Excerpt: Living on the Wind
Follow a myriad of migrants on their winged journeys.
This single acre of mud held examples of a dozen different migration strategies. Not far from the Pacific golden-plovers stood five American golden-plovers, close cousins distinguished (with difficulty) by their duller plumage and somewhat longer wings. They also breed in western Alaska and make equally epic trips, but in the opposite direction. First they fly east across Arctic Canada, feasting on its wealth of berries and insects before gathering in the Atlantic Maritime provinces; then they swing south, cutting across the western Atlantic nearly 2,000 miles to South America, eventually ending their trip in the grasslands of Argentina. Joining them on the pampas would be greater yellowlegs, which I had seen earlier in the day along freshwater streams flowing into Izembek Lagoon--graceful sandpipers with steely-gray plumage and colorful, ripe-lemon legs. From the muskeg forests of Alaska and Canada, the yellowlegs spill south each autumn across the hemisphere, but they take an overland route, some stopping as far north as the Pacific Northwest and mid-Atlantic coasts, but others pushing on clear to Patagonia.
Simply cataloging the avian wanderers that pass through western Alaska would be a lengthy chore. Virtually every black brant on earth stops at Izembek in autumn, feeding on the world's most expansive eelgrass beds, before moving out in November for destinations as far away as Mexico. Most of the world's emperor geese and Steller's eiders, the latter a threatened species, congregate at Izembek in the fall; the geese move on to the Aleutians for the winter, but the ducks stay put in the sheltered lagoons.
In Beringia, a naturalist may find Hudsonian godwits bound for Tierra del Fuego and bar-tailed godwits headed for New Zealand; the small greenish songbird known as the Arctic warbler, which migrates to the Philippines, and Wilson's warbler, yellow with a black cap, which flies to Central America. There are fox sparrows and golden-crowned sparrows that winter in Pacific coastal woodlands, and gray-cheeked thrushes that travel to the Amazon. All morning, I had been watching weathers, black-and-white songbirds that look like slim thrushes. They'll join their Siberian brethren and fly to China and India, then continue on to eastern Africa together, while wheateaters from the eastern Arctic swing across Greenland and Iceland to reach western Africa by a European route, embracing the world in a wishbone of movement.
Out on the ocean around Izembek were more migratory wonders. The day before, an Aleutian gale had savaged the region, ripping even protected harbors to foam and fury. But from a sheltered nook overlooking Cold Bay, I had watched dark shapes skimming the waves, gliding on stiff, narrow wings that barely cleared the tops of violent whitecaps, to all appearances blithely unconcerned by the storm. These were shearwaters, fittingly named seabirds that spend virtually their entire lives on the open sea and that are among the world's most accomplished migrants.
This particular species, the short-tailed shearwater, nests on small islands off the south coast of Australia and Tasmania. In April and May, at the conclusion of the breeding season, millions of shearwaters pour rapidly north along the western Pacific rim, taking advantage of the prevailing winds--across Oceania, past Japan, and into the Bering sea a month later, where they enjoy perpetual subarctic daylight and a rich food supply. They remain off Beringia until September, when they head down the American coast and across the central Pacific, again aided by local wind currents. The shearwaters return to Australia by late October or November, when observers along the coast of New South Wales have seen as many as 60,000 an hour going past, a torrent of birds fueled by the bounty of the Bering Sea. A short-tailed shearwater may cover more than 18,000 miles in a single year, carving a vast circuit on the Pacific, aided at each step of the way by the prevailing breeze--and yet they arrive back in Australia within the same eleven-day period each year.
Migrations like this leave us staggered; we are such stodgy, rooted creatures. To think of crossing thousands of miles under our own power is as incomprehensible as jumping to the moon. Yet even the tiniest of birds perform such miracles.
Some days before, four hundred miles to the east, I had been camping along the Alagnak River, a crystalline stream that roars out of the Aluetian Mountains of Katmai National Park. The Alagnak flows through open tundra and sparse spruce forests, its banks wrapped in thickets of alder and stunted birch; several times each day, I saw brown bears lunging into the river for forty-pound king salmon as large and red as fireplugs.
The streamside thickets were full of small birds, streaky and tinged with green--blackpoll warblers, five and a half inches long and weighing barely half an ounce each; you could mail two of them for a single first-class stamp. Warblers are largely a tropical family, either as permanent residents or winter migrants, but the blackpoll is the most northerly of the clan, breeding from western Alaska across the midsection of Canada to Hudson Bay, Labrador, and New England. It is also the most southerly in its wintering grounds, migrating as far as the western Amazon, giving it the longest migration of any North American songbird.