A Miracle of Abundance as 20,000 Whimbrel Take Refuge on a Tiny Island

Whimbrels and More. Deveaux Bank is important habitat for more than 50 shorebird and seabird species, including one of the biggest Brown Pelican nesting colonies in the East. Photo by Andy Johnson.

Devaux Bank is a giant horseshoe with its open end facing west, sitting in the mouth of the North Edisto River that nourishes it with sediment. Rimmed on three sides with sugar-sand beaches, the long fingers of cordgrass marsh all but bisect its middle. First noted on charts in the 1920s, it was used as a bombing range in World War II and then wiped out entirely by Hurricane David in 1979. Three years later it reemerged from the waves and began regrowing. Just how big it is today depends on the stage of the tide; figure 250 acres as a good average.

Long recognized as critical bird hab­itat, Deveaux Bank hosts nearly 3,000 nesting pairs of Brown Pelicans, as well as breeding Black Skimmers, American Oystercatchers, Royal and Sandwich Terns, Laughing Gulls, and several spe­cies of herons and egrets—the largest Atlantic Coast colonies for several of these birds. The island is a state bird sanctuary and designated Important Bird Area, with all but two small areas, mostly below the high tide line, closed to the public during the nesting season. It’s been a big part of Felicia Sanders’s professional life for more than 20 years.

Sanders, a lanky wildlife biologist with the South Carolina Department of Natu­ral Resources with sun-bleached hair and an easy smile, has worked on Deveaux Bank since 2001, monitoring the nesting seabirds as well as migrant shorebirds, including as many as 6,000 federally listed Red Knots. She’s intimately familiar with the marsh-rich coast near Charleston, with its seasons, its tides, and its rhythms. Yet for most of those years, she never suspected that Deveaux held another, blockbuster secret.

It started with an annoying mishap in the shallow, challenging waters around Deveaux.

“In 2014 I was taking some DNR vid­eographers to film the pelican colony at dawn. So we got there in the dark, and we got the boat stuck on the back side of the island,” Sanders said. “I saw all these Whimbrel coming off the island, just thousands of them and thousands of other shorebirds, and I realized it was a nocturnal roost for a lot of migratory shorebirds.”

She filed away that surprising obser­vation, too consumed with her other duties to pursue it, but a few years later she got back to the island at night and saw another immense dawn lift-off. She then realized what an extraordinary sight she was witnessing.

Maybe a little too extraordinary; Sand­ers could hardly believe she’d stumbled on thousands upon thousands of Whim­brels, and so perhaps it’s not surprising that she had a hard time convincing some of the experts she contacted that she had really found what she’d found.

“They honestly couldn’t believe the numbers,” she said. But then she reached out to Andy Johnson, a multimedia producer with the Cornell Lab of Orni­thology. Sanders had met Johnson years earlier on a bird survey in Churchill, Manitoba, when he was researching a Cornell undergrad thesis on Whimbrels.

State wildlife biologist Felicia Sanders takes a special pride in the Whimbrel roost on Deveaux Bank, not for her discovery, but for her state. “It’s something special,” she says, “that is maybe nowhere else in the world.” Photo by Andy Johnson.State wildlife biologist Felicia Sanders takes a special pride in the Whimbrel roost on Deveaux Bank, not for her discovery, but for her state. “It’s something special,” she says, “that is maybe nowhere else in the world.” Photo by Andy Johnson.
Andy Johnson met Sanders as a Cornell undergraduate when he was surveying Whimbrels in Churchill, Manitoba. Johnson is now a multimedia producer with the Cornell Lab of Ornithology.Andy Johnson met Sanders as a Cornell undergraduate when he was surveying Whimbrels in Churchill, Manitoba. Johnson is now a multimedia producer with the Cornell Lab of Ornithology.

“He rallied the Cornell troops. I took some cellphone videos, and he’s like, ‘Good enough for me, we’re coming down to document this amazing phe­nomenon,’” Sanders said. “He knew a lot more about Whimbrels than I did, and made me realize it’s something special that is maybe nowhere else in the world.”

South Carolina state wildlife biologist Felicia Sanders led a flotilla of scientists and media members in May 2021 to study and document the massive Whimbrel migratory stopover roosting site on Deveaux Bank. Photo by Andy Johnson.South Carolina state wildlife biologist Felicia Sanders led a flotilla of scientists and media members in May 2021 to study and document the massive Whimbrel migratory stopover roosting site on Deveaux Bank. Photo by Andy Johnson.

