Abstract
A young White-tailed Eagle Haliaeetus albicilla was observed for a total of 25 times between May and November 1999 at Nakanokamishima and Iriomotejima of the southern Ryukyu Islands. Since the eagle had a few primary feathers of both wings missing at the same spots, it was identified as the same individual. This is the first over-summering record of the species in the Ryukyu Islands. The bird frequently visited Nakanokamishima which provides breeding sites for six seabird species including Brown Boobies Sula leucogaster and Sooty Terns Sterna fuscata , and some breeding grounds of Black-naped Terns S. sumatrana and Roseate Terns S. dougallii around Iriomotejima. The eagle was repeatedly observed to circle above, approach quickly and land on the seabird colonies or swoop down on feeding flocks of terns. Some carcasses of Brown Boobies and Sooty Terns whose breasts and bellies were eaten were discovered on Nakanokamishima. In addition, terns abandoned their eggs in the breeding colonies around Iriomotejima, suggesting that the White-tailed Eagle over-summering in this area had a both direct and indirect impact on the breeding seabirds.
