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Understanding species distribution patterns and what determines them is critical for effective conservation planning and management. In the case of shorebirds migrating along the East Asian‐Australasian Flyway (EAAF), the loss of stopover habitat in the Yellow Sea region is thought to be the primary reason for the precipitous population declines. However, the rates of decline vary considerably among species, and it remains unclear how such differences could arise within a group of closely related species using apparently similar habitats at the same locales. We mapped the spatial distributions of foraging shorebirds, as well as biotic (benthic invertebrates consumed by migrating shorebirds) and abiotic (sediment characteristics) environmental factors, at a key stopover site in eastern China. Five of the six sediment characteristics showed significant spatial variation with respect to distance along the shoreline or distance from the seawall in the same tidal flat. The biomasses of four of the six most abundant benthic invertebrates were concentrated in the upper or middle zones of the tidal flat. The distribution patterns of all three focal shorebird species on the tidal flat were best explained jointly by this heterogeneity of sediment characteristics and invertebrate prey. These results suggest that the loss of tidal flats along the Yellow Sea, which is typically concentrated at the upper and middle zones, may not only reduce the overall amount of staging habitat, but also disproportionately affect the most resource‐rich portions for the birds. Effective conservation of shorebird staging areas along the EAAF and likely elsewhere must consider the subtle habitat heterogeneity that characterizes these tidal flats, prioritizing the protection of those portions richest in food resources, most frequently used by focal bird species, and most vulnerable to anthropogenic threats. Article impact statement: Heterogeneity of tidal flats with respect to biotic and abiotic factors must be considered in shorebird conservation planning. [ABSTRACT FROM AUTHOR]

Simple Summary: Due to the rapid environmental changes in the Seocheon Tidal Flat, South Korea, important staging and wintering sites of the vulnerable Far East Russin population of Swan Goose are threatened. To provide practical information for establishing protection strategies based on Swan Goose behavioral characteristics, we estimated core home range and habitat use patterns over time at the Seocheon Tidal Flat during wintering. Based on the GPS tracking data, the core home range and habitat use characteristics of the Swan Goose differed significantly between daytime and nighttime (Day: 59.9 km2, Night: 40.3 km2, on average, 100% MCP). In addition, our data indicated that Swan Goose has two important overnight resting areas in the Seocheon Tidal Flat, South Korea, namely the Janggu Bay and sand dune areas in Yubu Island. The Seocheon Tidal Flat is an important staging and wintering site for the Far East Russian population of Swan Goose (Anser cygnoides) in the East Asian–Australasian Flyway. However, rapid environmental changes for tourism in this area can threaten the survival of this vulnerable population by hindering sufficient rest and wintering; therefore, establishing protection strategies based on Swan Goose behavioral characteristics is necessary. Here, we estimated Swan Goose core home ranges and habitat use based on GPS tracking data collected at the Seocheon Tidal Flat in South Korea from 2017–2018. The home range of Swan Geese was estimated to be an area from Yubu Island in the south to Janggu Bay in the north; however, the core home range and habitat use characteristics differed significantly between daytime and nighttime (Day: 59.9 km2, Night: 40.3 km2, on average, 100% MCP). During the day (08:00–18:00), Swan Geese mostly spent time resting or feeding on tidal flats, especially those around tidal channels or paddy fields near Janggu Bay, whereas they mostly rested on sand dunes near Yubu Island along with the mudflats at Janggu Bay at night. Our results provide practical information on the habitat use of wintering Swan Geese population over time and indicate that Yubu Island is an important resting place. Hence, these results can contribute to evaluating threats to Swan Geese and establishing management and protection strategies for the Seocheon Tidal Flat, a major wintering site for the Far East Russian population of Swan Geese. [ABSTRACT FROM AUTHOR]

Identifying where and when population 'bottlenecks' occur is critical to the conservation of migratory species, many of which are declining precipitously worldwide. Especially challenging is the evaluation of changes to staging sites. These sites are indispensable links in the migratory cycle but are typically used only briefly.We devised a field‐based approach to assess the quality and carrying capacity of a critical staging site in Nanpu, China, for the declining, migratory Red Knot (Calidris canutus rogersi & C. c. piersmai) during northward migration. The Nanpu tidal flat supports 50,000–100,000 Red Knots annually, and while there, the knots feed almost exclusively on the bivalve Potamocorbula laevis. We simultaneously monitored changes in the abundance of Red Knots and bivalves across this entire staging site in spring 2018.After taking into account potential competition with other shorebird species, we estimated that the Nanpu tidal flat was capable of supporting approximately 1.46–1.70 times the observed level of Red Knot usage of this site, and therefore is operating below, but close to, carrying capacity with respect to food resources for Red Knots. This result suggests that any further habitat loss or degradation at this site could harm the Red Knot population along the entire East Asian‐Australasian Flyway.Synthesis and applications. Quantitative monitoring and evaluation of habitat quality of staging sites are essential to successfully conserve declining migratory species. In particular, researchers and conservation practitioners should incorporate both population size and staging duration to more accurately assess the importance of different sites and to quantify how changes in staging habitat quality may translate into changes in the population sizes of migratory species at both local and global scales. [ABSTRACT FROM AUTHOR]