Abstract: The information on waterfowl community structure and habitat utilization is critical for protection and management of the wetland waterfowl. Field surveys on winter waterfowl in the Caohai Nature Reserve were conducted during December 2011 to February 2012. Results show that 30 species of waterfowl were recorded, belonging to 17 genera and 10 families of 6 orders, and dominated with Plaeonaretic species and Holarctic species in fauna. Waterfowl of the Anseriformes are the dominant group both in species and population, consisting of five species, i.e.Fulica atra, Anas Penelope, Anser indicus, Tadorna ferruginea, and Anas strepera,all beyongd 10% in dominancy. However, some rare species like Grus nigricollis and Grus grus also have a certain size of population. Apparent differences were observed between the five habitats typical of Caohai in species composition and population of waterfowl inhabiting therein(Kruskal-Wallis H Test：X² =16.1893, P=0.003). The shallow water zones are the richest among the 5 typical habitats in species diversity of waterfowl and also the highest in Shannon-Wiener Diversity Index(H'=1.079) and evenness index (J'=0.804), whereas, the cultivated land is the lowestin all the three indices (H'=0.345；J'=0.493). Clustering analysis of waterfowl communities shows that the waterfowls in Caohai could be sorted into seven concomitant communities, which varied in distribution with habitat. Therefore, more efforts should be made accordingly on protection and management of the shallow water zone and cultivated land to promote conservation of waterfowl diversity and benign cycling of the wetland ecosystem in Caohai.

Key words: Caohai National Nature Reserve, water birds in winter, community structure, habitat utilization