Seed dispersal by wintering ducks in a coastal wetland of eastern China

Duck species are important vectors for seed dispersal of many plants, contributing significantly to the regeneration of wetland plant communities. However, research on the temporal changes in diet and the dynamics and differences of seed dispersal among different duck species is still limited. In this study, we analyzed the diversity of duck community and the diversity of seeds in the feces of different duck species from December to February for 2022–23 and 2023–24 in the coastal wetland of Dafeng, eastern Jiangsu Province, China. A total of 13 duck species were recorded in the four habitats, of which Spot-billed Ducks (Anas zonorhyncha) and Mallards (A. platyrhynchos) were the most abundant. The diversity and abundance of ducks vary across different habitats, and tidal flat supports the greatest diversity and abundance of ducks. We collected fecal samples from Spot-billed Ducks, Gadwalls (Mareca strepera), Mallards, and Eurasian Teals (A. crecca) in the tidal flat, from which seeds belonging to 7 families, 13 genera and 15 different plant species were obtained. There were significant differences in seed dispersal among the four duck species, which varied with the season. Gadwalls and Common Teals showed more significant diversity in seed dispersal, with their feces containing a greater variety of plant seeds, which is related to their broader dietary range and ecological adaptability. Furthermore, the seasonal variation in the number of seeds per feces reflected the availability of seeds in the habitat and the response of ducks to environmental changes, while variations in seed intake among different duck species may be associated with inter-annual weather condition changes. The results of this study will provide a new perspective for understanding the mechanisms of bird-mediated seed dispersal in coastal wetland and offer preliminary insights for the seed dispersal by Asian ducks.