Changes in the waterbird community of the Yangtze River in the Three Gorges Reservoir Region, China, 2003-2013

Water-level fluctuations may affect the abundance and habitat distribution of waterbirds. We surveyed waterbirds in the Yangtze River in the Three Gorges Reservoir Region (TGRR) from January to early February annually from 2003 to 2013 (except 2011) and recorded the locations and numbers of individuals. Based on the survey results, we identified seven species, including the mallard (Anas platyrhynchos Linnaeus, 1758) and Chinese spot-billed duck (Anas zonorhyncha Swinhoe, 1866), in the core wintering waterbird community in the study area. We evaluated the community variation in richness and distribution and analyzed the relationships between the population and water level, temperature, humidity and precipitation. We recorded 23,556 waterbirds in our surveys; the total number of birds decreased slightly but not significantly during the study period. Among the seven species, a significant decreasing trend with increasing water level was observed only for the grey heron (Ardea cinerea Linnaeus, 1758) during the study period. The waterbirds were mainly observed upstream of Wanzhou county due to its shallow shores and meandering and rapid water in the TGRR. The correlations between the waterbird populations and annual average temperature and humidity were significant. Protected areas should be established in the shallows of upper Wanzhou county in the Yangtze River, and waterbird surveys should be strengthened throughout the TGRR.