Despite interstates and jet travel, bullet trains and space shuttles, we remain a species awed by distance. Perhaps that's why we find so remarkable the idea of migration – the realization that wild creatures vault the globe on muscle power and instinct, and render distance itself nearly meaningless.
For migratory birds, travel is a nearly continuous state, and the miles that unreel behind them stagger us – all the more so when the traveler is just a wisp of a thing like the white-rumped sandpiper, a bird weighing barely an ounce and a half that makes one of the longest migrations in the Western Hemisphere.
Each year, tens of thousands of these small, sandy-brown shorebirds trade between the highest latitudes of Arctic Canada and Alaska's North Slope, where they breed, and the southernmost tip of South America. The simple fact that a tiny bird will travel 18,000 miles in a single year is remarkable enough, but the white-rumped sandpiper accomplishes this feat in a handful of nonstop leaps that each span thousands of miles.
From the Arctic the birds gather along the Canadian Maritime coast, then fly 3,000 miles down the western Atlantic to the northeastern coast of South America, to Venezuela and its smaller neighbors – a transit of three or four days, flying in the oxygen-poor air 15,000 feet up. From here they continue to push south across the Amazon Basin to the vast tidal flats of Patagonia and Tierra del Fuego, where for several months they enjoy the long days and abundant food of the austral summer.
A few months later, though, the shortening days of a waning summer prod the sandpipers into the air again. They leapfrog first to southern Brazil, where they feed voraciously on tiny invertebrates and lay on great stores of fat - filling their tanks, as it were, for the ordeal ahead. Several days of continuous flight carry them across the wide bulge of the continent. They quickly refuel on the coast of Venezuela or Surinam, then cross the Caribbean and Gulf of Mexico to the Great Plains, again without pausing along the way to feed, drink or rest. Finally, from their staging grounds on the fecund prairie marshes of Kansas, they make one last, 2,000-mile surge north, returning to the Arctic in late May while the tundra is still a frigid patchwork of snow and ice.
I can think of no more perfect symbol of the interconnectedness of wildlands across the Western Hemisphere – and the pressing need to bind up that fraying patchwork–than this small sandpiper. Each year by its movements, it ties together the lagoons of Tierra del Fuego with the shortgrass prairies of the Buffalo Commons, the cold, damp tundra of the Arctic National Wildlife Refuge with the steamy, mangrove-lined coast of Surinam. Like all migrants, shifting across the globe like the seasons themselves, they are the very definition of connection.
It is tempting to think that migratory birds, with the wind at their command and a world spread beneath their wings, would be the creatures least susceptible to humankind's machinations–able to simply move to greener pastures should the need arise. In fact, the opposite is true. Long-distance migration almost always depends on an exquisite convergence of time, place and resources. The white-rumped sandpiper depends upon a seasonal, short-lived explosion of food at almost all of its stops–the bloom of marine invertebrates along the northeastern South American coast in September, for example, and the springtime glut of midge larvae in the Cheyenne Bottoms wetlands in Kansas, where a famished bird may find 50 of the wriggling, nutritious insects in each square inch of mud. When migration routes stretch across tens of thousands of miles and are delicately balanced in time and place, there is no margin for error or loss.
Once, in our ignorance, we believed that to save migratory birds we had only to safeguard their nesting grounds and wintering ranges. But at last we realize that preserving migration means saving, in its full bounty, the hemispheric web of unique habitats on which these birds utterly depend while on the move. Break a link, you lose the chain.
That's exactly what's happening on the East Coast. Red knots, which, like the white-rumped sandpipers, move between Patagonia and the Arctic, descend each May upon the Delaware Bay to feed on the eggs of spawning horseshoe crabs, receiving a critical boost in their annual migration. Or at least, they used to. Overharvesting by commercial fishermen has gutted crab populations by four-fifths since 1990, and thus greatly reduced the eggs available to the famished knots. Few now gain the fat reserves they need to reach the Arctic and successfully breed, and the number of red knots that migrate through Delaware Bay has crashed from 50,000 a few years ago to just 32,000 last spring–of which, scientists estimated, only about 5,300 made it to the Arctic.
The white-rumped sandpiper has avoided such a fate–for now. But its similar dependence on a few, widely scattered way stations is cause for concern. Not long ago, for instance, plans were narrowly averted for industrial-scale hog farming around the fringe of Cheyenne Bottoms, and with it the threat of depleted aquifers and polluted surface water that might have harmed the marsh on which the species depends so completely each spring.
For millions of years, migratory birds stitched the world together with nothing more than sinew and instinct. But no longer. Now they can survive only if we look beyond borders to safeguard a world as seamless and interconnected as the one that a sandpiper knows, as it leaps once more into the sky on flashing wings.