A biological bottleneck
The Yancheng Coastal Wetlands are the largest single patch of intertidal mudflats on the planet. This vast habitat is a refueling station on the East Asian-Australasian Flyway (EAAF), a migration corridor for tens of millions of birds. The wetlands annually host around 3 million migratory birds. For some species, the area is essential. More than half the world's population of the endangered Nordmann's Greenshank (Tringa guttifer) and the critically endangered Spoon-billed Sandpiper (Calidris pygmaea) depend on this specific site to rest and feed during their journeys.
The Spoon-billed Sandpiper, a bird smaller than a sparrow with a uniquely shaped bill, has a global adult population estimated at fewer than 1,000 individuals. These birds travel over 8,000 kilometers from their Arctic breeding grounds in Russia to wintering sites in Southeast Asia. They spend two to three months at Yancheng to molt and build up fat reserves for the next leg of their flight. Similarly, surveys have counted over 1,194 Nordmann's Greenshanks at Yancheng's Tiaozini mudflats, leading to an upward revision of the species' entire global population to between 1,500 and 2,000. The concentration of such a large percentage of these species' populations in one place makes the ecosystem's health a matter of global conservation importance.
Shaped by rivers and tides
The wetlands' existence is a direct result of geology and hydrology. For centuries, the Yellow and Yangtze rivers deposited enormous quantities of sediment into the Yellow Sea. This process created a massive system of sand ridges and the most extensive tidal flats in the world. The coastline here stretches for 582 kilometers. The mudflats are not static; they are a dynamic environment, constantly reshaped by the tides, which creates a rich habitat for the benthic invertebrates that shorebirds feed on.
This unique landscape was inscribed as a UNESCO World Heritage site in 2019. The protected area covers over 188,000 hectares and includes a variety of habitats from salt marshes to reed beds. The wetlands are also home to other significant wildlife. The area hosts the world's largest wild population of Père David's deer, or Milu (Elaphurus davidianus). This species was extinct in the wild in China until a herd was reintroduced from the United Kingdom in 1986. Today, the population in the Dafeng Milu National Nature Reserve has grown to over 8,500. The wetlands also provide the largest wintering ground for the red-crowned crane (Grus japonensis), with hundreds arriving each year.