Waterbird diversity and its landscape associations across seasons and scales: Conservation and management implications for the Yellow River Basin

Waterbird diversity and its landscape drivers along the YRB remain poorly understood across seasons and spatial scales. Waterbird observations from five synchronous surveys conducted between October 2022 and October 2023 were integrated into four seasonal datasets and combined with land-use data to examine diversity–landscape associations across spatial scales from 5 to 50 km. Waterbird diversity was significantly lower in winter than in spring and summer, and lower in the lower reaches compared with the middle and upper reaches. Relationships between landscape structure and waterbird diversity varied by season, scale, and region. Spring diversity was positively linked to PC3 derived from principal component analysis at 10 km (F = 9.273, p < 0.01, estimate = 0.096), implying a beneficial role of grassland–cropland heterogeneity. Summer effects indicated that grassland area, dominance, and impervious-surface aggregation may shape breeding-season diversity, with significant PC3 × region and PC2 × region interactions at 5 and 10 km, respectively (F = 3.951, p < 0.05; F = 3.040, p < 0.05). Autumn relationships showed a positive PC1 effect at 5 km (F = 12.814, p < 0.01, estimate = 0.184) and a significant region × PCA interaction at 50 km (F = 2.961, p < 0.01), suggesting that greater grassland extent and dominance may provide a favorable landscape context for migratory waterbirds. Winter at fine-scale showed that greater grassland availability provided a favorable local context, whereas more complex wetland and barren-land structures corresponded to lower diversity, as supported by contrasting principal component effects at 5 km (PC1: F = 9.143, p < 0.01, estimate = 0.169; PC2: F = 4.796, p < 0.05, estimate = −0.159; PC3: F = 6.266, p < 0.05, estimate = −0.068), whereas broad-scale gradients reflected wetland shape variability and regional landscape heterogeneity. These findings underscore the need for season-specific, multi-scale habitat management to conserve waterbirds across the YRB.