Maintaining shallow waters to maximize the potential of saltpans as foraging habitat for migratory shorebirds along an endangered flyway

The global expansion of human activities has led to a dramatic reduction in natural wetlands. While effectively managed artificial wetlands hold the potential to counteract this decline, there is often a lack of knowledge regarding how to enhance their value for wildlife. To bridge this gap, we studied one of the world's largest saltworks in the Yellow Sea, China. This region has experienced significant natural wetland losses, resulting in marked declines in waterbird populations across the East Asian-Australasian Flyway (EAAF). Our research examined the impact of biotic factors such as prey abundance, and abiotic factors including water depth and management practices of saltpans, on the distribution of foraging shorebirds, as well as other waterbirds. Findings reveal that shorebirds, accounting for 95% of all waterbirds, heavily utilize saltpan evaporation ponds. Although various factors affect the distribution of shorebirds and other waterbirds, water depth and abandoned ponds (with low water depth) emerged as the primary factors. Notably, prey biomass (and abundance) did not exhibit a significant correlation with bird distribution across all shorebirds and other waterbirds, indicating that prey accessibility is more crucial than biomass in determining habitat suitability in these saltpans. Based on these insights, we propose tailored management strategies for the Yellow Sea saltpans that enhance conditions for shorebirds without impeding salt production, including lowering water levels through modifications to pond structures and reducing the volume of water evaporated during each stage of production. These straightforward, bird-friendly strategies provide practical solutions for adapting artificial wetlands to support migratory waterbirds in the EAAF and offer valuable insights for global waterbird conservation.