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

Vast flocks of Whimbrels were thought to be a thing of the past, until a wildlife biologist discovered nearly 20,000 of these declining shorebirds on a tiny South Carolina island.

From the Autumn 2021 issue of Living Bird magazine. Subscribe now.

I am waiting on a sandy island along the South Carolina coast, on a late evening in May when the low light has gilded everything around me—the waving cordgrass where Marsh Wrens sing, the beach where plovers and sandpipers scurry, the flocks of Black Skimmers that row by with mothlike wingbeats and peevish calls. I have been told that if I wait here for dark, I will see a miracle…a word I use with careful deliberation.

With dusk, the miracle arrives.

Flocks of Whimbrels appear, a few dozen at first, then by low hundreds, then in such numbers that I have a hard time keeping any sort of count. Drawn shoreward from the distant, marshy horizons, they fly in ragged lines and loose clusters, untidy chevrons of big, strong shorebirds, nut-brown bodies and long, flashing wings, beaks curved like the crescent moon that will appear in the black sky a few hours later. A few circle, calling, but most land without preamble on a wide, flat expanse of over­wash beach on the edge of the island, facing into the wind in dense-packed ranks. More, and more, and still more.

A little before eight o’clock, a huge flock sweeps toward me out of an orange sunset. They move in a wide sheet, high at first and then spilling toward the ground like water flowing down a low hill, bunching and veering en masse to their left, following the beach on which I stand. There are perhaps a thousand of them. Seven-whistle calls ring like old brass sleigh bells. They surge around me like river water parted by a rock; there is a moment of wild mayhem, the air churned by motion and wings, and they are gone.

Whimbrels have, to me, always been the big game of shorebirds—large, pow­erful, wary, usually in small and scattered numbers. Like all of the world’s seven remaining species of curlews, they are in serious decline. In my experience, a big flock is half a dozen or so; seeing 40 or 50 makes for a red-letter day. And when I do encounter a decent-sized flock, I can’t help but mourn the vanished legions of now-extinct Eskimo Curlews.

The Whimbrel spectacle I was expe­riencing on the coast of South Carolina in May 2021, on an ephemeral barrier island known as Deveaux Bank near Charleston, was something few people alive today have ever seen. Whimbrels congregate here for a month or more in spring, pausing in their migration between the coast of South America and the Canadian Arctic, to feed on fiddler crabs in the rich tidal marshes. Some 20,000 Whimbrels gather each night on Deveaux Bank during this migratory stopover, the largest such congregation known anywhere on the planet.

In this age of diminishment, when the rarest thing in nature today is sheer abundance, the Whimbrels of Deveaux seem like a glimpse of a vanished time when the continent surged with great shorebird flocks. This discovery, announced to much fanfare in June by a coalition of partners including the South Carolina Department of Natural Resources and the Cornell Lab of Ornithology, is remarkably good news: a mother lode representing half of the Atlantic flyway population of Whim­brels and a quarter of all the Whimbrels in North America. That first night, I wept to see them—a reaction, I learned, which has been almost universal among those so privileged.

But think of those birds another way, and a panic may begin to rise. The dis­covery at Deveaux is a miracle, yes, but this is the eleventh hour for Whimbrels, a species that has declined by more than half since 1994 on a plummeting trend that shows no signs of reversing. The fact that so many birds gather on this one small island highlights a previously underappreciated facet of Whimbrel biology—and shorebird biology in general—that could reveal a key to any conservation strategy to save them: simply providing these birds a safe place to spend the night.

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.

“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.”

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.”

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.

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.

There is no other Deveaux Bank; it’s a point Sanders, Maina Handmaker, Andy Johnson, Bryan Watts—almost everyone involved in Whimbrel research—made to me again and again. Roost sites safe from predators and disturbance, high enough to stay above the highest tides, are all but nonexistent along this part of the coast.

But what if there were more Deveaux Banks? Given the physical limits to how far a Whimbrel can commute in a day, is it possible to use spoil material from coastal dredging operations to create new roost sites, strategically placed to open up huge new areas for feeding? Some biologists think so.

“You can imagine that if 20,000 [Whimbrels] are focused there at Deveaux, and they have a limited sally distance each day, that we could support a lot more if we had another Deveaux in, say, south Georgia,” Watts said. “There’s a lot of available forage habitat down there that’s currently difficult for the birds to access because there’s no night roost.”

