Effect Of Man-made Wetlands On The Conservation Of Waterbirds

As the habitat of waterbirds, wetland ecosystems are among those of the most productive and high biodiversity in the world. They are, however, threatened by the increasing human disturbances. Evaluating the role of man-made wetlands relative to natural wetlands is an important issue for biological conservation, while the most natural wetlands had been lost and degraded in the world. Recently, much attention has been paid to the man-made wetlands. Dongtan of Chongming Island is a wetland of international importance, located at the estuary of the Yangtze River. It is an important stopover site and wintering grounds for waterfowls in the East Asian-Australasian Flyway (EAAF). However, a great area of tidal flats had been reclaimed for economic reasons in the past half century. Most of them had been transferred into man-made wetlands, such as rice fields, aqua-cultural ponds, reservoirs etc. The aim of this research is to fully understand the role of three kinds of man-made wetlands on waterfowls in Chongming Dongtan. First, we compared species richness, density, and behavior of waterfowls, shorebirds and overall waterfowls of natural (i.e. tidal flats) and man-made wetlands (i.e. aqua-culture ponds, rice fields, reservoirs). Then, the effect of factors at the patch level and landscape level of aqua-cultural ponds on wintering waterfowl community was investigated. At last, we studied the effects of water depth on the wintering waterfowl communities. The main results were as follows:1. The composition of waterfowl communities was not same at the different wetlands, while the function of wetland was different for the different waterfowl groups. The aqua-cultural pond was the most important and valuable man-made wetland for the diversity of waterfowls. Species richness and density of waterfowls, shorebirds and overall waterfowls were greatest at the region of aqua-cultural ponds, except the density of shorebirds. Ten species of waterfowls were only observed at the aqua-cultural ponds, which was not only a roost habitat, but also a feeding habitat for waterfowls and shorebirds.The Reservoirs was also important for waterfowls. The density of shorebirds was the greatest at this habitat, species richness and density of waterfowls was obviously higher than that at the tidal flat. Two species of waterfowls distributed only at this type of wetlands. It was a roost and feeding habitat for waterfowls, but only a roost habitat for shorebird. The percentage of foraging shorebirds at the reservoirs was...