The curlew knew that they had to continue flying eastward to keep the storm from overtaking them again, but it was a simple, uncolored, matter-of-fact knowledge. There was no lingering emotional reaction, no fear. The terrors of the snow-filled sky, the plovers forced into the sea, were forgotten almost immediately. Only the fact of the storm itself was remembered, and it was remembered not in panic or fright, but merely as a natural foe that was there and had to be avoided.
But their course eventually had to be southward, not eastward. To the east for four thousand miles there was only empty sea. After half an hour the curlew turned the flock southward, and they flew south unhindered for almost another half hour before the eastward-moving storm front enveloped them again. At the first big drops of rain, the curlew veered sharply to the east once more and in a few minutes the flock reentered clear air.
In the three hours that remained before dawn, they repeated this many times, flying south until the rain overtook them, then veering eastward to get ahead of it again. They were on a southerly course when the yellowing dawn pierced a murky eastern sky. Daylight came swiftly, changing the black of the sea to a cold green, but there was no sun. They flew southward for an hour, then two hours, and the cloud cover grew thinner and the day brightened and this time the storm didn′t reappear. Even the grey, bumpy clouds of the western sky vanished and in the east the sun cut like a torch through the dissolving mists. The air remained cold, but in a short time the sun stood alone in a blue and otherwise empty sky.
The birds had worked southward around the storm. The snow clouds of the night, what would be left of them, would be breaking up now far to the north over the codfish shoals of Newfoundland′s Grand Banks.
In midmorning the air warmed and eddying wisps of fog began rising off the sea. The sky above remained blue and clear, but at times the sea below was completely hidden by layers of mist. They were approaching the spot where the icy Labrador current flowing southward out of the arctic met the tepid northward-flowing tropic waters of the Gulf Stream. Here the Gulf Stream is deflected eastward past Newfoundland into mid-Atlantic. After an hour of intermittent fog the sea lay bare again. Then its pale green arctic waters changed abruptly to a deep indigo blue with a line of demarcation as sharp as a line between water and shore. They were over the Gulf Stream, a product of the tropics. The green of the Labrador current, last feature of the arctic, faded behind them.
Their wings beat mechanically, without change of pace or fatigue. The air warmed constantly, for each hour put them fifty miles southward. The only change in the drowsy monotony of flight came when, at intervals, they let themselves drop low to skim the wavetops for perhaps an hour before climbing again.
At low altitude the sea, like the arctic tundra, revealed that its surface mask of lifeless barrenness was illusion. Life was there, abundantly, when the birds came low enough to see it. At times shimmering discs of jellyfish dotted the sea for miles; the sun glinted metallically off a thousand silver flanks as schools of small fish darted upward into the surface layers; and sometimes there were clouds of minute one-celled plankton creatures, each one a microscopic grain of orange pigment by itself, but in their billions they colored miles of sea a vivid red.
Down close to the water, there were other birds too, birds that spent most of their lives skimming the open vistas of sea, touching land only when the irresistible urge of the nesting time drove them ashore. Wilson′s petrels fluttered mothlike and dodged erratically between wave crests, their white rumps flashing like tiny breakers as they fed incessantly on the sea′s crustacea and plankton. Phalaropes that had nested on the arctic tundra with their shorebird kin had returned now to the sea, which would lure them until another nesting time came. Occasionally a bigger shearwater soared past on black, motionless wings that skilfully utilized the updrafts created atop each wave crest by the upward deflection of surface wind. But these were true birds of the sea. The sea gave them food, and when their wings tired the sea also gave them rest, for they swam as skilfully as they flew.
The curlew and plovers could only keep flying, waiving food and rest until the landfall came.
By evening they had crossed the eastward-flowing arm of the Gulf Stream and were over the immense two-million-square-mile eddy of the mid-Atlantic where no currents came to stir the brackish water and where the rubbery fronds of sargassum weed collected in the great floating islands of the Sargasso, weirdest of all seas. They had flown almost twenty-four hours, yet there was no fatigue in the pulsing muscles of their breasts.
Vast meadows of brown floating algae passed beneath. At intervals when the birds came low, they would see flying fish with great winglike pectoral fins extended, skimming over the soggy knots of seaweed. There were crabs, shrimps and sea snails clinging to the seaweed stems. In other years this first dusk had put the curlew within sight of Bermuda′s flat-topped Sear′s Hill, but the night′s storm had driven them far to the eastward, and now the sun set in an empty sea. When darkness came, the sea flamed with the cold white light of millions of phosphorescent creatures.
The curlew led the flock upward and throughout the night they flew steadily at a height of a half mile or so, the birds calling intermittently to each other. When the curlew was leading the flock his senses had to be kept sharply tuned to the vagaries of wind and the cosmic impulses that his brain interpreted into a sense of direction. When he dropped back for rest, he could fly in a half-sleep, his wings beating automatically, his eyes half shut, following subconsciously the trailing air vortex of the bird ahead of him.
