Bird distribution and conservation in the Ailao Mountains, Yunnan, China.

摘要

Results from a long-term ecological study conducted in the Xujiaba Ecological Reserve within the Ailao Shan Nature Reserve, Yunnan, China, during 1986-96 indicated the importance of the Ailao Mountains as a sanctuary for numerous bird species considering that natural forest cover is decreasing throughout Southwestern China and adjacent Southeast Asia. Bird diversity was analysed using line transect surveys in 3 different ecosystems: primary broad-leaved evergreen (Lithocarpus spp.) forest on the crest of the Ailao Mountains, and 2 secondary pine (Pinus yunnanensis) forests (regenerating from clear-cut evergreen broad-leaved forest), on the eastern and western slopes. The primary forest (30 ha plot) exhibited the greatest diversity of bird specieswith 169 species in the summer and 107 in the winter compared to 98 and 75, respectively, for the western slopes and 72 and 49, respectively, for the eastern slopes (both 40 ha plots). A large local seasonal migration was observed between the crest of the mountain range and the slopes as well as increasing numbers of long-distance migrants. The variety of ecosystems supported a large variety of bird species including 218 within the Ecological Reserve and 365 in the greater Northern Ailao Mountains. Because of a seasonal local migration, forest ecosystems outside the Reserve need preservation as well as forests inside the Reserve.