Historical changes in the waterbird community of Baiyangdian

Baiyangdian, as the largest freshwater wetland system in North China and a crucial stopover on the East Asian-Australasian Flyway, holds significant ecological value for the waterbird conservation in China and across the flyway. This study systematically reviews the long-term changes in the waterbird community of Baiyangdian over the past century by combining literature research, citizen science data, and field survey results. The final list includes 98 species from 7 orders and 16 families. Historical records show that 40 species were recorded in the 1930—1938, 46 species in the 1958—1964, and 86 species in the 2000—2024, indicating notable changes in the community structure. Anseriformes and Charadriiformes have consistently dominated, maintaining a proportion of 68%—74%. The increase in species numbers may be driven by enhanced survey effort, reduced human disturbance, species recovery, and climate warming. The list includes 10 globally threatened species: Anser cygnoides, Aythya ferina, Aythya baeri, Clangula hyemalis, Oxyura leucocephala, Leucogeranus leucogeranus, Antigone vipio, Grus japonensis, Calidris acuminata, and Ciconia boyciana. Additionally, 6 near-threatened species are recorded: Aythya nyroca, Zapornia paykullii, Vanellus vanellus, Numenius arquata, Limosa limosa, and Pelecanus crispus. The concentrated distribution of these species highlights Baiyangdian′s critical role as a freshwater wetland ecosystem, providing essential habitats for migratory waterbirds that prefer both coastal and inland wetland environments. Given the increasing scarcity of freshwater wetlands in North China, it is recommended to include Baiyangdian within the national park system to enhance its ecological function as a key node in the migratory bird network. This initiative will contribute to improving the protection effectiveness for both threatened and common waterbird species while addressing the ecological demands resulting from the northward shift of bird wintering areas due to climate change.