Distribution and Ecology of Birds of Japan

Abstract

The effects of island biogeography are clearly seen in the avifauna of Japan. Species composition and distribution reflect Japan's geographic, climatic, vegetational, topographical, and geological characteristics. It is a country composed primarily of mountainous, forested islands that lies off the coast of a continent rich in bird life. Though Japan has a wide range of climates and diverse forest habitats, the terrestrial and freshwater avifauna is depauperate when compared with species, family, and order diversity on the nearby continent, which is both larger in total area and more diverse in habitats. However, the bird groups that do have higher species diversity in Japan than in the Asian mainland are seabirds. The large, productive ocean area and small, isolated islands provide them with foraging and nesting sites, and the long geographic range of Japan allows seabirds from both northern and southern regions to nest in the Islands. Island biogeography also affects the ecology of many terrestrial species. Niche shift and expansion of foraging and parasitic behaviors are seen in populations established on islands where the species composition does not include certain competitors. The terrestrial species resident on small islands have developed unique breeding behavior, in comparison with their conspecifics on larger islands, such as smaller clutch size, exaggerated begging behavior, and longer parental care in small-island populations of Varied Tits, Parus varius Temminck & Schlegel.