Last of the Curlews, page 2
When still a yard away, the male abruptly stopped. The whispering courtship twitter that had been coming from deep in his throat suddenly silenced, and a quick series of alarm notes came instead. The female′s behavior also suddenly changed. No longer meekly submissive, she was on her feet and stepping quickly away.
The male abandoned his courtship stance, lowered his head like a fighting cock and dashed at the female. She dodged sideways, and took wing. The male flew in pursuit, calling noisily and striking repeatedly at her retreating back.
The curlew′s mating passion had suddenly turned into an aggressive call to battle. The female was a trespasser on his territory, not a prospective mate, for at close range he had recognized the darker plumage and eccentric posture of a species other than his own. The other bird was a female of the closely related Hudsonian1 species, but the Eskimo curlew knew only, through the instinctive intuition set up by nature to prevent infertile matings between different species, that this bird was not the mate he awaited.
He chased her a quarter of a mile with a fury as passionate as his love had been a few seconds before. Then he returned to the territory and resumed the wait for the female of his own kind that must soon come.
Two curlew species, among the longest-legged and longest-billed in the big shorebird family of snipes, sandpipers, and plovers to which they belong, nest on the arctic tundra—the Eskimo curlew and the commoner and slightly larger Hudsonian. Though distinct species, they are almost indistinguishable in appearance.
The arctic day was long, and despite the tundra gales that whistled endlessly across the unobstructed land the day was hot and humid. The curlew alternately probed the mudflats for food and patrolled his territory, and all the time he watched the land′s flat horizons with eyes that never relaxed. Near midday a rough-legged hawk appeared far to the north, methodically circling back and forth across the river and diving earthward now and then on a lemming that incautiously showed itself among the reindeer moss. The curlew eyed the hawk apprehensively as the big hunter′s circling brought it slowly upriver toward the curlew′s territory. Finally the rough-leg crossed the territory boundary unmarked on the ground but sharply defined in the curlew′s brain. The curlew took off in rapid pursuit, his long wings stroking the air deeply and his larynx shrieking a sharp piping alarm as he closed in on the intruder with a body weight ten times his own. For a few seconds the hawk ignored the threatened attack, then turned back northward without an attempt at battle. It could have killed the curlew with one grasp of its talons, but it was a killer only when it needed food, and it gave ground willingly before a bird so maddened with the fire of the mating time.
The sun dipped low, barely passing from view, and the curlew′s first arctic night dropped like a grey mist around him. The tundra cooled quickly, and as it cooled the gale that had howled all day suddenly died. Dusk, but not darkness, followed.
The curlew was drawn by an instinctive urge he felt but didn′t understand to the dry ridge of cobblestone with the thick mat of reindeer moss at its base where the nest would be. In his fifth summer now, he had never seen a nest or even a female of his kind except the nest and mother he had briefly known in his own nestling stage, yet the know-how of courtship and nesting was there, unlearned, like a carry-over from another life he had lived. And he dozed now on one leg, bill tucked under the feathers of his back, beside the gravel bar which awaited the nest that the bird′s instinct said there had to be.
Tomorrow or the next day the female would come, for the brief annual cycle of life in the arctic left time for no delays.
The Gantlet
PHILOSOPHICAL TRANSACTIONS of THE ROYAL SOCIETY of LONDON giving some ACCOUNT of the present undertakings, studies and labours of the INGENIOUS in many considerable parts of the world. VOL. LXII for the year 1772.
Article xxix.
An account of the birds sent from Hudson’s Bay; with observations relative to their natural history; and Latin descriptions of some of the most uncommon. By Mr. J. Reinhold Forster, F.R.S.
From the factory at Hudson′s Bay, the Royal Society were favoured with a large collection of uncommon quadrupeds, birds, fishes, &c., together with some account of their names, place of abode, manner of life, uses, by Mr. Graham, a gentleman belonging to the settlement on Severn River; and the governors of the Hudson′s Bay Company have most obligingly sent orders, that these communications should be from time to time continued.
