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EIGHTH WEEK-WEDNESDAY.

HYBERNATION.-BIRDS WHICH PARTIALLY MIGRATE.

THERE are some of the British feathered tribes, which although they do not pass beyond the sea, are yet, to a certain extent, migratory within the bounds of the island. These are chiefly influenced in their change of residence, by the desire of finding a more remote retreat, for the purpose of incubation, or of acquiring a more plentiful supply of food, or, perhaps, in some instances, a more sheltered place of residence during the stormy months. Of these,' says Mr. Rennie, 'may be mentioned in our country, the curlew and golden plover,. which in winter reside chiefly along the shores, while in summer they betake themselves to the inland lakes and moors; the lapwing, which seems to move northwards in winter ; the linnet, which in that season deserts the hilly regions, and approaches the habitations of man; and the dipper, which in summer ascends the streams, towards their sources.'

But it is in continental countries, and especially in America, where interminable forests are mingled with districts, and bounded by regions cultivated by the labour of man, and teeming with crops of grain, that the most remarkable instances of this kind of partial migration take place. The countless multitudes of pigeons in that country, which, at particular seasons, shift their residence in continuous and almost endless flocks, have long been the admiration of travellers. Audubon in his usual graphic manner, describes a flight of this tribe, of which he was an eye witness. 'In the autumn of 1813,' says he, 'I left my house at Henderson, on the banks of the Ohio, on my way to Louisville. In passing over the Barrens, a few miles below Hardensburgh, I observed the pigeons flying from north-east to south-west in greater numbers than I thought I had ever seen them before; and feeling an inclination to count the flocks that

might pass within the reach of my eye in one hour, I dismounted, seated myself on an eminence, and began to mark with my pencil, making a dot for every flock that passed. In a short time, finding the task that I had undertaken impracticable, as the birds poured on in countless multitudes, I rose, and counting the dots then put down, found 163 had been made in twenty-one minutes. I travelled on, and still met more, the farther they proceeded. The air was literally filled with pigeons; the light of noon-day was obscured as by an eclipse; the dung fell in spots, not unlike melted flakes of snow; and the continued buzz of wings had a tendency to lull my senses to repose.' 'Before sunset,' he adds afterwards, 'I reached Louisville, distant from Hardensburgh fifty-five miles. The pigeons were still passing in undimin ished numbers, and continued to do so for three days in succession.' The atmosphere, during this time, was strongly impregnated with the peculiar odour which emanates from the species.'

Though not entirely to the point we are considering, we willingly yield to the temptation of inserting a striking passage which occurs in this account:-'I cannot describe to you the extreme beauty of their aerial evolutions, when a hawk chanced to press upon the rear of a flock. At once, like a torrent, and with a noise like thunder, they rushed into a compact mass, pressing upon each other towards the centre. In these almost solid masses, they darted forward in undulating and angular lines, descended, and swept close over the earth, with inconceivable velocity, mounted perpendicularly, so as to resemble a vast column, and, when high, were seen wheeling and twisting within their continued lines, which then resembled the coils of a gigantic serpent.'

These flights are, doubtless, in search of food, and may throw some light on the nature of the principle by which migrations are influenced, as they are obviously regulated by an impulse, if not observing and intelligent, at least capable of being adapted to new circumstances, and of taking advantage of new discoveries Catesby mentions, that since the

discovery of America has introduced crops of foreign grain into that once savage and uncultivated country, not only have these novel articles of food become the familiar resource of native birds from distant regions, but various species of the winged tribes, naturally strangers to that continent, have, by some means, become aware of the existence of such exotic stores, and arrive annually in numerous flocks, at the proper season, to avail themselves of this new provision for their wants. The rice-bird and the wheat-bird are of this description. The latter, if Catesby's observations be correct, has taken this new course of migration across the sea from the island of Cuba, between one and two hundred miles distant from the nearest point of the mainland, leaving that region immediately after the rice harvest, and alighting in Carolina in time to partake of the rice crop in that latter climate, and afterwards of the ripening wheat in the more northerly plains of Virginia. It is, indeed, but a few years since the wheatbirds first found their way to this latter State, where they now regularly flock at the proper season, in such numbers, as materially to interfere with the gains of the farmer.

