Factors influencing avian species composition recorded in urban and suburban small wooded patches

Urban matrix is often considered to be an area contributing to urban biodiversity quite a little. Recent studies indicated, however, some small patchy habitat such as private gardens, pocket parks and other kind of small vegetative patches may support certain ecological communities. We surveyed avian species composition in 125 small (50 - 20,000 m2) wooded patches within urban or suburban landscapes during both wintering and breeding seasons in and around Tokyo, Japan. The results indicate that the most apparent community gradient can be considered to represent urbanization gradient that has a significant relationship with patch size and vegetation coverage of tree layer. The distance between the small patch and the nearest large (5ha or larger) patch and landscape scale urbanization estimated from satellite imaginary showed a significant relationship with the community gradient only in wintering season. This result could be explained considering the fact that the mobility of avian individuals tends to be higher in winter than in breeding season.