(The birds described by Mr. Forster being all introduced into Mr. Latham′s ornithological volumes, under the same titles, it becomes unnecessary to give the Latin descriptions, which are therefore omitted from these transactions.)
1. Falco Columbarius. Pigeon hawk. It is migratory. 2. . . . 3. . . . 4. . . .
18. New species. Scolopax Borealis. Eskimaux curlew. This species of curlew, is not yet known to the ornithologists; the first mention made of it is in the Faunula Americae Septentrionalis, or Catalogue of North American Animals. It is called Wee-kee-me-nase-su, by the natives; feeds on swamps, worms, grubs, &c. Visits Albany Fort in April or beginning of May; breeds to the northward, returns in August, and goes away southward again the latter end of September in enormous flocks.
Chapter Two
The hot days and chilling nights raced by, the snowdrifts disappeared even from the shaded hollows, the austere browns and greys of the tundra became a flaming carpet of pink and yellow blooms, and the female curlew never came. Other shorebirds came in their hundreds, fought for their territories, mated, nested and prepared to bring forth the new cycle of life they had flown six or eight thousand miles to create. The male curlew fought insanely with every plover and sandpiper that crossed his territory boundary until the outer perimeters were flecked with the brown feathers of trespassers that had retreated too slowly before the curlew′s onslaughts. The mating hormones poured out by his glands could only dam up within him like an explosive charge.
Instinctively the curlew fought every other shorebird that ventured near, yet in his instinctive behavior pattern there was no enmity for the buntings, longspurs and ptarmigans that also occupied the tundra—birds not biologically related and not competitors for the same insect food he would need for his own nestlings when the female came. When a female willow ptarmigan built her nest and laid her twelve buff eggs less than fifteen feet from the moss hummock where the curlew′s nest would be, the curlew ignored her and in a few days forgot she was there.
The nights grew darker and longer. The tiny, brilliant flowers of the tundra dried into wisps of silk-plumed seed. Close by, a pair of golden plover, their black bellies and breasts glistening in the low rays of a morning sun, began calling excitedly and flying in rapid circles. The curlew knew their young had come, and like the young of all shorebirds, already well developed at birth, they had left the nest and were running about before the shells of the eggs that had held them were dry. The arctic summer was waning.
Several of the plovers′ down-covered young scampered into the curlew′s territory and the mother followed them with food. The curlew whistled a warning and flew toward her. But the call of her young was stronger than the fear of another much larger bird, and the plover stood her ground, her wings spread protectively before the tiny, peeping balls of yellow fluff that squirmed downward into the mat of reindeer moss. The curlew swerved upward without striking her. And he didn′t attack again. Instead he circled to a rocky hummock a hundred feet away, alighted, watched the plover feeding her young for a moment or two, and then forgot her.
Within the curlew the annual rhythm of glandular activity had passed its peak and begun to ebb, and its product, the belligerent drive of the mating time, was dying. A new urge was replacing it. Where before, defense of the territory was an overriding demand that took priority over even the search for food, the curlew was now feeling the first stirrings of a restless call to move. No female had come. The territory was losing its meaning.
Periodically the curlew flew back at the golden plover, but when the plover refused to fly the curlew would lose interest and forget her again. This went on for most of a day, the curlew suddenly remembering that there were intruders on his territory, then just as suddenly forgetting them. The next day other shorebirds moved in and out of the territory. Now the curlew ignored them. Once he flew far down river and was gone a couple of hours, the first time he had left the territory since arriving almost two months before.
Around him the young shorebirds of the year were maturing rapidly and their parents were abandoning them to fend for themselves. The disassociation between parents and young was abrupt and complete, the parents forming their own flocks, the young birds theirs.
