Abstract:

Composition of waterbirds community was surveyed in the Qiantangjiang River Estuary and the Hangzhou Bay in the winters of 2007,2009 and 2011.A total of 69 species were recorded and they belonged to 7 orders and 14 families.Among these bird species,45 species (652 percent of total) were migrants,7 species were national firstgrade protected wildlife.For 6 species,maximum counts exceeded the 1% of the biogeographical flyway population.The waterbirds were divided into five dominant groups:shorebirds (Charadriiforms),waterfowls (Anseriformes),the Rallidae and gulls (Laridae,Sternidae).And the dominant species were Dunlin (Calidris alpina) in shorebirds group,Falcated Duck (Anas falcata),Spotbilled Duck (Anas poecilorhyncha),Common Teal (Anas crecca),Eurasian Wigeon (Anas penelope) in waterfowls group,Common Coot (Fulica atra) in the Rallidae group and Vega Gull (Larus vegae),Yellowlegged Gull (Larus cachinnans) in gulls group.And 65,38,37 and 28 species were recorded in Cixi County,Shangyu County,Zhenhai County and Haining County,and accounted for 942%,551%,536% and 406% of total,respectively.The community compositions from four abovementioned key areas were analyzed by using species numbers or individual number of five dominant groups.The species richness of shorebirds,ducks and gulls in Cixi County was remarkably higher than that in the other areas,while there was no significant difference in the number of shorebirds species between the former and Zhenhai County.In Cixi County,the population of shorebirds and ducks were also larger than that in the other areas except that there was no significant difference in the population of ducks between the former and Shangyu County.From 2007,2009 to 2011,there were little changes in the community diversities of wintering waterbirds,but great change occured in the population size of waterbird community and this was mainly due to the changes of the population sizes of shorebirds,the Rallidae and gulls.Over four years (2007-2011),waterbird numbers increased,from the maximum count of 41 712(2007) to 54 393 (2011).The individual number of the Rallidae increased quickly,from the maximum count of 58 (2007) to 17 171 (2011),but that of the gulls declined quickly,from 4 947 (2007) to 1 845 (2011).The results showed that wetland resource availability was the key factor that affected the spatial distribution of waterbirds in the Hangzhou Bay and the Qiantangjiang River Estuary.Recently,the intensive reclamation in the studied area maybe play a key role in influencing the community composition and structure of wintering waterbirds.Artificial wetlands after tidal reclamation can provide important wintering habitats for waterbirds,such as tideland reservoirs were particularly important for waterfowls and shorebirds,new reclaimed but not yet developed areas for waterfowls and the Rallidae.The surface area of the two abovementioned habitat types of artificial wetlands has increased over the study period,and waterbird species such as Common Coot concentrated in these artificial wetlands have tended to increase.Garbage resources are generally of importance in several large gull species such as the Yellowlegged Gull’s diet.The reduction of the amount of garbage from the upper reaches of the Qiantangjiang River may be the reason that has resulted in a sharp decrease of the individual number of gulls from 2007 to 2011.Therefore,for the purpose of bird conservation,the local governments should take actions to protect and use natural wetlands reasonably and efficiently.On the same time,appropriate management is needed to improve the quality of artificial habitats