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| Wetland losses and degradations worldwide have resulted in dramatic declines of wetland-dependent waterbirds populations and their habitats. Effective conservation plans to provide essential habitats for waterbirds in periodically inundated wetlands should be based on a deep understanding of the strong relationship between habitat availability and the hydrological regime. Based on waterbirds survey and remotely sensed image classification at various water levels, we investigated how habitat availability for wintering waterbirds responded to water level fluctuation in the Shengjin Lake, a newly designated Wetland of International Important in the middle and lower Yangtze River floodplain, China. During the field survey in the winter 2014-2015, we recorded up to 38 564 individuals of 47 waterbirds species, which could be categorized into four foraging guilds that primarily occur on grassland, mudflat, shallow water or deep water. Habitat availability for wintering waterbirds of all foraging guilds exhibited significant responses to the seasonal water level fluctuation in the lake. At high water level, deep water dominated the lake and could reach up to the peak of 14 500 ha. Along with the water recession during the wintering period, riparian grounds were gradually exposed to provide habitats for waders, shorebirds and geese, which could occupy more than 50% of the lake. The water level fluctuation also affected the landscape metrics, specifying in the increased diversity and decreased fragmentation of the riparian habitats during the water recession period. The artificial regulation of water level, however, changed the natural transition between aquatic habitats which would ultimately affect waterbirds diversity and distribution. We suggest stepwise water recession plans to facilitate waterbird conservation in the lacustrine wetlands in the Yangtze River floodplain, together with recovery of aquatic vegetation community, to synchronize exposure of foraging habitats with migration phonologies of different waterbirds guilds. |
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| Keywords:Ecology; habitat availability; Shengjin Lake; waterbirds; water level; wetland degradation |
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