October 8, 2015
As dawn breaks over the Yellow Sea, Jimmy Choi wades barefoot through the receding tide, a tripod and powerful telescope on his back. The best time to spot migratory shorebirds is an hour before and after high tide—at 4:10 a.m. on this late summer day—when they cluster on exposed mudflats. Once his tripod is firmly planted in the mud, Choi, an ecology postdoc at the University of Queensland (UQ), St. Lucia, in Australia, peers through his scope at a group of foraging birds. “I’ve got a spoon-billed sandpiper!” he says, triumphant. He checks a GPS device and records the exact location in a waterproof notebook.
Reddish feathers on its neck and upper breast show that the bird is fresh from its breeding grounds, more than 5000 kilometers away on the Chukchi Peninsula of far northeastern Siberia in Russia. Such sightings are increasingly rare. Scientists counted at most 220 breeding pairs of spoon-billed sandpiper at Russian sites in 2009, down from 1000 pairs spotted in 2000 and a huge drop from the estimated 2000 to 2800 of the 1970s, according to a 2010 Bird Conservation International paper.
The population collapse has landed the spoon-billed sandpiper on the International Union for Conservation of Nature’s critically endangered list. And it is a sign of serious trouble for many other migratory birds that sojourn in the coastal wetlands of the Yellow Sea. Of nearly 500 species using the flyway, more than 50 are endangered or vulnerable. The sandpiper “is like the canary in the coal mine—it’s an early warning of what happens when you remove or disturb the habitat that migratory birds depend upon,” Choi says.
Perhaps nowhere else in the world has the loss of habitat for migratory birds been as sudden and severe as in the Yellow Sea. In just 5 decades, between 50% and 80% of the tidal flats along 4000 kilometers of coastline in China and the Koreas has been lost to development, according to an analysis of satellite and other data by Richard Fuller, an ecologist at UQ St. Lucia, and colleagues published in Austral Ecology in January. The loss affects all migratory birds traveling the East Asian-Australasian Flyway. In Australia, at the southern end of the route, “we’ve seen massive declines in all the shorebirds we’ve studied—many species appear to be on their way to extinction,” Fuller says. Nial Moores, an ornithologist and director of Birds Korea in Busan, calls it “one of the greatest ecological disasters on the planet.”
The Rudong wetlands, about 140 kilometers north of Shanghai, are on the front lines. They are “one of the very few healthy mudflats left,” says Jing Li, founder of the Shanghai-based nongovernmental organization (NGO) SBS in China. But already, a 15-meter-high concrete embankment blocks the tides, creating a stark boundary between now-shrunken mudflats and reclaimed land given over to chemical factories and a fish farm pond. Choi and his team, which includes scientists and volunteers from China, Australia, and the United States, are counting and videotaping birds and gathering other data to document the site’s critical ecological importance. And groups including Li’s NGO are promoting public awareness within China, hoping to spur action to save the Rudong and other Yellow Sea habitats. “We want the central government to make policies to stop this degradation,” Li says, such as rethinking the economic incentives pushing local governments to support coastal development.
The Yellow Sea has outsized importance because of its location near the center of the East Asian-Australasian Flyway, which spans 22 countries and is used by about 50 million migratory birds. “Think about the map of Asia—really the only places these coastal birds can stop [between the Arctic and lower latitudes] are Japan and along the Yellow Sea,” Fuller says. Those waystations are by far the most threatened part of the flyway. Breeding grounds in Siberia remain intact, and financial incentives to stop bird poaching in wintering grounds in Myanmar and Bangladesh are showing positive, if preliminary, results, Choi says.
In the Yellow Sea, however, development shows no sign of abating. “The drastic loss of habitat [in China, the Koreas, and Japan] is the most important issue,” says Hiroyoshi Higuchi, a professor emeritus at the University of Tokyo who studies bird migratory routes. Japan and the Koreas both have a long history of reclaiming wetlands for agricultural and industrial use. In one big blow to the flyway, in 2006, South Korea erased what Moores calls “one of the most important known shorebird sites in the Yellow Sea”—the Saemangeum estuarine tidal flat—by enclosing it with an enormous seawall.
