Composition and diversity of waterbirds’ community in the Dafeng River Estuary, Guangxi

The estuary of the Dafeng River in Guangxi, situated along the East Asian-Australasian Flyway, serves as a crucial habitat for a multitude of migratory birds along the coast of the Beibu Gulf. Currently, systematic research on waterbirds at the Dafeng River Estuary remains scarce. Understanding the community structure and diversity of waterbirds in this region is of great significance for the conservation of coastal migratory birds. From January to December 2022, we conducted surveys of waterbird communities in six sampling sites across four habitat types, using the method of sampling sites and direct counting in the Dafeng River Estuary wetlands. The survey recorded a total of 87 waterbird species from 12 families and 7 orders, with a cumulative count of 74 394 individuals. Among these species, four were national first-class protected species, including Spoon-billed Sandpiper(Calidris pygmaea), Spotted Greenshank(Tringa guttifer), Black-faced Spoonbill (Platalea minor) and Saunders's Gull (Saundersilarus saundersi). And eight were national second-class protected species. One globally critically endangered (CR) species, four globally endangered (EN) species, five globally vulnerable (VU) species and eight near threatened (NT) species were observed. The waterbird diversity showed significantly seasonal variation, with more species and numbers of waterbirds in autumn and winter. The dominant species were Black-headed Gull (Chromocephalus ridibundus), Dunlin (Calidris alpina) and the Lesser Sand Plover (Charadrius mongolus). In Dafeng River Estuary, the maximum monthly numbers of Grey Plover(Pluvialis squatarola), Kentish Plover(Charadrius alexandrinus), Lesser Sand Plover and Dunlin were recorded to exceed 1% of the population size along the East Asian-Australasian Flyway, meeting the criteria for an internationally important wetland. The composition of waterbird communities varied in different habitats, with the highest number of recorded waterbird species at 51 in aquaculture ponds and fewest at 21 in farmland. In conclusion, coastal mudflat wetlands along the Dafeng River estuary in Guangxi satisfy the international criteria for significant wetlands, and is an important stopover site and wintering area for migrating waterbirds on the East Asian-Australasian Flyway. Urgent measures are needed to enhance their management and protection.