The Sea Journal of the Korean Society of Oceanography ISSN:1226-2978(Print) 2671-8820(Online) 한국해양학회지 바다

Coastal wetlands serve as transitional zones linking terrestrial and marine ecosystems and provide critical habitats for diverse coastal bird species. However, rapid loss driven by reclamation, development, and climate change has raised global concerns about the decline of coastal bird populations. In this study, we analyzed the community structure and spatial distribution of coastal birds across 35 major coastal wetlands in Korea from 2016 to 2024. A total of 129 species and 579,635 individuals were recorded, with Dunlin Calidris alpina (20.60%) and Black-tailed Gull Larus crassirostris (15.43%) dominant at the species level, and shorebirds (54.30%) and gulls (21.49%) dominant at the taxonomic-group level. Community index patterns revealed strong regional contrasts: the Southern Jeolla region exhibited high species richness, diversity, and evenness with a ‘lognormal-type’ structure, whereas the Jeju region showed a ‘hollow-curve’ pattern driven by a few highly dominant species. NMDS (Non-metric Multidimensional Scaling) and PERMANOVA (Permutational Multivariate Analysis of Variance) analyses demonstrated clear separation of bird communities among the West, South, and East/Jeju coasts, indicating that habitat characteristics at the regional scale, rather than geographic distance alone, shape community structure. By taxonomic group, shorebirds were concentrated in western tidal flats, dabbling ducks dominated southern estuarine and brackish habitats, and gull assemblages were characteristic of the eastern coast. Additionally, 25 of the 35 survey sites (71.43%) met the Internationally Important Site (IIS) thresholds, with a total of 36 species (22 of which were shorebirds) identified as exceeding global population criteria. These findings highlight the high ecological significance of Korean coastal wetlands within the EAAF (East Asian–Australasian Flyway). The spatial patterns identified in this study underscore the need to incorporate both community- and habitat-level considerations when establishing region- and seascape-scale conservation strategies for coastal bird habitat networks.