Relationship between Avian Diversity in Middle and Large Woodlots in Urban Areas and their Surrounding Environment

Abstract

We examined relationship between avian diversity in urban woodlots and the surrounding environment. We surveyed bird communities and vegetation structures in 9 woodlots (6.87-52.26 ha) in Tokyo Metropolis and Saitama Prefecture during both wintering and breeding seasons in 2005. We measured area, latitude, and longitude of each woodlot by GIS, and estimated quality of the surrounding environment of each woodlot, using NDVI values in 250 m and 2,500 m buffers of each woodlot calculated from EOS-Terra/ASTER satellite imagery. We analyzed relationship between bird species richness and vegetation structure by correlation analysis, and constructed multiple regression models explaining bird species richness, using woodlot area, latitude, longitude, and surrounding environment. Effect of woodlot area and the amount of vegetation cover in each layer on bird species richness was little in both seasons. Total and migrant bird species richness in wintering season was explained by latitude, longitude, and NDVI in 2,500 m buffers. Resident bird species richness in both seasons and bird species richness in breeding season were explained by latitude, longitude, and NDVI in 250 m buffers. Influence of surrounding environment on migrant bird species and that on resident bird species may differ.