Now it was corn-planting time on the Nebraska and Dakota prairies and great steel monsters that roared like the ocean surf were crossing and recrossing the stubble fields leaving black furrows of fresh-turned soil in orderly ranks behind them. Most of the shorebirds shunned the growling machines and the men who were always riding them. Yellowlegs and sandpipers would stop their feeding and watch warily when the plowman was still hundreds of yards off, then if the great machine came closer they would take wing, whistling shrilly, and not alight again until they were a mile away. But the Eskimo curlews had little fear. Far back in the species′ evolutionary history they had learned that, for them, a highly developed fear was unnecessary. Their wings were strong and their flight so rapid that they could ignore danger until the last moment, escaping fox or hawk easily in a last-second flight. So their fear sense had disappeared, as all unused faculties must, and while other shore-birds relied on wariness and timidity for survival, the Eskimo curlew relied entirely on its strength of wing.
The curlews followed the roaring machines closely, for the white grubs and cutworms that the plows turned up were a rich and abundant food.
All the time their reproductive glands had been swelling in the annual springtime rhythm of development, the development keeping pace with the northward march of spring, so that their bodies and the tundra would become ready simultaneously for the nesting and egg laying. As the physical development came close to the zenith of its cycle, there was an intensification of emotional development too. With high body temperatures and rapid metabolism, every process of living is faster and more intense in birds than any other creature. When the breeding time approaches they court and love with a fervor and passion that matches the intensity of all their other life processes.
Now many times a day the male curlew′s mounting emotion boiled over into a frantic display of love. It had become a much more violent display than the earlier acts of courtship. First the male would spring suddenly into the air and hover on quivering wings while he sang the clear, rolling, mating song—a song much more liquid and mellow now than at any other time of year. After a few seconds his wings would beat violently and he would rise almost straight upward, his long legs trailing behind, until he was a couple of hundred feet above the prairie. There he would hover again, singing louder so that bursts of the song would reach the female, bobbing and whistling excitedly far below. Then he would close his wings and dive straight toward her, swerving upward again in the last few feet above her head and landing several yards away.
Panting with emotion, singing in loud bursts, his throat and breast inflated with air and the feathers thrust outward, he would hold his wings extended gracefully over his back until the female invited the climactic approach. She would bob quickly with quivering wings and call with the harsh, food-begging notes of a fledgling bird. Then he would dash toward her, his wings beating vigorously again so that he was almost walking on air. Their swollen breasts would touch. The male′s neck would reach past her own and he would tenderly preen her brown wing feathers with his long bill.
It would last only a few seconds, and the male would dash away again. He would pick up the largest grub he could find and return quickly to the female. Then he would place it gently into her bill. She would swallow it, her throat feathers would suddenly flatten, her wings stop quivering, and the lovemaking abruptly end. For as yet the courtship feeding was the love climax; their bodies were not yet ready for the final act of the mating.
For a couple of hours after each courtship demonstration the passion and tenseness of the approaching mating time would relax, for the love display was a stopgap that satisfied them emotionally while they awaited the time for the physical consummation.
They moved north steadily, a couple of hundred miles each night. The male′s sexual development matured first and he was ready for the finalizing of the mating. His passion became a fierce, unconstrainable frenzy and he spent most of each day in violent display before the female. But with each courtship feeding her tenseness suddenly relaxed and the display would end.
It was mid-May and the newly plowed sections of rolling, Canadian prairie steamed in the warming sun. They followed closely behind the big machine with the roar like an ocean surf. The grubs were fat and they twisted convulsively in the few seconds that the sun hit them before the curlews snapped them up. Now the snows of the tundra would be melting. In the ovaries of the female the first of her four developing eggs was ready for the life-giving fertilization.
The male flung himself into the air, his love song wild and vibrant. He hovered high above the black soil of the prairie with its fresh striated pattern of furrows. The roar of the big machine stopped and the curlew hardly noted the change, for his senses were focused on the female quivering excitedly against the dark earth far below. The man on the tractor sat stiffly, his head thrown back, staring upward, his eyes shaded against the sun with one hand. The curlew dove earthward and the female called him stridently. He plucked a grub from the ground and dashed at her, his neck outstretched, wings fluttering vigorously. He saw the man leap down from the tractor seat and run toward a fence where his jacket hung. Normally, at this, even the curlews would have taken wing in alarm, but now the female accepted the courtship feeding and her wings still quivered in a paroxysm of mating passion. She crouched submissively for the copulation and in the ecstasy of the mating they were blind to everything around them.
The thunder burst upon them out of a clear and vivid sky. The roar of it seemed to come from all directions at once. The soil around them was tossed upward in a score of tiny black splashes like water being pelted with hail.
The male flung himself into the air. He flew swiftly, clinging close to the ground so that no speed was lost in climbing for height. Then he saw the female wasn′t with him. He circled back, keering out to her in alarm. Her brown body still crouched on the field where they had been. The male flew down and hovered a few feet above her, calling wildly.
Then the thunder burst a second time and a violent but invisible blow blasted two of the biggest feathers from one of his extended wings. The impact twisted him completely over in midair and he thudded into the earth at the female′s side. Terrified and bewildered at a foe that could strike without visible form, he took wing again. Then the bewilderment overcame his terror and he circled back to his mate a second time. Now she was standing, keering also in wild panic. Her wings beat futilely several times before she could raise herself slowly into the air. She gained height and flight speed laboriously and the male moved in until he was close beside her.
He continued to call clamorously as he flew, but the female became silent. They flew several minutes and the field with the terrifying sunlight thunder was left far behind. But the female flew slowly. She kept dropping behind and the male would circle back and urge her on with frantic pleas, then he would outdistance her again.
Her flight became slower and clumsy. One wing was beating awkwardly and it kept throwing her off balance. The soft buffy feathers of the breast under the wing were turning black and wet. She started calling to him again, not the loud calls of alarm but the soft, throaty quirking of the love display.
Then she dropped suddenly. Her wings kept fluttering weakly, it was similar to the excited quivering of the mating moment, and her body twisted over and over until it embedded itself in the damp earth below.
The male called wildly for her to follow. The terror of the ground had not yet left him. But the female didn′t move. He circled and recircled above and his plaintive cries must have reached her, but she didn′t call back.
A long time later he overcame the fear and landed on the ground close to her. He preened her wing feathers softly with his bill. When the night came the lure of the tundra became a stubborn, compelling call, for the time of the nesting was almost upon them. He flew repeatedly, whistling back to her, then returning, but the female wouldn′t fly with him. Finally he slept close beside her.
At dawn he hovered high in the grey sky, his lungs swelling with the cadence of his mating song. Now she didn′t respond to the offer of courtship feeding. The tundra call was irresistible. He flew again and called once more. Then he leveled off, the rising sun glinted pinkly on his feathers, and he headed north in silence, alone.
The snow-water ponds and the cobblestone bar and the dwarfed willows that stood beside the S twist of the tundra river were unchanged. The curlew was tired from the long flight. But when a golden plover flew close to the territory′s boundary he darted madly to the attack. The arctic summer would be short. The territory must be held in readiness for the female his instinct told him soon would come.