It was late July. The tundra potholes and their muddy edges were teeming with the water insects and crustaceans on which the shorebirds fed. Food was at its peak of abundance and winter was still a couple of months away, but the arctic had served its purpose and now the distant southland was calling the shorebird flocks, many weeks before there was any real need for them to leave. The curlew who had fought savagely all summer to be alone, now felt a pressing desire for companionship.
There was no reasoning or intelligence involved. The curlew was merely responding in the ages-old pattern of his race to the changing cycle of physiological controls within him. As days shortened the decreasing sunlight reduced the activity of the bird′s pituitary gland. The pituitary secretion was the trigger that kept the reproductive glands pouring sex hormones into the bloodstream, and as the production of sex hormones decreased, the bird′s aggressive mating urge disappeared and the migratory urge replaced it. It was entirely a physiological process. The curlew didn′t know that winter was coming again to the arctic and that insect eaters must starve if they remained. He knew only that once again an irresistible inner force was pressing him to move.
But somewhere in his tiny, rudimentary brain the simple beginnings of a reasoning process were starting. Why was he always alone? When the rabid fire of the mating time burned fiercely in every cell, where were the females of his species that the curlew′s instinct promised springtime after springtime? And now with the time for the flocking come, why in the myriads of shorebirds and other curlews were there none of the smaller and lighter-brown curlews he could recognize as his own kind?
A few days later the lure of the territory disappeared entirely and the curlew rose high and flew southward for a couple of hours without alighting. He came down finally to feed on a small mudflat where a river emptied into a large lake. The tundra was now disgorging its summer population of shore-birds and flock after flock of southward moving sandpipers passed by. One flock of long-legged shorebirds, flying in a wavering V, swept low along the lakeshore. The curlew stopped his feeding and called excitedly, for the flight pattern and flock formation could only be curlew. The flock wheeled without breaking formation, moving with the precision and instantaneous timing of a single organism, as though one nerve centre controlled the movements of every bird. On stiffened, downcurved wings they glided in to the mudflat. The Eskimo curlew ran toward them, then stopped abruptly after a few strides and nonchalantly resumed his feeding. They were Hudsonian curlews with the shorter bills and buffy underparts that marked them as birds of this nesting.
The curlew didn′t know that this other species, almost identical outwardly, was a slower flying bird unsuited as a migration companion. He didn′t know that young shorebirds of the year develop their full wing strength late and are left behind by the adults to follow by instinct the perilous eight-thousand-mile southward route they have never seen before. His instinctive behavior code, planted deep in his brain by the genes of countless generations, told him only what do, without telling him why. His behavior was controlled not by mental decisions but by instinctive responses to the stimuli around him. He desired the association of a flock, but the Hudsonians had failed to release the flocking response in his inner brain and now he ignored them in his feeding. When they flew again a short time later, the Eskimo curlew hardly noted their departure. In a land pulsing with the wingbeats of migrating shorebirds, the curlew was alone again.
By afternoon the mudflat was dotted with the darting forms of shorebirds that had stopped to feed. Most of them kept together in flocks of their own species. At dusk the flocks ceased feeding and took off, one by one, until only the curlew remained, the birds of each flock whistling sibilantly to each other to retain formation in the falling darkness.
They circled high until a half mile or so above the tundra, then leveled off and headed southward. It was usual for the shorebirds to migrate principally at night, for their digestion and energy consumption were rapid and the daylight was required for feeding. The high level of energy that migration demanded could be maintained only by timing the flights so that they ended with the dawn when feeding could be at once resumed.
Far above him, the curlew could hear the faint, lisping notes of the arctic migrants pouring south to a warmer land. Needles of ice began forming at the shallow edges of the mudflat puddles. The bird′s instinct rebelled at the idea of flying alone, yet when he called shrilly into the cold night there was no answer, and the time had come when he had to move.
