During 1992 to 1994,bird communities were investigatcd at Xiaolongmen forest area in Beijing,which includs 6 forest types and 7 altitude zones.Totally 69 birds (8 orders and 21 families) were recorded for 3842 times.The Yellow bellied Tit ( Parus venustulus ) is the only dominant species in our study area,with the record times 13.12% of the total.Bird community classification was based on fuzzy cluster analysis.Four bird communities were classified according to the forest type:Ⅰ.mixing forest,Ⅱ.conifer forest,Ⅲ.Quercus liaotungensis forest and IV.shrubland.As for the altitude in our study area,which is from 1070m to 1763m,seven zones were divided.Two main bird communities exist.Ⅴ.1070～1450m and VI.1450～1763m.Species diversity and similarity indices of each bird community were calculated.The results indicated that indices for group Ⅳ was the lowest with obvious independence,while other three forest bird communities (Ⅰ Ⅲ) were more stable,Group Ⅱ has the highest bird species diversity indices and most species.At Xiaolongmen forest,the most abundant bird area was the mixing forest at the altitude between 1070m to 1450m,with 67 birds recorded (97.10% of total bird species number).The birds around 1450m to 1763m were relatively less,with the species number and density 26.87% and 10.12% of the total,respectively.