A group of Whimbrel experts headed by Sterling’s boss at Manomet, Brad Winn, is working with the U.S. Army Corps of Engineers and agency partners on a plan to create more shorebird hab­itat when the Intracoastal Waterway is dredged or harbors are deepened, using the spoil material to create habitat for Whimbrels and other birds. Planning for such projects is time-consuming, Sterling cautioned.

“When they have that dredge mate­rial and it’s of sufficient quality, we need to have conversations well enough in advance so that material can be put to other uses, including building habitat,” she said.

Watts also stressed that limiting Whimbrels’ exposure to hunting should be a priority. Conservationists have made progress limiting illegal shooting in Atlantic Canada by the owners of commercial blueberry barrens, who get upset when Whimbrels feed on their crop. Guadeloupe suspended hunting of Whimbrels this year, and on Barbados, hunt clubs have voluntarily instituted no-hunting lists, while the island hunt committee and BirdLife International have established no-hunt preserves. On the other hand, the French-controlled island of Martinique has proposed a shorebird hunting season running nearly seven months and permitting gunners to kill up to 10 Whimbrels each (assum­ing such limits are even enforced). The research Watts and others have done on mortality rates makes it clear that Whimbrels are one of several species, along with Red Knots and Buff-breasted Sandpipers, that simply can’t withstand the added pressure of hunting.

“They just don’t have the population size or demography to sustain it,” he said, insisting that such species should be placed on no-hunt lists.

My last night on Deveaux was a dra­matic one. For seven weeks, Sanders and Handmaker had been struggling to catch Whimbrels to tag and track, but the birds—which are, after all, intensely hunted in many of their wintering areas—had proven almost supernat­urally wary, avoiding the cannon nets and other traps. This night, though, high tide coincided with nightfall and a dark-moon period. There would be no wind and thus little surf, so it was a rare chance to safely land on a small sand­bar beyond Deveaux where most of the Whimbrels had taken to roosting. The team set several mist nets there before sunset, waited for full dark, then man­aged to flush 14 Whimbrels into them.

For once, luck seemed to break Handmaker’s way—until the western horizon began flickering with lightning. The wind rose, the muggy air grew chilly, and radar images on our phones showed massive blobs of yellow, orange, and red moving relentlessly our way. A tiny, exposed sandbar miles out to sea seemed a very bad place to be in a thun­derstorm, but the careful, fiddly work of fitting transmitters on shorebirds couldn’t be rushed. By midnight, having banded, processed, blood-sampled, and tagged just two of the Whimbrels with Handmaker’s GPS loggers, Sanders made the difficult call to release the rest of the birds unmarked. Ten of us rapidly and unceremoniously piled our gear into two open Boston Whalers and made a heart-stopping sprint for shore, the final few miles through lashing rain, wind, and thunder that boomed in endless percussion.

And yet for all that drama, the moments to which my mind mostly keeps returning occurred on my first evening at Deveaux. I stood alone then in the gathering darkness at a far corner of the island. Flat gray clouds clotted the faintly pink sky on the western horizon. Behind me the Earth’s shadow was rising, that half of the sky cold and blue-black, reflected in the blue-black ocean against breakers that smashed white. The Whimbrels still poured through, silhouettes coming from the west in jumbled flocks of a few dozen to maybe a hundred each, hugging the dunes, vanishing into the gloom as soon as they passed me.

In the last vestiges of twilight, a flock of a few dozen Whimbrels appeared right in front of me, at head height, only yards away. Without thinking—and not from any defensive instinct, really for no reason I can now imagine—I threw my left hand high into the air, fingers wide, just as they barreled around and past me in a great rush.

And I felt…something. Perhaps the brush of primary feathers on my finger­tips. Maybe just a gust of the sea wind. Maybe a little of the urgency that carries tens of thousands of birds on slender wings from Venezuela to the Arctic and back, and on this night to a newborn spit of sand on the South Carolina coast.

Whatever it was, I stood, breathing hard, my arm still raised like a benedic­tion, as the night swallowed them.

Writer and migration researcher Scott Weidensaul is the author, most recently, of the New York Times bestseller A World on the Wing: The Global Odyssey of Migratory Birds (W.W. Norton).