HERRING FISHING. 423 themselves after spawning in those unfathomed depths, that swarm with insects upon which they feed. This innumerable army begins to put itself in motion in the spring, in order to deposit its spawn in the warmer latitudes: its forerunners appear off the Shetland islands in April and May, but the grand shoal does not appear till June; it is attended by gannets, and other sea birds, in prodigious multitudes, and vast numbers of dog-fish and porpoises, all of which are supported without sensibly diminishing a host, in which millions more or less are of no account. The breath and depth of the main body is such as to alter the appearance of the very ocean; it is divided into distinct columns of five or six miles in length, and three or four in breadth, driving the water before them with a very perceptible rippling; sometimes they sink for the space of ten or fifteen minutes, then rise again to the surface, and in bright weather exhibit a resplendency of colours like a field of gems. The first check that this army experiences in its march southwards is from the Shetland Isles, which divide it into two parts; the eastern wing passes on to Yarmouth, the great and ancient mart for herrings, filling every bay and creek with its numbers; it then advances through the British channel, and disappears. The western wing, after offering itself to the great fishing stations in the Hebrides, proceeds towards the north of Ireland, where it is obliged to make a second division; the one takes to the western side, and is scarcely perceived, being soon lost in the immensity of the Atlantic; but the other, passing into the Irish sea, feeds and rejoices the inhabitants of most of the coasts that border on it. Towards the end of the month, the common swallow disappears. There have been various conjectures concerning the manner in which these birds, and some of their kindred species, dispose of themselves during the winter. The swift is the only one of this genus, about which there appears to be little or no controversy, its early retreat and strength of wing rendering its migration almost certain; but with regard to the rest, namely, the swallow, the martin, the sand martin, there are three current opinions, each of which deserves consideration. The first, which is principally adopted by the Swedish and other northern naturalists, is, that these birds pass the cold months in a torpid state under water. This apparently improbable supposition is supported by the following arguments: the places in which the species in question are seen, the latest and earliest in the year, are the banks of large deep ponds and rivers. About the time of their disappearing, they are observed to roost in vast numbers on branches of trees that overhang the water, which by their weight are observed to be bent, so as nearly to touch the surface. Some obscure reports of swallows having been dragged up in a torpid state from the bottom of lakes, have been eagerly embraced by the favourers of this hypothesis, and the proof is thus supposed to be complete. Against this opinion there are the following obvious arguments: the swallow tribe live wholly on insect-food, and it is in the neighbourhood of waters that gnats and various other winged insects principally abound; when therefore food is scarce, it is not to be wondered at, that these birds should resort to those places where it is almost always to be found in a greater or less quantity. Young swallows, in autumn, are universally observed to roost on trees, and to be extremely fond of congregating: when therefore they have fatigued themselves. with hawking all day about the water, it is highly probable that they should collect in large numbers on the nearest trees; and, besides, those branches that hang over the water are less accessible to rats, weasels, and others of their enemies. Another reason too, on the supposition of their migration, may account for their resorting in autumn to the sides of rivers; for by following the course of the stream, they would more readily find their way to the sea. The supposed fact of swallows having been found in a torpid state under water greatly wants confirmation; it is likely enough, indeed, that they may have been drowned, while roosting, by the rising tide, and been fished up a few hours after, possibly, even while in a state of suspended animation; but their internal structure wholly unfits them for existing for any length of time immersed in water. A more probable opinion than the former is, that those species of swallows above mentioned retire like bats to caverns and other sheltered places during the cold weather, MIGRATION OF SWALLOWS. 