Researchers say they have found a new seabird species indigenous to the Ogasawara Islands, a UNESCO World Heritage site some 1,000 kilometers south of Japan's main island.
The scientists, including those from the Forestry and Forest Products Research Institute, say the seabirds were previously considered a subspecies of Audubon's shearwater.
The shearwaters are widely distributed across the Pacific Ocean. They have black backs and a white underbody. They build nests in crevices in rocks.
The research team studied DNA samples from 10 of the seabirds in question and found that they are a separate species from Audubon's shearwater.
It says the seabirds are confirmed to breed exclusively on two of the Ogasawara Islands.
The finding brings the number of indigenous bird species that inhabit the islands to 4.
One of the researchers, Kazuto Kawakami, says the discovery adds to the value of the Ogasawara Islands as a world heritage site.
He says the birds should be protected because they are likely to be vulnerable to non-native predators.