Factors influencing bird distribution among isolated woodlots on a heterogeneous landscape in Saitama Pref., Japan

Bird communities on the 20 fragmented woodlots in a suburban area were surveyed in the Tokorozawa City, Central Japan, to analyze the factors that influenced the distribution of birds. Our results showed that woodlot area is an important predictor of the number of individuals and the species richness of birds in each woodlot. Based on the species composition of birds in wintering season, the fragmented woodlots were classified into four types by TWINSPAN: those are core woodlots, woodlots surrounding core ones, isolated and small woodlots, and isolated and middle-sized woodlots. By canonical discriminant analysis, it was indicated that the connectivity between woodlots and the vegetation structure are also important factors influencing bird communities. The necessity of controlling these factors for avian conservation was pointed out.