425 where they pass their time in a torpid state, except when, revived by a fine day or two, they are induced by hunger to make their appearance in the open air; for it is a known fact, and one that happens almost every year, that a week of tolerably mild weather in the middle of winter never fails to bring out a few swallows, who disappear again on the return of the frost. There are also a few sufficiently authenticated instances of swallows having been found torpid in the shafts of old coal-pits and cliffs by the sea-side. These facts, as far as they go, are conclusive; namely, that some individuals of these species pass the winter in this country in a torpid state; but the instances are by no means sufficiently numerous to preclude the necessity of disposing of the main body in another way; for from their multitudes, if they all never quitted this country, it ought to be by no means an uncommon thing to discover them in their winter abodes; especially as of late years they have been accurately searched for, and the holes of the sand-martins have been repeatedly laid open without the smallest success. Concerning the third hypothesis, the migration of the swallow tribes, it may be observed, that all the birds of this genus are far better flyers than many others whose migration is universally allowed, and that the deficiency of food is a very sufficient motive to induce them to retreat to warmer climates;-that the sudden appearance in spring of the main body, and their disappearance in autumn, together with the occasional appearance of a few during mild weather in the winter months, speaks loudly in favour of migration. But there are yet other more decisive facts to be related in proof of this opinion. Mr. White, one of the most accurate observers that this country has produced, in his "Natural History of Selborne," says, "If ever I saw any thing like actual migration, it was last Michaelmas day. I was travelling, and out early in the morning; at first there was a vast fog, but by the time that I was got seven or eight miles towards the coast, the sun broke out into a delicate warm day. We were then on a large heath or common, and I could discern, as the mist began to clear away, great numbers of swallows (hirundines rustica), clustering on the stunted shrubs and bushes, as if they had roosted there all night. As soon as the air became clear and pleasant they were all on the wing at once; and by a placid and easy flight, proceeded on southwards toward the sea; after this I did not see any more flocks, only now and then a straggler." Having thus launched our swallows, let us follow them in their course across the sea. In the spring of the year, Sir Charles Wager, on his return up channel from a cruise, during some very stormy weather, as soon as he came within soundings, fell in with a large flock of swallows, which immediately settled like a swarm of bees on his rigging; they were so tired, as to suffer themselves to be taken by hand, and so much emaciated from the long continuance of heavy gales that they had to contend with, as to be reduced to mere skin and bone. After resting themselves for the night they renewed their flight next morning. Willoughby, the first British ornithologist, during a visit in Spain, observed multitudes of half-starved swallows in the province of Andalusia, on their progress to the south. And the brother of Mr. White before mentioned, who resided a considerable time at Gibraltar, had ocular demonstration during the spring and autumn, of the migration of birds across the Straits, among which were myriads of the swallow tribe, and many of our soft-billed birds of passage. In passing these straits, they scout and hurry along in little detached parties of six or seven in a company, and sweeping low just over the land and water, direct their course to the opposite continent at the narrowest passage that they can find. They usually slope across the bay to the southwest, and so pass over to Tangier. From all the above considerations it seems to be pretty evident that swallows do not spend the winter under water that a few, probably some of the later broods, remain with us during the winter, for the most part in a state of torpidity; but that the main body migrates across the Channel to Spain, and thence at Gibraltar, passes to the northern shores of Africa, returning by the same road, in the spring, to Great Britain. When Autumn scatters his departing gleams, MUSIC OF THE WOODS. The feathered eddy floats; rejoicing once, With other kindred birds of season, there THOMSON. 427 Beside the swallow tribe, many other of the soft-billed birds that feed on insects, disappear on the approach of cold weather. To judge from their diminutive size and feebleness of wing, it would scarcely be imagined that these could possibly migrate. It is probable, indeed, that numbers of them are annually lost in attempting to cross the sea, but from the circumstance of their having been actually seen crossing the Straits of Gibraltar to Africa late in autumn, and returning northward early in spring; and from there being no instance on record of their having been seen during our winters, either in a state of torpidity, or roused into activity by a warm day, there seems no reason to doubt the reality of their migration. On the other hand, some birds at this season arrive from still more northerly countries to spend the winter with us. The fieldfare and redwing, whose departure was mentioned in March, return about the end of September; at which time also an internal migration takes place of the ringouzel from the mountains of Wales, Scotland, and the north of England, to the southern coast and other sheltered situations. These three species feed chiefly on the berries with which our woods and hedges are plentifully stored the greater part of the winter. The wood-owl now begins to hoot, the stone-curlew to clamour; and those sweet and mellow-toned songsters, the woodlark, thrush, and blackbird, commence at this time their autumnal music. About the middle of the month the common snake sloughs or casts its skin; it appears to part with its whole external covering, even the outer coat of the eyes scales off, and is left in the head of the slough like a pair of spectacles. While the snake undergoes this operation, he entangles |