1. Ospreys have nested in Britain since the passing of the Ice Age. Gradually, with the growth of civilisation, the numbers of these large fish-eating birds dwindled. Their territories shrank with the spread of Man, until only the isolated mountainous regions of Scotland, in the far north of Britain, provided a safe refuge for the birds. By the end of the nineteenth century, even these high hills failed to offer sanctuary from poison, trap and gun, so that by the beginning of the First World War ospreys were extinct as breeding birds in Britain. They had flown far to the north, to the safer lands of Scandinavia.
2. Then, after an absence of almost half a century, migrant ospreys began to fly south from Scandinavia to reclaim their ancient territories in the Scottish highlands. By now the attitude of Man towards these birds had changed. Indeed, as news of the nesting birds spread, bird watchers grabbed their cameras and binoculars and flocked to the locality. Yet a new danger confronted the ospreys. Thieves tried to plunder their nests, for there were egg-collectors prepared to pay considerable sums of money to possess a batch of the rare osprey eggs, with their rich russet-red markings.
3. As a result, the Royal Society for the Protection of Birds mounted a constant guard over the nesting sites of the ospreys, and in particular over the first of them that had been discovered. Here the Society actively encouraged visitors and gave the nesting birds maximum publicity. Meanwhile, in remote valleys elsewhere in the Scottish highlands, other ospreys raised their young, the secret of their whereabouts closely guarded by the Society's wardens and by local residents.
4. On one such secret nest, close to a lake, crouched a large female osprey. Her eyes were half-closed, her head drooping as she shielded her two eggs beneath her chest. Meanwhile, from far away across the carpet of pine trees came a clear high-pitched whistle and seconds later her mate swept into view, his wings outstretched, a freshly caught trout gripped in one scaly claw. He circled the nest and came to rest on a nearby pine tree, one that was long dead, its white skeletal branches devoid of any bark. Once settled, he began to feed, leisurely tearing the flesh from the front half of the fish with his powerful hooked beak. He seemed oblivious of the female and her increasingly irritable call. At length, appearing to notice her for the first time, he picked up the remains of the trout in his claws and flew over to the nest. The female hissed a greeting, glaring at him with brilliant yellow eyes, and then, abandoning her eggs, she seized his offering and flew off to the dead pine tree to feed. Gingerly, the male took her place on the nest, easing himself down until the eggs settled comfortably against his flanks.
5. The female tore at the fish with her great hook of a beak. Having fed, she began to preen herself, running her feathers through her beak with meticulous care. Once her toilet was completed, the osprey launched herself from her perch, flew across to the nest and landed on the rim. The male needed no persuasion to leave the eggs. He soared into the sky to continue with his usual business of supporting and protecting his family. As he flew low over the trees, he thought he heard a rustling of leaves. Was it a buzzard? A bird of prey like that had to be driven off. He flew even lower to check. Nothing moved, and dismissing his fears he resumed his mission.
6. Unknown to him, a stranger had arrived on the scene. It was a young osprey, born two years previously on a nesting site some 15 kilometres away. On the bird's left leg was a ring, with a coded number and a name given to the osprey - Iasgair. It means fisherman. This osprey had successfully returned to his birth-place after his first flight south. He was discovering that there were more ospreys in the area, and as they colonised their own piece of territory it was becoming increasingly harder for young males like him to lay claim to a suitable habitat. So he flew from place to place, getting an intimate knowledge of his terrain and identifying those regions in which he was unwelcome.
7. Iasgair knew that a nest-site was jealously guarded by the parent ospreys and was best avoided. Yet, each time he located a nest, he felt drawn by some overwhelming compulsion to take a closer look, even though he knew from experience that his reception would be hostile. Today was no exception. He circled the area warily, his eye scanning the dark brooding female at the centre of the nest. Somewhere, he knew, there would be a watchful male perched on top of a tree, but the only tree that appeared suitable as a look-out post was deserted.
8. He dropped lower, until he could see the yellow eye of the hen bird cocked skywards, watching him as he made his descent. The hen sensed danger. Her mate was nowhere to be seen. In desperation she began to scream, the crest of feathers on her head raised in outrage. In spite of the impending peril, she did not move off her eggs. Iasgair glided over the nest, a mere metre above the sitting bird who hissed loudly in defiance. He was about to make another pass when the male bird came out of the sun.
9. Iasgair heard the thudding noise of the male bird's wings, and the whistle of air through the feathers. Before Iasgair could react, the male bird lashed out at him with its razor-sharp talons. Iasgair dived away just in time to avoid being decapitated. Nevertheless, he felt a violent blow on his rump and feathers exploded around him, almost blinding him. Iasgair was bewildered, and his inexperience in dealing with an older and more mature rival was evident.
10. While Iasgair was still confused, his attacker shot towards him again, but Iasgair did not linger to dispute the issue; he knew when he was beaten. He folded his wings, and, like an arrow falling, plunged towards the surface of the lake. Then, with his wings almost touching the water, he raced for the far shore. Honour now satisfied, the male bird followed at a discreet distance, and when he saw that the trespasser had no intention of returning, he broke off the pursuit, returning in triumph to the nest.