In the spring of 2019, Johnson and wildlife cinematographer Matt Aeber­hard spent almost a month at Deveaux, on night-long vigils in photo blinds surrounded by thousands of Whimbrels that they filmed with infrared cameras.

“I keep coming back to those moments when the light has fallen and you’re surrounded by these swirls of birds,” Johnson said. “It’s sensory overload because it’s dark and you can’t see what’s going on, but there’s that elemental sense of sharing that tiny spit of land with the Whimbrels in the mid­dle of their journey, connecting these disparate parts of the hemisphere… it’s the sense that you’re connected to something cosmic and huge, very intimately and directly connected to it.”

Whimbrels flying over Deveaux Bank.

There are two main populations of Whimbrels in North America. The western group breeds from the North­west Territories along the Mackenzie River delta into western Alaska, while the eastern group nests south and west of Hudson Bay. It is these Hudsonian birds, which some experts consider a separate species, that are thought to make up the bulk of the Whimbrels passing through Deveaux in such great numbers each spring. Come autumn, they head south through the Great Lakes to the coast of South Carolina or Georgia, staging together in much smaller numbers than in spring, and then follow the arc of the Bahamas and Antilles to the northeast­ern coast of South America.

That means they’re flying right into the storm-raked region known as Hur­ricane Alley. A recent paper authored by Whimbrel expert Bryan Watts of the Center for Conservation Science showed that 13 of 18 tagged Whimbrels taking this route encountered tropical storms or powerful hurricanes. Many of them were forced to rest and recover on the islands of the Lesser Antilles, where they are vulnerable to hunting. In French-controlled overseas depart­ments such as Guadeloupe and Marti­nique, the largely uncontrolled shooting of shorebirds remains legal; Guadeloupe is even advertised internationally for its shorebird “destination hunts.”

Watts and others have analyzed what’s known of the hunting mortality in the Caribbean and South America and conclude that it alone may account for much of the long decline of eastern Whimbrel numbers, which have dwin­dled steadily since at least the 1970s. The best benchmarks for the eastern population come from an annual Whimbrel count on the Delmarva Pen­insula of Virginia every spring, where between 1994 and 2009 Watts and his colleagues documented a 50% decrease. They recently updated those figures through 2020, and found that the same rate of annual decline continues.

The discovery of the global impor­tance of Deveaux Bank has sparked a belated focus on the importance of nocturnal roosts in general, which may be among the most important, rarest, and least-appreciated resources for long-distance shorebird migrants like Whimbrels. At night, these birds need safe places, far from land predators like raccoons and owls and high enough above the waves that even astronomical peak tides twice each month will not submerge them. Sandbars and newly accreted barrier islands serve perfectly, but they are often swept away by storms, and many dammed and altered river systems no longer provide the sediment to rebuild these ephemeral lands.

“There aren’t that many options for the Whimbrels,” Sanders said. “I go to places where I think Whimbrels would roost, and I realize this site’s got too many predators, that site’s got too many pelicans. A lot of the coast is armored, the rivers are dammed, there aren’t that many choices like there were his­torically for these birds to roost. I think nocturnal roosts are a really big limiting factor for shorebird distribution.”

Adding to the complexity of the issue is the profound personality change, from irascible loners to amiable flockmates, that Whimbrels undergo from day to night. One evening on Deveaux—having just helped Sanders and her team set up a cannon net to catch Whimbrels for fitting with GPS tracking tags—I hun­kered among the dune grass with Abby Sterling, the director of Manomet’s Georgia Bight Shorebird Conservation Initiative. Sterling, Johnson, Aeberhard, and others helped Sanders conduct the first rigorous counts of Whimbrels on Deveaux in 2019, tallying up to 19,485 birds gathered together in a single night.

But she and I watched one Whimbrel with no such desire for companionship. Instead, it fiercely defended a swath of mudflat pocked with the burrows of tasty fiddler crabs, much to my surprise driving away any other Whimbrel that landed there.

“They’re very territorial when they’re feeding, which is weird, because they’re so ridiculously social when they gather in these huge flocks to roost,” Sterling said.

