Almost 80 percent of the world's Nordman's greenshanks, another shorebird, use the Tiaozini mudflats as a break during their migration. At least 40 percent of China's wild red-crowned cranes, or more than 200 birds, winter at the Yancheng Rare Birds National Nature Reserve.

A total of 17 species of endangered migratory birds depend on the coastal wetlands to complete their migration."Our wetlands are a 'gas station' for migratory birds," Wu said."They are vital for their survival."

After the bidding success, Wu said Yancheng drafted its three-year (2019-21) plan for sustainable development of the heritage site.

A wetland research institute and a museum are being built; ecotourism projects have been launched; some reclaimed land for economic use will be returned to nature or left for restoration; and an international wetland conference and a bird race will be held annually.

Yu, from the nature resources and planning bureau, said regulations on Yellow Sea wetland conservation, approved by the authorities in Jiangsu, have been implemented since Sept 1. "This provides legal support for our management of the heritage site," he added.

In Jinggang township, the local government is spending about 60 million yuan on a project to return fish ponds to the wetlands. As a result Zhu, the consultant, is busy with his work persuading fishermen to return their ponds to nature.

He said that this is not too difficult, because the fishermen know the land they return will be used for conservation, not for any other economic development projects.

"Conservation suits them," Zhu said. "If they knew the land would be used for a chemical plant, believe me, the fishermen could turn very nasty."