Members of the spoon-billed sandpiper survey team look for the bird in Rudong. Chen Liang / China Daily

Besides the sandpiper, they mainly look for another critically endangered wader, Nordmann's Greenshank.

Their five-day survey produced some "amazing records", says Li Jing, coordinator of SBS in China.

At least 140 spoon-billed sandpipers, 1,200 Nordmann's Greenshanks and "internationally important concentrations" of several other species of waterbird as defined by the intergovernmental Ramsar Convention on wetlands, were recorded.

This is the largest number of the fast-declining spoon-billed sandpiper found anywhere in the world since 2008. It is also the largest count of Nordmann's Greenshank.

After molting their breeding plumage (which is colorful) to their wintering plumage (which is gray and dull) in Rudong, the spoon-billed sandpipers become "extremely difficult to find", says Nigel Clark, from the British Trust for Ornithology in the UK. So the actual number of spoon-billed sandpipers in Rudong should be more than the count.

"That means 80-90 percent of the bird's adult population will molt here in Rudong," says the ornithologist.

As for the Nordmann's Greenshank, the estimated world population in 2012 is about 700 to 1,000 birds. "This year's number means the whole population of Nordmann's Greenshank will pass this site in October," he says.

Many of the most important intertidal wetlands along the Jiangsu coast are threatened by continuing reclamation for agricultural and industrial development, Li Jing says.

However, local and provincial authorities now recognize the international importance of the area and announced at a workshop following the survey the creation of a new protected area for spoon-billed sandpiper, together with an additional two shellfish and fishery protected areas.

These sites overlap with most of the wader feeding areas and it is hoped that they will eventually achieve protection at provincial and national level.

"Our surveys confirm the intertidal wetlands of Rudong as the most important remaining stopover site for the spoon-billed sandpiper during its entire 8,000-km long migration route," says Li, who organized the survey and workshop with Christoph Zockler of the SBS Task Force. "Protecting these intertidal wetlands is vital for the sandpiper's survival, and also for the maintenance of the shellfishery and other vital services provided by tidal flats. We urgently need more conservation action in China to prevent SBS and other tidal flat species from going extinct."

The two-day workshop was co-hosted by the Rudong government and the SBS Task Force.