Function of restored wetlands for waterbird conservation in the Yellow Sea coast

To reduce the harm to wildlife caused by habitat loss and degradation, significant resources have been invested in habitat restoration worldwide. However, whether restored habitats can support wildlife communities similar to those natural ones remains unclear. Providing habitat for waterbirds, which are dependent on wetland for their survival, is a major target in many wetland restoration practices. Here we conducted a year-round waterbird survey at Chongming Dongtan, a national nature reserve established for waterbird conservation in the south Yellow Sea, in order to compare the characteristics of waterbird communities in four wetland types: restored wetlands, natural tidal wetlands, and two artificial wetlands (fish ponds and farmlands). We determined whether waterbird diversity and species composition differed among the wetland types. The results indicated that waterbird diversity, in terms of species richness, individual density, Shannon-Wiener diversity, functional diversity, and phylogenetic diversity, was generally similar in the restored and natural wetlands and was higher in the restored and natural wetlands than in fish ponds or farmlands. Most threatened species and exclusive species occurred in both natural and restored wetlands, but the overall species composition significantly differed between natural and restored wetlands. Non-metric multidimensional scaling analysis also indicated that waterbird community significantly differed among the wetland types. The results suggest that restored wetlands support substantial waterbird diversity but cannot replace natural wetlands because they lack the period tides that many tideland specialists (shorebirds) depend on. This study highlights the importance of protecting natural wetlands for waterbird conservation. We propose that both the diversity and species composition of wildlife communities should be considered in evaluating the effectiveness of habitat restoration for wildlife.