破碎棲地之面積、孤離度與棲地異質度對都市地景之鳥類群聚組成之影響－以台北市公園綠地為例

Urban forest fragments are potential 'habitat islands' for urban birds. Landscape structure of the fragments may influence the composition of bird assemblages. Hence, this study assessed the effects of fragment size, isolation and habitat heterogeneity on bird community composition patterns in urban parks (and green areas) in Taipei. Species composition in urban parks showed a high degree of nestedness, which was associated with park areas, distance to the major rivers in Taipei and habitat heterogeneity. The high degree of nestedness in bird assemblages demonstrated that the parks may be a network of habitats among which birds immigrate and emigrate frequently. However, exotic species may adapt to the fragments more easily than the endemic ones. Park area is the main factor that accounts for species accumulation in the urban parks and the green areas. Bird assemblages in smaller parks are subsets of those in larger parks. Therefore, we suggest that preserving large parks be the first priority. In addition to park area, habitat heterogeneity may affect distributions of specific bird species. Increasing the habitat heterogeneity of parks may attract more species to the parks. Accumulation of birds, especially migrant species, is affected by the relative locations of major rivers to the parks. Rivers may be an important landscape for birds in urban areas of Taipei. We recommend adding water resources to parks to attract migrating species, which would enhance avian habitat diversity in Taipei.