This is a very interesting view of the nature of the winged family, and gives rise to some curious and difficult questions. By what means do birds ascertain the introduction of their proper food into these new and distant regions? How do they communicate the information to their fellows, after they have obtained it? And when once known, by what faculty is it perpetuated in the individuals, and transmitted to their posterity? Are we to believe that, like man, they make distant voyages of discovery in search of new stores; that they possess a faculty resembling that of speech, by which they convey a knowledge of the discoveries they have made; and that they are furnished with memories sufficiently retentive, and reasoning powers sufficiently strong, to enable them, from year to year, as the season returns, to profit by the new knowledge they have acquired? This seems to be Catesby's opinion; and it would, doubtless, readily account for these and various other phenomena of a similar nature, which

may occur to the inquiring mind; but it seems to be so inconsistent with what is known of the limited mental powers of birds, that it will not readily be assented to, and we must, probably, look for the true solution in some qualities bearing more resemblance to the admitted faculties of the race. If, however, we attempt to pursue the inquiry farther, we shall, perhaps, here, as in a thousand other instances, land ourselves in perplexity and darkness, and be forced to rest in the humbling conviction, that such knowledge is too high for us. When we become aware that the migratory impulse varies according to circumstances, and is modified by changes in climate or in food, whether dependent on natural causes or on the labours of civilized man, we seem to have acquired a glimmering of something like a principle of reason as applicable to that impulse. But when, on the other hand, we consider the extent to which that reasoning principle must necessarily be carried, before it can account for the phenomena, -when we recollect, that it must include some high powers of memory, reflection, and judgment, as well as considerable geographical knowledge, and an accurate acquaintance with the progress of time, as connected with the changes of the seasons and the ripening of the fruits of the earth, it seems altogether impossible to maintain this ground; and we feel compelled to fall back on our first conclusions, and to resolve the whole, or at least by far the greater part, into a power, the nature of which has hitherto eluded all attempts to analyze it, and our ignorance of which we endeavour to conceal under the name of instinct.

Here, then, we find new cause to look up with awe and adoration to the mysterious but beneficent operations of that unseen, omnipresent Intelligence, who causes, 'the stork in the heaven to know her appointed times, and the turtle, and the crane, and the swallow, to observe the time of their coming.

EIGHTH WEEK-THURSDAY.

HYBERNATION.-MIGRATION OF QUADRUPEDS.

THE care of Providence in securing the subsistence and comfort of quadrupeds in the winter months, is not less remarkable than that which is displayed towards the feathered creation; and the modifications of their hybernating instincts, and of other arrangements, exhibit equal indications of wise and beneficent design. A striking example of that adaptation of propensities to external circumstances, which is to be found characterising the instincts of all the orders of organized beings, occurs among the brute tribes, in the limited extent of their migratory habits. Being destitute of wings, which transport the various species of birds so expeditiously and safely through the air, they cannot leave their native haunts without difficulty and danger, arising from the rugged and intersected nature of the earth to which they are con fined, and the fury of the enemies they would meet with in a journey necessarily tedious, and often unsheltered. Some quadrupeds, however, do possess this instinct in situations favourable for its exercise. In our own island, for example, the stag and the roebuck leave the higher regions on the approach of winter, and seek protection in the more sheltered plains. But it is in continental countries, where larger space is afforded, and where the variety of climate gives freer scope for the development of the principle, that migratory habits are to be chiefly expected, and it is there that they actually exist to the greatest extent. On this subject I shall take leave to quote an interesting passage in Mr. Kirby's Bridgewater Treatise, which occurs under the head of Geographical Distribution of Animals :—

'We are next to consider those migrations that take place periodically, and usually at certain seasons of the year; the general intention of which appears to be a supply of food, and often a temperature best suited to reproduction; Provi

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