Waterbird diversity and its influencing factors in various types of coastal wetlands in the Bohai Rim region

The coastal wetlands of the Bohai Rim region in China serve as critical habitats for breeding, migratory stopovers, and wintering birds along the East Asian-Australasian Flyway. This study surveyed waterbird diversity across 17 coastal wetlands in the Bohai Rim region from 2018 to 2023 to identify community composition, analyze spatial and temporal patterns, and examine the key factors influencing waterbird diversity across various wetland types. A total of 133 species belonging to 18 families and 8 orders were recorded, with migratory species comprising 85.71% of the total. Scolopacidae, Charadriidae, and Laridae exhibited the highest species richness and abundance, respectively. The number of waterbirds and diversity indices displayed a fluctuating but overall upward trend during the study period. Estuarine wetlands had the highest waterbird diversity, tidal wetlands exhibited the greatest bird density, whereas shallow sea and island wetlands showed comparatively lower diversity and evenness. The primary factors influencing waterbird diversity, ranked by significance, were PM 2.5 concentration, vegetation coverage, macrobenthic biodiversity, regional population density, and temperature. High PM 2.5 concentrations were significantly associated with reduced waterbird diversity, whereas higher vegetation coverage promoted diversity by improving habitat complexity. Macrobenthic biodiversity influenced food web dynamics via predation and competition, leading to a marginally negative impact on waterbird diversity. Regional population density significantly impacted waterbird diversity in island and tidal wetlands, highlighting the necessity of establishing and managing protected areas to sustain waterbird diversity. Additionally, increased precipitation caused by climate change alters wetland water levels, indirectly impacting habitat conditions for waterbirds. Improved wetland management and pollution control are essential for preserving waterbird diversity. This study provides important insights into how air pollution, water pollution, and climate change affect waterbird diversity, emphasizing the importance of integrated management strategies for maintaining coastal wetland ecosystem stability and the health of waterbird communities. • Surveyed 17 coastal wetlands over five years (2018–2023), documenting 133 species and highlighting the region's importance as a migratory stopover. • Estuarine wetlands exhibited the highest waterbird diversity, while tidal wetlands had the highest bird density; shallow sea and island wetlands had lower diversity and evenness. • Air quality (PM 2.5 ), vegetation coverage, and macrobenthic biodiversity significantly influenced waterbird diversity, with PM 2.5 showing negative impacts and vegetation coverage promoting diversity. • Regional population density negatively affected waterbird diversity, particularly in island and tidal wetlands, underscoring the importance of establishing protected areas. • Calls for improved wetland management, pollution control, and dynamic water level management to preserve waterbird diversity amidst environmental pressures.