Rare Spoon-Billed Sandpipers Flock Back to China's Tiaozini Wetland

A Ten-Year Return Opens China's Autumn Migration Season

As autumn migration gets under way across East Asia, Jiangsu's Tiaozini Wetland is welcoming back the spoon-billed sandpiper, one of the rarest shorebirds on the planet. CGTN Global Watch reported on August 25 that a spoon-billed sandpiper bearing an "HU" leg tag has returned to the mudflats of Dongtai, the same individual first recorded there a decade ago. The wetland has also logged a greater yellowlegs, a North American shorebird documented in China for the first time. With millions of migratory birds now stopping at Tiaozini each year to rest, molt and spend the winter, the site has become a bellwether for the health of the East Asian-Australasian Flyway.

The 'HU' Flag: One Bird's Ten-Year Journey

The return of the HU-tagged bird is the emotional center of this year's first migration wave. Color-flagged leg tags are the standard tool scientists use to track shorebirds across international borders, and each code tells a story. A bird recorded at Tiaozini in 2016 and seen again at the same wetland in 2026 has survived a decade of round trips that can span more than 15,000 kilometers, from Arctic breeding grounds in Chukotka to wintering sites in Southeast Asia.

For conservationists, the sighting is more than a feel-good reunion. Site fidelity of this kind is a measurable signal that Tiaozini remains a reliable refueling station, and that the bird itself has navigated the hazards of the flyway, from habitat loss at coastal stopovers to the risk of entanglement in mist nets used for food in some wintering regions. Each returning individual is a small data point in the effort to stabilize a species whose global population is counted in hundreds, not thousands.

The Rarest Shorebird on Earth

The spoon-billed sandpiper, Calidris pygmaea, is a fist-sized wader of roughly 14 to 16 centimeters, named for its black, spatula-shaped bill that it sweeps through mud and shallow water to catch larvae and invertebrates. The International Union for Conservation of Nature listed the species as endangered in 2004 and upgraded it to critically endangered in 2008.

The numbers explain the alarm. By 2009, the population had slipped to an estimated 200 breeding pairs. A 2016 assessment put the global population at between 240 and 456 mature individuals, with roughly 100 pairs capable of breeding. Researchers estimate the species has declined by about 90 percent since 2000, driven by the loss of tidal flats along the Yellow Sea, disturbance at wintering grounds, and, in places, the trapping of shorebirds for food. The bird breeds only in the far northeast of Russia and winters primarily in Myanmar, Bangladesh and southern China, making every link in its migration chain critical to survival.

Tiaozini: A Heritage Coastline for Millions of Wings

Tiaozini sits at the heart of the Migratory Bird Sanctuaries along the Coast of Yellow Sea-Bohai Gulf, which China had inscribed as a UNESCO World Heritage site by 2019. The mudflats of Dongtai, part of Yancheng city in Jiangsu Province, were among the last additions to the heritage bid, after research showed they hosted the largest concentrations of spoon-billed sandpipers recorded anywhere in China. The species was first documented at Tiaozini and the neighboring Dongtai-Rudong flats in 2008.

The site's importance has grown with its protection. Each autumn, shorebirds make a stopover of up to three months at the Tiaozini mudflats, arriving after nonstop flights across the Yellow Sea to feed and put on fat for the next leg of the journey. Wetland restoration and the removal of threats such as reclamation have turned the area into a staging ground for millions of birds each year, including Nordmann's greenshank, the black-faced spoonbill and the Dalmatian pelican, alongside the spoon-billed sandpiper.

Why mudflats matter so much comes down to the food web they hide. The intertidal zone of the Jiangsu coast is dense with polychaete worms, small crustaceans and mollusks, the fuel that powers a shorebird's migration. Birds time their arrival to the tidal cycle, feeding frantically in the hours when the flats are exposed. The 2019 World Heritage inscription recognized this productivity as a global asset: the sanctuaries along the Yellow Sea-Bohai coast are now protected as a serial property stretching across China's eastern seaboard, with Tiaozini as its scientific anchor.

