Creator. Dr. Derham observes two circumstances remarkable in this migration: the first, that these untaught, unthinking creatures, should know the proper times for their passage, when to come, and when to go; as also, that some should come when others go. No doubt, the temperature of the air as to heat and cold, and their natural propensity to breed their young, are the great incentives to these creatures to change their habitations. But why should they at all change their habitations? And why is not some certain place to be found, in all the terraqueous globe, that, all the year round, can afford them convenient food and habitation ?—The second remarkable circumstance is, that they should know which way to steer their course, and whither to go. What instinct is it that can induce a poor foolish bird to venture over vast tracts of land and sea? If it be said, that by their high ascents into the air, they can see across the seas; yet what shall instruct or persuade them, that another land is more proper for their purpose than this? That Great Britain, for instance, should afford them better ac-commodation than Egypt, the Canaries, Spain, or any of the other intermediate countries1? The birds of passage, moreover, are all peculiarly accommodated, by the structure of their parts, for long flights; and it is remarked, that, in their migrations, they observe a wonderful order and polity: they fly in troops, and steer their course, without the aid of a compass, to vast unknown regions. The flight of the wild geese, in a wedge-like figure, has been often observed; to which it is added, by the natural historian of Norway, that the three foremost, who are the soonest tired, retreat behind, and are relieved by others, who are again succeeded by the rest in order2. But this circumstance has been ob served, many ages before, by Pliny, who describes certain birds of passage flying in the form of a wedge, and spreading wider and wider; those be hind resting upon those before, till the leaders, being tired, are, in their turn, received into the rear. 'Wild ducks and cranes (says the abbé de la Pluche) fly at the approach of winter, in quest of more favourable climates. They all assemble, at a certain day, like swallows and quails. They decamp at the same time, and it is very agreeable to observe their flight. They generally range themselves in a long column like an I, or in two lines united in a point like a V reversed.' And thus, as Milton says, Ranged in figure wedge their way. The duck or quail that forms the point (adds the abbé) cuts the air, and facilitates a passage to those that follow: but he is charged with this commission only for a certain time, at the conclusion of which he wheels into the rear, and another takes his post?? And thus again, as Milton observes, With mutual wing Easing their flight. It has been observed of the storks, that, for about the space of a fortnight before they pass from one country to another, they constantly resort together, from all the circumjacent parts, to a certain plain, and there forming themselves once every day into a dou-wanne (according to the phrase of the people) are said to determine the exact time of their departure, and the places of their future abode3. 1 A tergo sensim dilatante se cuneo porrigitur agmen, largèque impellenti præ betu auræ. Colla imponunt præcendentibus: fessos duces ad terga recipiunt. Nat. Hist. 1. x. Where the Rhine loses its majestic force The stork assembly meets; for many a day, Wheeled round and round, in congregation full THOMSON. 6 Mr. Biberg, an ingenious naturalist of Sweden, has observed, that the starling, finding, after the middle of summer, that worms are less plentiful in that country, goes annually into Scania, Germany, and Denmark. The female chaffinches, every winter, about Michaelmas, go in flocks to Holland; but as the males stay in Sweden, the females come back next spring, except such as choose to breed no more. In the same manner, the female Carolina yellow-hammer, in the month of September, while the rice on which she feeds is laid up in granaries, goes toward the south, and returns in the spring to seek her mate. Our aquatic birds (continues he) are forced by necessity to fly toward the south every autumn, before the water is frozen. Thus we know, that the lakes of Poland and Lithuania are filled with swans and geese every autumn, at which time they go in great flocks, along many rivers, as far as the Euxine Sea. But in the beginning of spring, as soon as the heat of the sun molests them, they return back, and go again to the northern ponds and lakes, in order to lay their eggs. For there, and especially in Lapland, there is a vast abundance of gnats, which afford them excellent nourishment, as all of this kind live in the water before they get their wings. Mr. Biberg proceeds to enumerate many other birds that migrate to different regions; and he then adds: By these migrations, birds become useful to many different countries, and are distributed over almost all the globe; and I cannot here forbear expressing my admiration, that all of them exactly observe the times of coming and going, and that they never mistake their way. The principal food of the birds of passage, while in Great Britain, is the fruit of the white thorn, or haws, which hang on our hedges in winter in prodigious plenty; but where they breed, and seem to be most at ease, as in Sweden, &c. there are no haws; nor indeed in many of the countries through which they journey on their way: so that it is evident they change their food in their passage. The manner in which the birds of passage journey to their southern abodes is supposed to vary, according to the different structure of their bodies, and their power of supporting themselves in the air. The birds with short wings, such as the redstart, blackcap, &c. though they are incapable of such long flights as the swallow, or of flying with such celerity, yet may pass to less distant places, and by slower movements. Swallows and cuckoos may perform their passage in a very short time; but there is for them no necessity for speed, since every day's passage affords them an increase of warmth, and a continuance of food. Swallows are often observed, in innumerable flocks, on churches, rocks, and trees, previous to their departure hence; and Mr. Collinson proves their return here, perhaps in equal numbers, by two curious relations of undoubted credit; the one communicated to him by Mr. Wright, the master of a 1 Biberg On the Economy of Nature, in Stillingfleet's Miscellaneous Tracts. ship, and the other by admiral Sir Charles Wager. Returning home (says Sir Charles) in the spring of the year, as I came into soundings in our channel, a great flock of swallows came and settled on my rigging; every rope was covered; they hung on one another like a swarm of bees; the decks and carving were filled with them. They seemed almost famished and spent, and were only feathers and bones; but, being recruited with a night's rest, they took their flight in the morning.'-This apparent fatigue proves, that they must have had a long journey, considering the amazing swiftness of these birds; so that, in all probability, they had crossed the Atlantic ocean, and were returning from the shores of Senegal, or other parts of Africa.-But the state of the swallow-tribes, when they are no longer seen in our northern regions, has given rise to a curious controverted question among naturalists, of which I shall treat in my next paper. In the mean time, my readers, I am persuaded, will be pleased with the following beautiful poetical welcome to these birds, on their re-appearance in the Spring, by the contemporary and friend of Shenstone and Collins: At length the winter's surly blasts are o'er ; And see, my Delia, see o'er yonder stream, The stranger-swallows take their wonted way. No tempest on my shed its fury pours, |