大阪市街地の都市緑地の樹林を利用する鳥類を決定する要因

抄録

Bird survey was conducted in 85 urban parks in the breeding season of 2000 in Osaka city, western Japan, to clarify the factors affecting bird species richness and bird community in urban small parks. Eleven species of land birds were observed. As the result of comparison of goodness of fit between a species-log area and a species-log tree area curve, the former fitted better. We made a multiple regression analysis to predict the number of species in the urban parks. Tree area of parks was a positive factor, whereas areas of streets, offices and commercial buildings were negative factors affecting species richness. But the obtained model fit less than that of an earlier study in Osaka Prefecture. The reason may be related to the small number of bird species in urban parks in the central area of Osaka city. Bird communities were classified using TWINSPAN. We recognized three types of bird species groups, such as, “urban birds”, open habitat species and forest species. The result of a discriminant analysis showed that tree area positively affected bird communities in urban parks. Street coverage, and office and commercial building coverage had negative effects. Busy streets and tall buildings will interfere bird movement. We suggest the minimum area of tree stands required for creating adequate habitat for forest birds in an urban area may be about 5 ha.