The importance of artificial habitats to migratory waterbirds within a natural/artificial wetland mosaic, Yellow River Delta, China

Summary Anthropogenic conversion of natural wetlands into artificial wetland habitats has produced complex wetland landscapes worldwide. In this study we investigated the responses of migratory and wintering waterbirds to five artificial wetland habitats (aquaculture ponds, paddyfields, irrigation canals, open water reservoirs and saltpans) within a novel natural-artificial wetland landscape, Yellow River Delta (YRD), eastern China from October 2007 to May 2008. The results showed that almost all bird community indicators in the YRD natural wetlands were higher than those in adjacent artificial wetlands. Across the landscape, natural wetlands remained most important for all waterbird guilds, and more than 90% of waterbird populations were dependent on these habitats. Artificial wetlands mainly provided a secondary role, supporting about 70% of waterbird species (including six species that reached 1% of their global or biogeographical flyway populations), but with distinctive functional capacity for specific waterbird guilds in different artificial wetlands. The conservation value of artificial wetlands is often ephemeral, mainly during autumn, for specific migratory waterbirds and complements that of remaining areas of natural wetlands. Therefore, the utilisation patterns of artificial wetlands are highly temporal and the majority of species are dependent on areas of natural wetland. A comprehensive study of the inter-seasonal and inter-annual variations in these different habitats and dependence by the various guilds in the YRD is required to enable the true value of these habitats to be understood. We suggest that the conservation of artificial wetlands should not be at the expense of natural wetlands, which should remain the priority for wetland landscape management. Management to maintain the existing artificial wetlands for migrating and wintering water birds should target habitat features that are absent or limited in natural wetlands thus increasing the carrying capacity of the YRD landscape.