Japan Sits on the Same Migration Chain

For readers in Tokyo, the Tiaozini story is not a distant one. The East Asian-Australasian Flyway, the corridor these birds follow, passes directly through the Japanese archipelago. Tidal flats at the northern end of the Ariake Sea, including the Ramsar-designated Higashiyoka-higata in Saga Prefecture, and the mudflats of the Yatsushiro Sea serve as stopover and wintering sites for the same migratory waterbirds that pause in Jiangsu.

Japanese scientists have documented the fragility of these links. A study published in Estuarine, Coastal and Shelf Science in 2026 examined seventy years of changes in stopover habitats for spoon-billed sandpipers across the Japanese archipelago, tracing how natural wetlands, sandy beaches and artificial wetlands have shifted under coastal development. Japan is a partner in the East Asian-Australasian Flyway Partnership, which counts 42 members including 18 national governments, and Japanese research institutions have contributed to the international recovery effort. The wider picture is sobering: across the region, roughly 65 percent of Yellow Sea mudflats have been lost, and Japan's shorebird populations have fallen by about half, putting the squeeze on every species that depends on the same tidal flats.

Japan also carries its own cautionary history. The construction of the Isahaya Bay reclamation dike in Kyushu in the 1990s, built behind promises of flood control and farmland, silted up one of the region's richest tidal flats and became a symbol of what mudflat loss does to migratory birds. Conservation groups and local governments have since pushed for tidal-flat restoration and for Ramsar protection of surviving wetlands such as Higashiyoka-higata, where community volunteers now count returning shorebirds each season. That experience makes Japanese ornithologists attentive readers of the Tiaozini results, which show what protection, rather than reclamation, can preserve.

Conservation Gains and a First-Time Visitor

The Tiaozini sightings this week come amid cautious signs of progress. The international recovery effort, coordinated through the EAAFP Spoon-billed Sandpiper Task Force and an updated Single Species Action Plan covering 2025 to 2035, has combined head-starting programs at the breeding grounds with protection along the flyway. Captive breeding and head-starting, in which chicks are raised in safety before release, have improved fledgling survival rates and helped slow the slide toward extinction.

The appearance of a greater yellowlegs, a species normally found in North America, underscores how much Tiaozini has become a magnet for rare vagrants as well as regular migrants. For Chinese conservation authorities, the first national record is a badge of the wetland's restored health; for ornithologists, it is a reminder that protected mudflats serve as a safety net for birds far beyond the species they were designed to save.

What to Watch For

The autumn migration season runs through October, and monitoring teams at Tiaozini will be watching for more tagged individuals from the breeding grounds, including birds marked in Kamchatka as part of the international program. Their routes and timing will feed into the next round of the Single Species Action Plan, and into decisions about where else along the coast needs protection.

Beyond the data, the season is a test of cross-border cooperation. Flyway meetings under the East Asian-Australasian Flyway Partnership bring Chinese, Japanese, Russian and Southeast Asian scientists to the same table each year, and the spoon-billed sandpiper has a record of outlasting the political weather around it. Japanese tracking data and Chinese wetland management are complementary halves of the same conservation ledger, and the return of the HU-tagged bird is a reminder that both are needed.

For Japan, the season is an opportunity to strengthen the quiet, practical cooperation that keeps the flyway open, from shared tracking data to coordinated habitat protection across the Ariake Sea and the Jiangsu coast. The spoon-billed sandpiper is too small to command headlines, but its ten-year return to one stretch of mudflat says something larger: that a single protected wetland, maintained across borders and decades, can hold a species to life.

By Kenji Tanaka, Staff Writer

This article was produced with AI-assisted research and editorial support. Sources: CGTN Global Watch, IUCN Red List, East Asian-Australasian Flyway Partnership.