With much of the shoreline in the Koreas and Japan already heavily developed, scientists are focusing on China. Since the early 1990s, seawalls went from lining just 18% of the country’s 18,000-kilometer coastline to 61%, forming “a new great wall,” researchers from China, the United States, and the Netherlands reported in Science last year (21 November 2014, p. 912). They also calculated that reclamation is accelerating. Driven by urbanization and the construction of industrial zones, ports, and other infrastructure, it has surged from 400 square kilometers per year between 2006 and 2010 to a projected 580 square kilometers annually between 2011 and 2020.
Yang Liu, an ecologist at Sun Yat-Sen University, Guangzhou, in China, who studies the nesting survival rate of the Kentish plover, is a witness to the losses. He and his colleagues saw one of their study sites in Bohai Bay, at the northern tip of the Yellow Sea, disappear from one year to the next. “That wetland area was already completely lost,” Yang says.
Upstream development is adding to the toll by cutting off the sediment that rebuilds the coastal wetlands. In the 1950s, the Yangtze River each year added 90 million tons more sediment to Yellow Sea mudflats than was washed away. But during the past 50 years, China has built more than 50,000 dams on the Yangtze watershed, including the massive Three Gorges Dam, completed in 2003. Now, the sediment balance is negative, with the mudflats losing 60 million tons per year, oceanographer Kehui Xu of Louisiana State University, Baton Rouge, and co-authors calculated in 2010 in Global and Planetary Change. Dams along the Yellow River have had a similar effect.
Climate change will also erode habitat, both in the Yellow Sea wetlands and in the birds’ northern breeding grounds. Fuller and colleagues project that rising seas will submerge between 23% and 40% of the flyway’s intertidal habitats within a century. That could cut populations of 10 long distance migratory bird species by 72%, the researchers concluded in a 2013 study published in the Proceedings of the Royal Society B. And as the tree line moves northward in the Arctic, it will encroach on the tundra that the spoon-billed sandpiper and many other shorebirds prefer for nesting, says Hannah Wauchope, a Ph.D. student of Fuller’s who is co-author of a forthcoming paper on climate change impacts on the flyway.
The spoon-billed sandpipepr may be among the first victims of habitat loss in the Yellow Sea. Its unusual beak is adapted for very specific foods and tidal environments, Moores says: estuarine sand flats covered with a thin layer of mud and silt. The beak’s “wide, spoonlike tip is used for pummeling mud to liquefy it—out of which it extracts very small shrimps.” In the past, he adds, “the spoon-billed sandpiper was a top predator in that environment—very effectively adapted.” Now, that specialization could prove its downfall.
Preserving habitat for the spoon-billed sandpiper will benefit all migratory shorebirds, and the impact goes beyond birds. “Wetlands conservation is important for fisheries, for ecosystems services, for providing a buffer against storms, and climate change,” Moores says. A bit of evidence was on display that late-summer morning: As Choi’s team stomped along in gumboots, a dozen local people with sun hats, buckets, and rakes were following the retreating tide searching for crabs and shellfish.
Fuller notes that China has signed several bilateral agreements with key flyway countries to protect migratory species and wetlands. But for now the economic incentives work against conservation. “Local governments can obtain huge profits from selling the use right of land created by coastal reclamation,” Zhijun Ma of Fudan University in Shanghai and his colleagues wrote in their Science perspective.
In June, China’s State Forestry Administration (SFA), which is responsible for wetlands, and the Chicago, Illinois–based nonprofit Paulson Institute, a think tank founded by former U.S. Treasury Secretary Henry Paulson, launched a new Coastal Wetland Conservation Network in Fuzhou, to share best practices and increase the effectiveness of China’s conservation efforts.
“China does not have existing laws or regulations for wetland conservation or protection,” Ma Guangren, director of SFA’s wetland management center, said in a statement issued during the Fuzhou meeting. “Wetlands are currently classified as ‘unused’ land in China and open to development, agriculture, and other uses. Changing this land classification would be a major step forward in improving public awareness of the great importance and value of wetland ecosystem services.”
After meetings with SFA officials, Spike Millington, chief executive of the East Asian-Australasian Flyway Partnership based in Incheon, South Korea, was convinced that Beijing is now taking a greater interest. “But I think the issue is how do you get word out to local government planners,” he says, adding there is a need for real enforcement.
“Probably in the whole flyway, the two most critical sites are Rudong and the Bohai Bay,” Millington adds. “Unless something changes, in 5 or 10 years, they could be gone. There’s not much time.”