Different Diets in the Same Habitat: How Food Resource Distribution Shapes the Foraging Preferences of Shorebirds in Hangzhou Bay.

The Hangzhou Bay wetland is a crucial stopover site along the East Asian-Australasian Flyway. However, as wetland areas decrease and environmental changes occur, waterbirds have to adjust their dietary strategies to adapt to the available resources. In this study, the diet composition of 11 waders in Hangzhou Bay, China, was assessed via stable isotope analysis technology. The results showed that Gastropoda, which were at the lowest trophic level of five food sources, dominated the diet of shorebirds due to their large number and easy capture, with an average contribution rate of 32.7%. Numenius madagascariensis, Numenius phaeopus, Arenaria interpres, and Anarhynchus leschenaultii showed a relatively "specialized" foraging preference for Gastropoda, with a contribution rate of more than 35%. Other waders showed a more balanced foraging strategy, distributing their feeding more evenly among the five benthic taxa. Foraging preference is not only affected by food supply but also by the physical conditions and survival strategies of waders. For example, the curlews use their slender beaks to probe deep in the sediment, while plovers rely on visual detection to capture prey exposed on the surface of the mudflat. This study highlights the ecological plasticity of shorebird food utilization and emphasizes the importance of optimizing benthic community structure and increasing the supply of highly nutritious food for effective habitat management. These findings provide valuable insights into wetland restoration and shorebird conservation.