The Analyses of Structure of the Woodland Bird Communities in Japan

III. Annual Variation of Breeding Community

Abstract

Annual variation of breeding woodland bird communities was investigated at several plots for 4-12 years by territory mapping method. In young planted forests, number of territories increased or decreased in many species, showing certain trends, but the total number of territories in each plot increased year after year. However, the composition of dominant species-group did not change during the study period at each plot, except immediately after planting. In mature or natural forests, relatively few species showed trends of increase or decrease of territory numbers. The territory number fluctuated irregularly in each species, but this fluctuation did not exceed the twofold of annual mean. Coefficient of variance (C=σ/m) of total number of territories at each plot remained at more or less 10%. Breeding bird densities were affected variously by deforestation or weeding. Similarity indices of bird communities (Whittaker 1952) of each study area were calculated, and similarity dendrograms were composed. Annual data of bird communites at each study area were compared by χ² homogeneity tests. Except for casual effects of deforesting or weeding, the structure of bird community in temperate zone forests would not change significantly within a period of about ten years, and the climax forest would persist unchanged for much longer period.