the burrow, covered with leaves and twigs. Ohakajima Island, Hoshinokami-jima Island and Okinoshima Island in the Oki Islands are well-known breeding grounds and have been designated as natural monuments.