That night the North Star and the familiar constellations of the arctic sky dropped almost to the northern horizon. New star groups rose to the south. And shortly before dawn the wind freshened, a warm, firm wind that blew with monotonous constancy out of the northeast. They had entered the region of the trade winds. It was a quartering tail wind that gave them almost another ten miles an hour of speed.
Day, when it came, was hot despite the wind. Occasionally the grey-blue form of a shark glided close to the sea′s surface. This was the rim of the tropics, and the sea turned bluer, and condensation of the hot rising air gave the sky a lumpy patchwork of white cumulus clouds. The cloud shadows dappled the blue water with constantly changing patterns of grey. Occasionally there were thicker knobs of cloud that hung motionless on the western horizon, the island signposts of the sea, for every island had its cap of cloud that was visible far beyond the island′s own horizons. These were the Lesser Antilles of the outer Caribbean. And far beyond the rim of the sea, ahead, another twelve hours of flying away, were the jungles and mountains of South America.
Now their breasts and wing tendons were tiring from the thirty-six hours of flying behind them. Flight was no longer the effortless subconscious reflex it had been. It had become a function that had to be willed, only conscious concentration on the task kept their flagging wings working. Two nights and a day without food had slowed their body processes. Now they had to pant rapidly in the hot tropic air, their bills slightly agape, to capture the oxygen supply their lungs demanded. Three of the plovers, one-year-olds making the long ocean flight for the first time, dropped slowly behind and the curlew at the point of the flock slowed to a flight speed that the weaker birds could maintain.
The curlew knew that where the thick clouds dotted the western horizon there were islands only an hour or two′s flight away. But he possessed an instinctive knowledge, developed through millennia of his species′ evolution, that there was not enough food on small tropical islands to feed the numbers of shorebirds making this ocean flight, and hence he held instinctively to the original course. And he knew that long before the South American coast could be reached a third night would be upon them. Then the landfall would come in darkness and if the night were cloudy and black there could be no landing even then until the dawn light revealed the outlines of Venezuela′s mangrove swamps and river sandbars.
The day passed with interminable slowness, the sun sank finally into the Caribbean and the night dropped quickly without twilight. Then the overcast moved in to shut out moon and stars, and rain began falling, for they were reaching the tropics at the height of the rain season. But it was a light, fine rain that cooled the air and made breathing easier. And it was a signal that the coast was approaching.
For another two hours they flew through rain. The curlew could see nothing, but he knew immediately when they left the sea and were flying over land. First the rumble of surf came up through the darkness, then the air became turbulent with the thermal updrafts lifting off the warmer land.
They could do nothing but fly on for hours longer. And now, with the knowledge that land lay below, the continuance of flight became the harshest ordeal of all. Every wing-beat was a torturing battle with lethargy and fatigue. And much of the energy used was now wasted, for their flight feathers were frayed and ragged, no longer capable of the sharp, propelling bite of feather against air, which had made flights so easy and effortless when they left Labrador.
The curlew knew that once they had crossed the coastal strip with its beaches and river estuaries, there was nothing beyond for a hundred and fifty miles but the dense tangle of mangrove swamp where a landing was as impossible as on the open sea. Now, even if the night cleared, they would have to push on regardless until the flat, grassy llanos of the Venezuelan interior spread out below them. Despite the growing heaviness of their wings, the curlew led them upward to clear the coastal mountains he knew were ahead. The climb was a torturing anguish. They leveled off, but it brought no respite to the burning pangs of fatigue that throbbed in every fiber of their small bodies.
The night remained black. At last the dawn came, not yellow or red, but in a somber pall of greyness. The land below was a drowned and sodden land of mud, water and swollen rivers, like the springtime tundra of the arctic. The broad treeless valley of the great Orinoco spread in every direction as far as the grey pall would let them see. The rain still fell.
They had flown without rest or food for almost sixty hours. From a land of snow and the northern lights, they had come nonstop to a land that was steaming with the rank growth of the tropics. Below them were hundreds of miles of mudflats and grassy prairie that teemed with the abundance of aquatic insect food that only the months of tropical rain could produce.
With the first misty light of the dawn, the curlew arched his stiffened wings and plunged downward in an almost vertical dive. He had spanned the length of a continent since his wings had last been still. The plovers followed. The flock touched down.
But not a bird rested, for feeding had to come first. Their stomachs had been empty fifty-five hours and they had flown close to three thousand miles on the fuel stored in Labrador as body fat. When the flight began, their breasts had been round and swollen. Now they were gaunt, constricted, the breastbones protruding in sharp ridges through the feathers. In less than three days each bird had lost more than a third of its body weight—two ounces for the plovers, four or five for the curlew.
They fed rapidly until midmorning, and only then did they rest. On the broad savannahs abutting the Orinoco, food was abundant. They fed again for several hours before the first tropic night brought darkness.