SWIFTS, SWALLOWS AND MARTINS
WHEN the trout-fisherman sees the first martins and swallows dipping over the sward of the water-meadows and skimming the surface of the stream in hot pursuit of such harried water-insects as have escaped the jaws of greedy fish, he knows that summer is coming in. The signs of spring have been evident in the budding hedgerows for some weeks. The rooks are cawing in the elms, the cuckoo's note has been heard in the spinney for some time before these little visitors pass in jerky flight up and down the valley. Then, a little later, come the swifts—the black and screaming swifts—which, though learned folk may be right in sundering them utterly from their smaller travelling companions from the sunny south, will always in the popular fancy be associated with the rest. Colonies of swifts, swallows, and martins are a dominant feature of English village life during the warm months; and though there are fastidious folk who take not wholly culpable exception to their little visitors on the score of cleanliness, most of us welcome them back each year, if only for the sake of the glad season of their stay. If, moreover, it is a question of choice between these untiring travellers resting in our eaves and the stay-at-home starling or sparrow, the choice will surely fall on the first every time.
The swift is the largest and most rapid in its flight, and its voice has a penetrating quality lacking in the notes of the rest. Swifts screaming in headlong flight about a belfry or up and down a country lane are the embodiment of that sheer joy of life which, in some cases with slender reason, we associate peculiarly with the bird-world. Probably, however, these summer migrants are as happy as most of their class. On the wing they can have few natural enemies, though one may now and again be struck down by a hawk; and they alight on the ground so rarely as to run little risk from cats or weasels, while the structure and position of their nests alike afford effectual protection for the eggs and young. Compared with that of the majority of small birds, therefore, their existence should be singularly happy and free from care; and though that of the swift can scarcely, perhaps, when we remember its shrill voice, be described as one grand sweet song, it should not be chequered by many troubles. The greatest risk is no doubt that of being snapped up by some watchful pike if the bird skims too close to the surface of either still or running water, and I have even heard of their being seized in this way by hungry mahseer, those great barbel which gladden the heart of exiled anglers whose lot is cast on the banks of Himalayan rivers.
It is, however, the sparrows and starlings, rivals for the nesting sites, who show themselves the irreconcilable enemies of the returned prodigals. Terrific battles are continually enacted between them with varying fortunes, and the anecdotes of these frays would fill a volume. Jesse tells of a feud at Hampton Court, in the course of which the swallows, having only then completed their nest, were evicted by sparrows, who forthwith took possession and hatched out their eggs. Then came Nemesis, for the sparrows were compelled to go foraging for food with which to fill the greedy beaks, and during their enforced absence the swallows returned in force, threw the nestlings out, and demolished the home. The sparrows sought other quarters, and the swallows triumphantly built a new nest on the ruins of the old. A German writer relates a case of revolting reprisal on the part of some swallows against a sparrow that appropriated their nest and refused to quit. After repeated failure to evict the intruder, the swallows, helped by other members of the colony, calmly plastered up the front door so effectually that the unfortunate sparrow was walled up alive and died of hunger. This refined mode of torture is not unknown in the history of mankind, but seems singularly unsuited to creatures so fragile.
The nests of these birds show, as a rule, little departure from the conventional plan, but they do adapt their architecture to circumstances, and I remember being much struck on one occasion by the absence of any dome or roof. It was in Asia Minor, on the seashore, that I came upon a cottage long deserted, its door hanging by one hinge, and all the glass gone from the windows. In the empty rooms numerous swallows were rearing twittering broods in roofless nests. No doubt the birds realised that they had nothing to fear from rain, and were reluctant to waste time and labour in covering their homes with unnecessary roofs.
Most birds are careful in the education of their young, and indeed thorough training at an early stage must be essential in the case of creatures that are left to protect themselves and to find their own food when only a few weeks old. Fortunately they develop with a rapidity that puts man and other mammals to shame, and the helpless bald little swift lying agape in the nest will in another fortnight be able to fly across Europe. One of the most favoured observers of the early teaching given by the mother-swallow to her brood was an angler who told me how, one evening when he was fishing in some ponds at no great distance from London, a number of baby swallows alighted on his rod. He kept as still as possible, fearful of alarming his interesting visitors, but he must at last have moved, for, with one accord, they all fell off his rod together, skimmed over the surface of the water and disappeared in the direction from which they had come a few moments earlier.
Swifts fly to an immense height these July evenings, mounting to such an altitude as eventually to disappear out of sight altogether. This curious habit, which is but imperfectly understood, has led to the belief that, instead of roosting in the nest or among the reeds like the swallows, the males, at any rate, spend the night flying about under the stars. This fantastic notion is not, however, likely to commend itself to those who pause to reflect on the incessant activity displayed by these birds the livelong day. So rarely indeed do they alight that country folk gravely deny them the possession of feet, and it is in the last degree improbable that a bird of such feverish alertness could dispense with its night's rest. No one who has watched swifts, swallows and martins on the wing can fail to be struck by the extraordinary judgment with which these untiring birds seem to shave the arches of bridges, gateposts, and other obstacles in the way of their flight by so narrow a margin as continually to give the impression of catastrophe imminent and inevitable. Their escapes from collision are marvellous; but the birds are not infallible, as is shown by the untoward fate of a swallow in Sussex. In an old garden in that county there had for many years been an open doorway with no door, and through the open space the swallows had been wont, year after year, to fly to and fro on their hunting trips. Then came a fateful winter during which a new owner took it into his head to put up a fresh gate and to keep it locked, and, as ill luck would have it, he painted it blue, which, in the season of fine weather, probably heightened the illusion. Back came the happy swallows to their old playground, and one of the pioneers flew headlong at the closed gate and fell stunned and dying on the ground, a minor tragedy that may possibly come as a surprise to those who regard the instincts of wild birds as unerring.
That the young swallows leave our shores before their elders—late in August or early in September—is an established fact, and the instinct which guides them aright over land and sea, without assistance from those more experienced, is nothing short of amazing. The swifts, last to come, are also first to go, spending less time in the land of their birth than either swallows or martins. The fact that an occasional swallow has been seen in this country during the winter months finds expression in the adage that "one swallow does not make a summer," and it was no doubt this occasional apparition that in a less enlightened age seemed to warrant the extraordinary belief, which still ekes out a precarious existence in misinformed circles, that these birds, instead of wintering abroad, retire in a torpid condition to the bottom of lakes and ponds. It cannot be denied that these waters have occasionally, when dredged or drained, yielded a stray skeleton of a swallow, but it should be evident to the most homely intelligence that such débris merely indicates careless individuals that, in passing over the water, got their plumage waterlogged and were then drowned. It seems strange that Gilbert White, so accurate an observer of birds, should actually have toyed with this curious belief, though he leant rather to the more reasonable version of occasional hybernation in caves or other sheltered hiding-places. The rustic mind, however, preferred, and in some unsophisticated districts still prefers, the ancient belief in diving swallows, and no weight of evidence, however carefully presented, would shake it in its creed. Fortunately this eccentric view of the swallow's habits brings no harm to the bird itself, and may thus be tolerated as an innocuous indulgence on the part of those who prefer this fiction to the even stranger truth.
ไม่มีความคิดเห็น:
แสดงความคิดเห็น