The results of this study indicate the following points for ecological network planning in Japanese cities.
Protection of large core woodlands. Of course, large habitats are important for not only wintering birds but also breeding birds. In most Japanese cities, there are few large woodlands and the proportion of green coverage is lower than that of European cities. However, we have some large woodlands around cities such as this study area and some remnants of large woodlands and shrine and temple forests within urban area; we can establish ecological networks using such woodlands and forests as core habitats.
Improvement of the ratio of woodland around core woodlands. This study showed that the ratio of woodland within 500 m of urban parks was the most important environmental factor for bird species. In order to introduce forest bird species into the urban area, we have to increase the proportion of woodland near core habitats.
Conservation of tall trees. In cities, including this study area in central Japan, there are not many tall trees, because of the lack of rainfall during the summer season and typhoons. Also most trees in urban parks and along streets in Japan are strongly pruned in winter like “bonsai.” The lack of tall trees affects the distribution of bird species that prefer woodland habitat. As the results of this study showed, all individuals of Parus major were recorded only in the sub-tree and tree layers. We must grow taller trees and select tree species suitable for the climate of this area.
Development of vegetation within urban parks. Many Japanese urban parks have no vegetation and are composed of bare ground and playgrounds. Even if there are trees, herbaceous plants and shrubs are usually pruned. Dense herb – and shrub-layer vegetation provides good habitats for some bird species. Such dense vegetation has been avoided in planning of small parks in urban areas because of security concerns. However, it might be possible to arrange vegetation that is suitable for both people and birds.