He turned into the breeze, held his wings extended outward and adjusted the angle—leading edge up and trailing edge down—until he could feel the lifting pressure of the wind beneath them. Of all the shorebirds′ wings, the Eskimo curlew′s—long, narrow and gracefully pointed—were best adapted for easy, high-speed flight. Even standing motionless with wings extended in the faint, night breeze, the bird was weightless and almost airborne. He pushed off gently with his legs, took a few rapid wingbeats with the flight feathers twisted so that they bit solidly into the air, and rose effortlessly. He climbed sharply for more than a minute until the tundra almost vanished in the grey dark below, then he leveled off and picked up speed with a slower, easier wing-beat. The air rushed past him, pressing his body feathers tightly against the skin. The migration had begun. Even the curlew′s simple brain sensed vaguely that the unmarked fly-way ahead reaching down the length of two continents was a long, grim gantlet of storm, foe and death.
Yet even now, before the austere flatlands of the arctic had totally disappeared in the horizon mists behind him, the curlew was feeling the first faint stirrings of another year′s mating call that would drive him back to await the female when springtime greened the arctic lichens again.
The Gantlet
. . . Being the hitherto unpublished notes of Lucien McShan Turner on the birds of Ungava. . . . I saw no Esquimaux curlew until the morning of the 4th of September, 1884, as we were passing out from the mouth of the Koksoak River. Here an immense flock of several hundred individuals were making their way to the south. . . .
Chapter Three
The curlew′s wings beat with a strong, rapid, unchanging rhythm hour after hour. The strokes were deep, smooth and effortless, the wings sweeping low beneath his belly at every downstroke and lifting high over the back with each return. Each stroke was an intricate series of gracefully coordinated actions merged with split-second precision into a single, smooth movement, for the curlew′s wing was a wing and propeller combined. Each portion of the wing had a different flight role to play.
The sturdy inner half next to the body deflected the air-stream as an aircraft wing does, so that pressure developed against the undersurface and suction above—the lift that produces flight. It accomplished this with its aerodynamic shape alone. The flapping of the wings provided forward drive, but was not directly responsible for keeping the bird airborne.
The outer half of the curlew′s wing, composed of the ten stiff flight feathers overlapping like a Venetian blind, was the propeller that drove the bird forward, producing the airflow that gave lift to the inner wing. The wing bones were along the leading edge of the wing, and most of the wing behind them consisted of flexible feathers. Hence on the downstroke the pressure of air twisted the wing, bony front edge down and trailing feather edge up, which turned it into a propeller blade pushing air backward and driving the bird ahead. The wingtip flight feathers were additional small propellers, for each central quill was also nearer the front than the rear, so that air pressure twisted each one individually, the same way the whole wing twisted, pushing air backward and adding forward drive. With the upstroke, the air pressure bent the wing and feathers the opposite way, now front edges up and rear edges down, so that the push of feathers against the air still produced a forward propulsion, and the lift force of the inner wing remained uninterrupted with no loss of altitude on the upstroke.
It was all reflexive, automatic, too rapid for conscious control. The curlew completed three or four wingbeats a second to give him a flight speed of fifty miles an hour.
Occasionally one of the curlew′s wings would bite into the harder, spiraling air of a vortex left by the wingtips of a migrating shorebird ahead of him, for even the passage of another bird left a trail in the air that the curlew′s delicately sensitized wings could detect. Usually this alteration in the air pattern was the curlew′s first warning that he was overtaking a flock of birds ahead. When he found one of these vortexes, the curlew took advantage of it and followed it in with one wing riding the updraft edge of the horizontal column of spiraling air. In this way he found a degree of lift ready-made for him and his own wings could work a little easier.
But no other shorebird except the golden plover flew as fast as the curlew did, and each time he slowly overtook the bird producing the vortex ahead. First he would hear the faint twitter of a flock′s flight notes, the vortex would grow stronger, then the birds would appear as blurred figures against the grey sky in front. The curlew would fly with them for a time, but his greater speed would gradually drive him ahead. Then once more he would be flying alone.
