Flyway-Scale Assessment of Habitat Suitability and Key Environmental Drivers for Waterbirds in Southern China.

Climate change and anthropogenic activities have caused widespread loss and degradation of waterbird habitats, posing a critical global conservation challenge. This study focuses on eastern and southern China, specifically the area south of the 800 mm isohyet, and examines 47 waterbird species. Using the MaxEnt species distribution model, we integrated multi-source environmental variables-including climate, topography, vegetation, land use, and population density-to evaluate the habitat suitability of different ecological groups and identify spatial gaps in the current protection system. The results reveal a clear coastal-to-inland gradient in the distribution of suitable habitats, with high-suitability hotspots concentrated in coastal regions and radiating inland along major river systems. Distinct ecological groups respond differently to environmental factors: NDVI and DEM were identified as key environmental factors for gulls and shorebird, which prefer low-elevation, sparsely vegetated open habitats, while herons and large wading birds are more strongly associated with densely vegetated landscapes. Some groups, such as herons, show broader ecological adaptability, whereas shorebird tend to rely on more specialized habitat types. Spatial overlay analysis indicates a significant mismatch between existing nature reserves and high-suitability areas, with particularly low protection coverage in southern and southwestern regions, highlighting the need for urgent ecological intervention. Our study reveals structural spatial deficiencies in current waterbird habitat conservation efforts and emphasizes the need for landscape-scale conservation strategies, including wetland restoration, habitat corridor planning, and reserve network optimization, to improve the capacity of protected areas to support waterbird diversity and migratory connectivity. The findings provide valuable data support and spatial planning recommendations for future conservation management.