安徽沿江浅水湖泊越冬水鸟群落的集团结构

长江中下游湖泊是越冬水鸟的重要栖息地,随着湖泊渔业养殖强度的不断加大,湖泊湿地严重退化,水鸟的越冬生态受到影响。为揭示长江中下游浅水湖泊越冬水鸟对湿地资源的利用特征,2008年12月至2009年3月,通过扫描取样法采集安徽省长江沿江升金湖、菜子湖和武昌湖3个浅水湖泊30种越冬水鸟的取食行为百分比数据,利用聚类分析法对越冬水鸟进行集团划分,并采用无倾向对应法(DCA)分析越冬水鸟的取食特征。聚类分析结果表明,安庆沿江湖泊越冬水鸟群落可分为4个集团,即深水取食集团G1、挖掘和啄取集团G2、浅水取食集团G3和泥滩拾取集团G4。G2集团的鸟种最多,共有13种,优势种为鸿雁(Anser cygnoides)、豆雁(Anser fabalis);G3集团次之,共6种,优势种为小天鹅(Cygnus columbianus)、白琵鹭(Platalea leucorodia);G4集团共5种,优势种为黑腹滨鹬(Calidris alpina)、鹤鹬(Tringa erythropus)和红脚鹬(Tringa totanus);G1集团水鸟种类有6种。这些水鸟的觅食生境主要在湖泊滩涂和浅水区域,其食物资源的可利用性和觅食对策共同决定群落组成结构。DCA分析表明,取食方式及取食时运动方式组成的觅食对策决定了集团食物资源的分割,草滩中取食鸟类主要采用静止取食和啄取方式,泥滩取食集团主要采取拾取及奔-停取食,深水区取食集团则主要采用潜水方式取食,因此,维持湖泊不同区域的丰富食物资源对于保护湖泊丰富的水鸟资源具有重要意义。

Guild structure of wintering waterbird assemblages in shallow lakes along Yangtze River in Anhui Province, China

Shallow lakes in the middle and lower Yangtze River floodplain are important habitats for wintering waterbirds. In recent years, with the impact of fisheries increasing in the lakes, the wetland has become seriously degraded, which has adversely affected the foraging ecology of the wintering waterbirds. To gain insight into the characteristics of inland wetland resource partitioning of the waterbird assemblages in the shallow lakes, we collected data on foraging behavior of 30 waterbird species by instantaneous scan sampling during fieldwork from December 2008 to March 2009. Study sites were in Shenjin Lake, Caizi Lake and Wuchang lake, which are along the Yangtze River in Anhui Province, China. Clustering analysis was used to classify the wintering waterbird assemblages into different guilds. Detrended correspondence analysis (DCA) was also used to analyze the resource partitioning characteristics of the waterbirds. The results showed that the wintering waterbirds could be divided into four groups: deep water foragers (G1), shallow water foragers (G2), peckers and diggers (G3), and pickers in the mudflat (G4). G2 was the largest group with a total of 13 bird species, and of these the dominant species were swan geese and bean geese. The second largest group was G3 with six species, and the dominant species were tundra swan and Eurasian spoonbill. G4 was composed of five bird species, and the dominant birds were dunlin, spotted redshank and common redshank. The smallest group was G1, with only six species. The foraging substrates of the guilds were mainly mud flats and littoral zones. The first main axis of the DCA analysis was associated with wintering waterbird feeding behavior and movement ability; the second axis was associated with waterbird feeding space and foraging mechanism. The results showed that the foraging strategies and foraging sites together explain the partitioning of resources. Foraging behavior, movement pattern and foraging substrate were associated: the wintering waterbirds used different foraging strategies. Marsh birds mainly stayed feeding and pecking, mudflats birds used pause-travel foraging, and deep water birds mainly dived to forage. Thus, feeding behavior and food resources together with foraging strategy determined the characteristics of resources partitioning of the wintering waterbirds in the shallow lakes. Waterbirds in the grasslands mainly foraged by pecking, those in the mudflats used pause-travel foraging while the deep water birds foraged by diving. The results of this study showed that the large number of wintering waterbirds mainly foraged in the lake beach and shallow waters zone, which provide wintering food resources for waterbirds throughout the wintering season. During the wintering period, the decrease in abundance of vegetation and zoobenthos in the shallow lakes of the middle and lower Yangtze River floodplain severely impacts the wintering ecology of migrating waterbirds. We believe that it is important to maintain food availability in the different lake zones during the winter to maintain high waterbird diversity. However, further investigation is required to determine the type of food resources required in the inland lakes along Yangtze River during different periods.