That dichotomy has enormous ram­ifications for Whimbrel conservation. During the day, they spread out across an immense area to forage. Fortunately for the birds, the Carolinas and Georgia together have the largest expanse of saltmarsh on the Atlantic coast, nearly 1 million acres. Just south of Deveaux lies the 350,000-acre ACE Basin Proj­ect, a federal-state-private partnership that protects a vast stretch of especially pristine tidal estuary.

So the Whimbrels have plenty of places to hunt, Sterling explained. But come darkness, they have vanishingly few places where they can safely roost. Surveys along the Georgia and South Carolina coasts have revealed only two other such sites: Little Egg Island in Georgia, and Tomkins Island just across the state line in South Carolina, each holding only 1,000 or 2,000 Whimbrels. Deveaux is not only the largest night roost on the Southeast coast, it is by far the largest known in the world.

Preliminary tracking data, including that from several Whimbrels trapped at Deveaux during my time with the team last spring for research by University of South Carolina PhD student Maina Handmaker, show some birds may be commuting up to 30 miles each way between foraging areas and roost sites. That’s expensive travel. New research from Bryan Watts and his colleagues suggests such daily commutes may cost a Whimbrel up to 20% of its premigra­tory energetic budget, fat it needs for the next leg of its hemispheric journey.

Biologists often talk about the need to study the full-cycle biology of a migratory bird—their annual cycle from nesting to migration to nonbreed­ing grounds and back. But the Deveaux Whimbrels remind us that knowing a bird’s full daily cycle may be just as critical to saving it.

Whimbrels return to roost on Deveaux Island at night. Photo by Andy Johnson.Whimbrels return to roost on Deveaux at night. Photo by Andy Johnson.

In a sense, the discovery at Deveaux was a rediscovery. More than a cen­tury ago, ornithologists and shorebird gunners recognized the huge numbers of Whimbrels passing north along the Southeast coast. In his Life Histories of North American Shorebirds, published in 1929, Arthur Cleveland Bent quoted an acquaintance who said that during peak migration, hundreds of thousands of Whimbrels could be seen in a day. Herbert K. Jobs, another of Bent’s cor­respondents, described exactly the sort of nocturnal roost as Sanders had found at Deveaux, occurring on “several little low islands—mere sand bars” off the South Carolina coast. “I hazard a guess that there are often 10,000 curlews at such a roost each night,” he noted in 1905. “At the first glimmer of day they are off again for the marshes.”

Where Jobs saw coastlines largely empty of people and awash with birds, today the reverse is true. We motored out to Deveaux on Mother’s Day after­noon, with hundreds of boats full of happy holiday-goers cruising the North Edisto and waters off nearby Seabrook Island. A dozen boats were pulled up along the two ends of Deveaux Bank open to the public, picnickers amid a backdrop of wheeling Brown Pelicans and Laughing Gulls nesting in the closed areas just beyond.

“Deveaux just feels like a place back in time, before we changed all these processes that make really important habitat for birds. It’s like this little piece of what it looks like when everything goes right,” Abby Sterling later told me. “But it’s a tricky place, right? There’s a history of people from Rockville using that spot, the local community values that place. It’s used by people and it’s critical for birds.

“[But] all these birds have nowhere else safe to go for the night. There is no other Deveaux Bank.”

Felicia Sanders has spent years cultivating local concern for, and pride in, the welter of nesting birds that populate Deveaux. I saw both emotions expressed repeatedly by area residents who chatted up Sanders when she was readying the DNR boats at the public launch, people telling her about nesting ospreys or oystercatcher sightings. When she explained to one fisherman how important Deveaux was for Whimbrels, he excitedly shared stories of seeing huge flocks come in at dusk.

But Sanders, Sterling, and the team of scientists admitted they have been nervous about making the news of the massive Whimbrel night roost public. Frankly, they seemed less concerned about additional pressure from area residents, who tend to use Deveaux and the waters around it during the day, than from birders and photographers.

“I’m a little more worried about people that may want to come out and see this incredible spectacle,” Sterling said. “The birds come here because it’s safe, it’s remote. If they’re flushed, they literally have no place else to go when the tide is high and it’s dark.”

South Carolina DNR officers patrol the area around Deveaux, but they can’t be there all the time.

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