Spatiotemporal dynamics and conservation priorities of shorebird communities in the Yellow and Bohai Seas

Shorebird populations along the East Asian–Australasian Flyway (EAAF) have declined markedly since the early 2000s, largely because of intertidal habitat loss in the Yellow and Bohai Seas. Using synchronized counts from nine key stopover sites across two periods (2013–2015 and 2019–2021) during spring and autumn migration, we examined spatiotemporal community dynamics using PERMANOVA, ANOSIM, SIMPER, NMDS, and LCBD, and developed a composite site-importance index integrating IUCN threat status, stopover duration, and the 1% flyway population criterion. Overall abundance and species richness increased at most sites in the recent period, particularly in the southern Yellow Sea, whereas northern sites were generally stable or showed slight declines. Community composition showed no significant inter-period shifts, indicating broad temporal stability in site-level assemblages. Clear seasonal contrasts were evident: northern Bohai sites supported higher richness and abundance in spring, whereas autumn assemblages were more concentrated at southern sites and were driven by a small number of dominant species. LCBD analyses indicated declining uniqueness in some northern communities, while several southern sites maintained relatively strong contributions to regional beta diversity. The composite index identified Rudong, Dongying, and Tiaozini as among the highest-priority conservation hotspots, with Tiaozini standing out particularly in recent autumn; however, early-period data for this site were unavailable, precluding direct inter-period comparison. A complementary leave-one-site-out analysis showed that a small number of southern sites disproportionately supported regional abundance, especially in autumn. These findings highlight increasing autumn concentration at southern Yellow Sea stopovers and underscore the need for season-specific conservation. • Quantified β-diversity patterns across nine key Yellow–Bohai stopover sites along the EAAF. • Tested site-specific community uniqueness and contributions to regional compositional variation. • Compared 2013–2015 vs 2019–2021 to evaluate recent changes in communities and site roles. • Revealed stronger reliance on southern Yellow Sea sites during autumn southward migration.