Fig. 1: Widespread loss of shorebirds across the Yellow Sea.

a Changes in shorebird abundance at 14 sites (the Yangtze River Estuary is the focal study site). The percentage rates of change were estimated based on shorebird surveys during northward migration in an early study period (1996–2005) and a late study period (2013–2014). Also shown is the distribution of tidal wetlands in 1999 (ref. ¹⁹). The background map, made with Natural Earth (https://www.naturalearthdata.com/), is in the public domain. b Number of shorebird species with a decreasing, stable, and increasing population. Two analyses are given: one based on the Yellow Sea survey¹⁸ and the other – Flyway assessment – based on assessments of the global population of all shorebird species that utilize coastal habitats in the Yellow Sea (http://www.birdlife.org). c Changes in the abundance and species richness of shorebirds at the focal study site during northward migration. Data are extracted from annual reports of a nature reserve at the study site (Chongming Dongtan; https://www.dongtan.cn/). Exotic Spartina alterniflora was eradicated since 2015 (shaded area). d Meta-analysis of shorebird predation intensity (left) and crab grazing effects on native plants (right) at different sites (see panel a for locations). Data are shown as means with error bars for 95% confidence interval. n indicates the number of independent sites (for shorebird predation intensity) or tests (for crab grazing effects). Shorebird predation intensity indicates the percentage of tethered crabs eaten by shorebirds within 24 h and should be interpreted mainly as the presence, rather than the absolute natural rate, of shorebird predation. Effect sizes are log response ratios, with negative ones indicating that crabs suppress plant biomass. Data of shorebird predation intensity were tested against zero using a one-sample nonparametric Wilcoxon test (two-sided), and effect sizes of crab grazing were tested using a random-effects model. See “Methods” for further details.