The immortal cranes call, their cries sound from afar, their thoughts circle upward into distant skies. Below, on the autumn rivers, stands a man, above him the bright moon. The man wanders aimless, trailing after the endless Milky Way. The wind blows past him. I, too, thinks the man, would like to be utterly free.

--Jiang Yi Ning

That cranes may journey at such altitudes, disappearing from the sight of earthbound mortals, may account for their near-sacred place in the earliest legends of the world as messengers and harbingers of highest heaven. In Cree Indian legend, Crane carries Rabbit to the moon. Aesop extols the crane's singular ability "to rise above the clouds into endless space, and survey the wonders of the heavens, as well as of the earth beneath, with its seas, lakes, and rivers, as far as the eye can reach," and Homer and Aristotle comment on great crane migrations. Every land where they appear has tales and myths about the cranes, which since ancient times have represented longevity and good fortune, harmony and fidelity. Heaven-bound ancients are commonly depicted riding on a crane, or assuming the crane's majestic form for their arrival in the clouds of immortality.

The larger cranes, over five feet tall, with broad strong wings eight feet in span, appear well capable of bearing aloft a wispy old-time sage. The cranes are the greatest of the flying birds and, to my mind, the most stirring, not less so because the horn notes of their voices, like clarion calls out of the farthest skies, summon our attention to our own swift passage on this precious earth. Perhaps more than any other living creatures, they evoke the retreating wilderness, the vanishing horizons of clean water, earth, and air upon which their species -- and ours, too, though we learn it very late -- must ultimately depend for survival.

In the large taxonomic order known as Gruiformes, the odd and elastic suborder Grues includes cranes and their closest relatives, the New World limpkins and trumpeters, and also the cosmopolitan jacanas, rails, gallinules, and coots; it does not include the smaller storks and herons with which they were traditionally grouped on the basis of common wading habits and similarities of rostra, bills, and feet. In 1735 Carl von Linné, or Linnaeus, in his Systema Naturae named the Eurasian or common crane Ardea grus or "crane heron," and in the nineteenth century Audubon would portray a heron as the "little blue crane." Herons were commonly called cranes in Ireland, Scotland, and South America, where no cranes occur, and also in Australia (where the true crane was known, oddly, as "the native companion" because of its close association with the Aborigines). Even in flight and at a distance, cranes look nothing like herons, since cranes fly with neck outstretched rather than curved back onto the shoulders, while storks in flight display broad tails, which all cranes lack. (Crane tails are small and very short, a deficiency obscured by long loose feathers of the inner wing -- the tertials, highly modified to form erect, handsome "bustles" or long trailing plumes when the bird folds its wings upon alighting. Otherwise this bird's extremities -- bill, neck, legs, and toes -- are unusually long.) Furthermore, crane voices with their wild, rolling r are far more musical than the strangled squawks of storks and herons.

Cranes stand straight and erect with bodies parallel to the ground in the manner of ostriches. The hind toe or hallux, elevated like a cockspur, is vestigial in all but the two crowned cranes of the genus Balearica, whose longer hind toe may serve for balance in the perching habit, one of several that distinguish the "primitive" Balearica from modern or "typical" cranes of the genus Grus -- primitive in the sense that in its anatomy and behavior, Balearica is closer to the ancestral form. Another is the fully feathered head, which crowned cranes share with the demoiselle and blue cranes of the genus Anthropoides. In all other cranes, the head is ornamented with a bare area of rough red comb or skin -- bright crimson when the blood is up during the breeding season -- located somewhere on the crown in most of the migratory northern cranes and in varying areas of the face and upper neck in the mostly nonmigratory southern species. (Among the latter, the sarus, brolga, and wattled cranes are additionally adorned with bald greenish brows.) Though the female tends to be smaller, the sexes of all cranes are otherwise indistinguishable when not interacting in pair bonding, courtship, and mating.

The brown coast of Alaska, falling away in the bright mists, gives way to rotted pack ice and the rough gray shallow seas of the vanished land bridge between continents, fifty miles across. Cold sea air over the North Pacific numbs the bright red skin on the sandhill's crown; the long stiff wings creak on the wind. "The flight of cranes, the way they form letters" was noted by the Roman poet Hyginus, among other early observers. Like wild geese, cranes often travel in V formation, presumably having learned -- after millions of miles and long millenniums of buffeting by the great winds -- the aerodynamic limits of formations in the shape of B or H.

The Arctic distances flown at high altitudes by these dauntless creatures humble the seat-bound traveler on Air Alaska. Peering outward from my plastic aerie over the firmament of wind and light, mightily stirred by the unmarred emptiness of land and sea beneath, I could know with Goethe's Faust how "it is inborn in every man that his feeling should press upward and forward" when "over precipitous fir-clad heights the eagle floats with wings outspread, or over flatlands, over seas, the crane sweeps onward toward its home" -- in German, Heimgang or "home going," the return to the lost paradise at the source of all man's yearnings.

Off the aircraft wing rises Nunivak Island, where thirty years ago I was a member of an expedition that captured ten burly musk-ox calves, the nucleus of a domestic hero to be raised in Fairbanks and turned over to the Inupiaq people in an effort to stabilize their economy. On Nunivak, according to my notes from that expedition, "cranes on long black-fingered wings bugled sadly across the wind" -- among the many far-flung sandhills which have brightened fine days in the field across all of North America, from Alaska to the northern Everglades.

Soon the islands known as the Diomedes -- one in the New World, one in the Old -- loom in northern mists, then Cape Dezhnev and the barrens of Chukotskly, home of the Chukot or Chukchi aborigines, kinsmen of the Inupiaq and the Aleuts. Even in late June, the mountain tundra far below looks wintry, with hard, wind-worn snow in the ravines. Following old migration instincts, the Crane from the East will descend each spring to the great eastern peninsulas of Siberia, and some will wander west along the Arctic coast approximately fifteen hundred miles to the Yana River, where their breeding range meets that of the Siberian crane.

Off Asia's north Pacific coast, the airplane turns southward. In this clear weather, one can see most of Kamchatka, that vast and all but uninhabited land of volcanoes and great bears, blue lakes, mountain meadows, swift cold streams, and hard bright coast. Extending a thousand miles north and south, with scarcely a scar or a raw scrape or glint of man, it fairly resounds with emptiness and silence, like the pristine New World continent of great mountains and rivers that astounded the early voyagers along its north Pacific coast.

Off Kamchatka's tip, the Kurile Islands march south through the Pacific haze toward the Japanese archipelago, which continues in a southwest arc approximately as long as the Atlantic coast from Maine to Florida. Eventually the plane descends to refuel at Magadan, on the Siberian mainland, where even in late June, the barren Dzhugdzhur Mountains to the west are patched with snow. Beyond, the spruce tundra and boreal taiga, immense beyond reckoning, extend three thou- sand miles to the Ural Mountains and European Russia, in an all but unbroken forest composed of half the conifers and one third of the hardwoods left on earth.

From Magadan the plane heads out across the Sea of Okhotsk. The Siberian coastline reappears in the sprawling delta of the Amur River, shining in braids and floodplains that stretch away under the western sun to far smudges of upland and small mountains. The Amur drainage is the great river system of eastern Siberia and northern China, draining a watershed Of 716,200 square miles on its 2,700-mile journey from eastern Mongolia to the sea. With the Ussuri (in Chinese, Wusuli), which joins it from the south, the Amur serves as the north-eastern frontier between Russia and China, all the way from Inner Mongolia to great Lake Khanka -- or Xingkai Hu -- on China's border with Primorski Krai, Russia's maritime province on the Sea of Japan.