小笠原諸島の海鳥相に対する侵略的外来哨乳類の影響と，その駆除による影響

摘要

The Bonin Islands are oceanic islands located within subtropical zone in the northwestern Pacific Ocean. Breeding of 20 seabird species has been recorded there. Human settlements began in 1830 and the seabird populations have suffered from extensive deforestation, serious exploitation and the in-troduction of invasive species. Especially, the cat and rat predations and disturbances by goats caused devastating impacts. Seabirds serve crucial ecological functions such as the nutrient transport from the sea, the physical disturbance of the soil and the supply of diets for raptors. The local extinction of the seabirds means the loss of such functions and the influences should reach to various plants and animals. Alien mammal eradications have been recently conducted in various locations in the islands, and seabirds preferring open habitats have been expanding their range. However, the ranges of the seabirds breeding in forests, such as the Bonin petrels and the Matsudaira's storm petrels, still remain in limited areas. Since eradications of influential aliens sometimes cause unexpected results, adaptive management is essential for ecosystem restorations.