The sanderling is the white sandpiper or “peep” of summer beaches, the tireless toy bird that runs before the surf. Because of the bold role it plays in its immense surroundings, it is the one sandpiper that most people have noticed. Yet how few notice it at all, and few of the fewer still who recognize it will ever ask themselves why it is there or where it might be going . . . .
—Peter Matthiessen, “The Wind Birds”
I see them first as a faint rippling in the sand, the smooth wet sand left behind as the waves retreat. My beachgoing reverie, nourished in part by the sheen of sunlight on that ribbon of ocean edge, is shaken ever so slightly as that sheen wrinkles an instant before the next wave slides up the beach to erase it. Wading into the water I see a few gray shells tumbling in the surf; my curiosity aroused, I dig into the soft wet sand and lift a handful.
Instantly my hand comes alive: no dull, inert sand here, but a hundred kicking legs, digging into my fingers, tunneling, scratching, desperate to escape. Mole crabs! Emerita talpoida—egg-shaped, sand-colored creatures, not crab-like at all but domed and rounded like miniature VW bugs, perfectly shaped for burrowing in the sand, varying in size from barely visible to almost the size of a quarter, “living in the turmoil of broken waves on sandy beaches, moving up and down the beach with the tide, and . . . feeding on organic debris caught by feathery antenna,” as K. L. Gosner so aptly summarizes this odd life in his Field Guide to the Atlantic Seashore. With dozens of mole crabs in each square foot of sand, filtering each retreating wave with “feathery antenna,” no wonder the sand wrinkles and winks in the sun.
It’s alive . . .
One of the unbroken rules of nature is that protein in abundance will be used. I drop my handful of mole crabs, see them disappear in a flash—scrambling gratefully back into the sand—and look ahead. A warm August beach stretches into the distance, holding just a few human swimmers and clusters of small birds, all seemingly chasing the waves. But the birds look more purposeful, more intent. I lift binoculars and watch. Their legs spinning beneath them, these small white sandpipers work the edge of the surf with urgency and precision, staying just above the breaking waves, darting down as a wave retreats, fast beaks probing the wet sand like sewing machines, zipping back up ahead of foam and water. Not one gets drenched, barely wet even except for feet and legs, and from time to time one emerges with a smooth gray pebble in its beak, or so it seems. But I know better now, especially when I see that pebble worried in the beak, then swallowed fast and furtively before the chase resumes.
Who are they, these diminutive white shorebirds that materialize suddenly each July and August along Atlantic beaches to glut on mole crabs, only to disappear—most of them—with the first cold winds of fall? What is the world their eye takes in? Sanderlings (Calidris alba) are among the most widespread of sandpipers, a group noted for spanning the globe in migration. Here in North America, the species breeds on high arctic tundra from the Alaskan coastal plain across an immense sweep of remote northern Canadian islands to Greenland. From there, seeking similar barren tundra, they scatter east, circling back around the northern extremes through Spitsbergen (Norway), Russia (Taymyr Peninsula, Severnaya Zemlya), and the Siberian arctic coast.
Summer is brief at these remote latitudes. By early June, when Sanderlings arrive to court and lay eggs, daylight is constant but snowstorms are common, and the ground is just begging to thaw. It’s a steely-gray world, wet and raw with rare bursts of sunlight and color. A vast open world of small tarns, of lichens and moss and dwarf willows that grow in one hundred years no taller than a hands-breadth, no thicker than a pencil. In parts of the Sanderling’s Canadian arctic, Musk-oxen ramble in small herds across these tundra plains, grazing willows and lichens; strange Pleistocene relicts, “the smoldering embers of a fire that had refused to go out,” as the biologist/painter George Sutton described these shaggy beasts. Wolves dig dens in sandy eskers, and jaegers—dark, hawk-like gulls—hunt lemmings and small birds with the relentless efficiency of arrows launched from crossbows.
Sanderlings touch down in this world, fresh from spring beaches of New Jersey and California, Hudson Bay and Saskatchewan—2,000-4,000 kilometers non-stop in two to three days—and are instantly at home. Their first imperative is to restore body reserves, fat and muscle burned in the long migration up from temperate latitudes. It is these reserves that will help produce eggs, the chief measure of success in the sanderling’s world. To the human eye, food seems non-existent in this half-frozen tundra, but this bird is closer to the ground and far better initiated in the secrets of mud than we are. Here sanderlings find small worms and the larvae of midges and flies that will hatch in the infinite billions a few weeks later, with the first touches of warm sun. Slowly the birds regain weight. Internally they transform, losing flight muscle but gaining in gut and liver and other organs that process food. Courtship blossoms, with males fluttering slowly over the tundra like enormous butterflies, uttering odd frog-like calls over and over for minutes on end. Females, waiting below, appear satisfied with this; fertilized eggs emerge soon after, hidden in ground nests camouflaged among the lichens. By early July chicks hatch and almost immediately follow a parent out into the boundless arctic plain, tiny puffs of down on twig-like legs. They seem much too fragile to survive, all odds against them, but in reality are tough, resourceful, and alert to the faintest stir of insect life which in all its abundance will fuel their quick growth.
It is these birds—parent and chick—that I see a month or two later on the beaches of southern New England. Fresh from the world of dwarf willows and musk-oxen (I could be the first human they’ve seen—a humbling thought), they appear completely at home in their new habitat, gorging on mole crabs, building fat and muscle to power non-stop flights to South America. At dusk on clear August evenings with fresh northwest winds, I see them lift from the beach in restless flight, circling back in unison to feed briefly before jumping off again. Soon, I know, they will leave for good. Bermuda radars aligned to track bird migration show pulses of shorebirds moving high and fast over that island in late summer, at altitudes of one to two kilometers, traveling SSE. Sanderlings are among them. These are the ultra-marathoners among birds, burning twenty to thirty percent of their body mass in single flights of sixty to eighty hours, Cape Cod or New Jersey or the Carolinas to Venezuela or the Guianas or Colombia. They drop exhausted onto the mud beaches of northern South America, and sleep almost instantly, waking to feed voraciously in a few hours.
In a week or two they regain mass and strength. Some remain there all winter, roosting in small flocks along the edges of mangroves and moving out onto the hot wide beaches to feed at low tide. Others push south and east, flying another 3,000-4,000 kilometers over the rainforests of Brazil to the beaches of Patagonia, where tides of five to ten meters expose vast mudflats that teem with marine invertebrates. Who knows why some sanderlings travel on such distances, out of the tropics, while others stay. We do know that in temperate Patagonia they feed well and stay fat, alongside a few other arctic shorebirds, while southern right whales mate and give birth just a few hundred meters offshore. It’s a rich world there. But by mid-April sanderlings are restless again, pushing north along many of the same routes that brought them south in fall. The Atlantic coast provides brief glimpses of them in May, especially in areas where food is abundant, but they are hurrying now, with the urgency of breeding upon them.
As long as mole crabs remain along my home beaches—and I suspect they won’t become the next sushi delicacy—I’ll expect sanderlings to return each summer, at least until the ice caps melt. Food is a powerful draw, especially once breeding is over. While it’s reassuring to see those restless flocks reappear each July, reminding me that sand I once considered lifeless is not, my world feels small in the presence of these birds. But maybe less small now. Those small black eyes, searching the beach for flickers of crab antennae, have seen worlds I can reach at least in dreams: shiny-haired musk-oxen in arctic sun; Caribbean skies on moonlit nights, above the clouds; Patagonian mud.