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FEATHERS OF WATER-BIRDS.
with oils and metallic substances in very minute portions ; but in the down and the light-coloured feathers it is nearly pure.
“ The under part of the clothing feathers, and also a small portion of almost all feathers near the tube or barrel, consists of down, but the exposed surfaces, even of the softest feathers, are smoothed so as to throw off the water. This
is the case even in those water-birds which pass the greater part of their time with the under part of their body immersed in water. On them, the down is abundant in proportion as the habits of the birds expose them to cold; and the external surface is waterproof, from its glossy texture, and (possibly ?) also from the oil with which the bird anoints it by means of its bill: but in all birds there is an external surface, adapted to prevent decomposition, and an inner downy matter, as a protection against the changes of temperature. The down is partly on the rootends of the feathers, and partly on the skin in the intervals between them, but the material is in all cases substantially the same; the difference is in the form, or in the colour, which generally approaches nearer to white in the down than in the feathers. When the bird remains all the year round in situations where there are great differences in the heat of the seasons, the down increases in quantity during winter; and when birds of a warmer climate are domesticated in colder one, they become more downy. The form which the down assumes is often characteristic of the habits of the bird. In the ostrich there is none; in some birds it is a mere tuft at the origin of the webs, in others it is a second feather originating there; and there are all the intermediate states in different birds, and very considerable seasonal differences in the same bird.
“Different birds find their food in different states, both of the atmosphere and the waters ; and very beautiful corresponding differences in their plumage may be traced. The plumage upon the raven, which braves the storm in the wilds, is very different from that of the gallinaceous or poultry races, which a slight shower drives to their cover or their perch; and ducks and other water birds, which seek their food peaceably on the banks, or by swimming in the shallow waters, have very different plumage from those which hawk about on the wing, in order to catch what the troubled sea brings to the surface. If the habit of the bird be to steal softly on its prey, then the feathers are fined off to exceedingly delicate points, so that it can glide silently through the air.
“The feathers of birds, while they remain perfect and firm in their connection, are really parts of a living animal, and as such they must be regarded as organs of feeling. They do not, probably, in themselves feel pain, but they are in intimate connection with parts which do. The epidermis in no animal appears to feel pain, even in those parts of the animal which are regarded as being more immediately the organs of sensation ; but they very speedily transmit impressions to the parts that do feel. It is the same with hair, and with all the appendages of the cuticle, such as nails, claws, hoofs, and horns. The horse feels his footsteps in the dark, even when his hoofs are shod with iron; and he
SENSE OF FEELING IN FEATHERS.
feels not only the touch of a wall, a gate, or any other obstacle, but he feels the difference which such objects cause in the resistance of the air, and that enables him to avoid touching them.
“ The horse feels his way by means of the hair, and birds must in like manner often feel their way by their feathers. Such must be habitually the case with owls and other nocturnal birds, which can fly darkling through thick woods and other intricate places; and though the owls have their eyes directed forwards, and not laterally, as many other birds have, they are by that means less capacitated for avoiding by sight, even admitting that they can see with the smallest possible portion of light, those obstacles which it would be the most awkward to encounter-those of course which would injure, entangle, or impede their wings. If one wing were to come in contact with a tree, or even with a leaf, the bird would be upset, as certainly as a man is, when in walking heedlessly he places one foot over a pit or ditch while the other is on the ground.
“ The necessity of feeling with the feathers is not confined to nocturnal birds, but is essential to the safety of all the winged tribes, the feathers must therefore always be in a state of great perfection. Now though the shafts of many feathers and the larger ribs of the webs or bones of not a few, are of considerable substance and strength, all feathers are subdivided till the ultimate ramifications are exceedingly minute. Consequently, they produce very large surfaces to the air, in proportion to the quantities of matter they contain.
"Feathers are thus very much exposed to atmospheric action, which dries them, and renders them unfit for the functions that are required of them. They are also apt to be broken or torn in the flights, the wars, and the labours of their owners. They are therefore periodically shed and reproduced; and the reproduction usually takes place in such a way, so that the bird shall be in best feather at the very time when it has the greatest labour to perform.
“ The resident native birds of countries where the heat of the year is comparatively uniform, moult gradually, same may be said of those that have their haunts in regions that are always cold, and where the food is comparatively
limited. Such birds are seldom so denuded of feathers as to be unfit for pretty vigorous flight. Birds which migrate from region to region moult more periodically ; and in places where the migration is extensive, it will perhaps be found, upon further examination, that the bird moults twice in a year, though in most instances the spring moult is less general than the autumnal one, being in many birds, the males especially, rather a change of colour than of all the feathers. Birds which migrate polarly, or for the purpose of breeding, generally receive their nuptial colours, if not their plumage, after they arrive ; but when they migrate equatorially, they change their plumage before they begin their journey. The vernal change in the plumage of birds is owing to the same cause as the change of their voices, from the chirp or cry to song; and in a state of nature the two cease together.
MIGRATION OF BIRDS. Birds, generally speaking, says Cuvier, appear to belong more to the air than to the earth. They constitute moving republics, which traverse the atmosphere at stated periods, in large bodies. These bodies perform their aërial evolutions like an army, crowd into close column, form into triangle, extend in line of battle, or disperse in light squadrons. The earth and its climates have less influence on them than on quadrupeds, because they almost always live in similar degrees of temperature, passing the winter in hot climates, and the summer in cold. The continual interchange of birds establishes a communication between all countries, and keeps up a sort of equilibrium of life. The bird passing in summer from the equinoctial climates to the cold regions of the north, and again in winter from the poles towards the equator, knows, by an admirable instinct, the winds and the weather which are favourable to his voyage. He can long foresee the approach of frost, or the return of spring, and learns the science of meteorology from the element in which he almost constantly lives. He needs no compass to direct his course through the empire of the clouds, the thunder, and the tempest; and while man and beast are creeping on the earth, he breathes the pure air of heaven, and soars
MIGRATION OF BIRDS.
upwards nearer to the spring of day. He arrives at the term of his voyage, and touches the hospitable land of his destination. He finds there his subsistence prepared by the hand of Providence, and a safe asylum in the grove, the forest, or the mountain, where he revisits the habitations he had tenanted before, the scene of his former delights, the cradle of his infancy. The stork resumes his ancient tower, the nightingale the solitary thicket, the swallow his old window, and the redbreast the mossy trunk of the same oak in which he formerly nestled. All the volatile species which disappear in the winter do not, therefore, change their climate. Some retire into remote places, to some desert cave, some savage rock, or ancient forest, from whence they sally at the close of winter, and spread themselves through the country.
Other families of birds do not, properly speaking, emigrate. They content themselves with approaching the southern climates, in proportion as they are pursued by the cold. The species called erratic, such as the greenfinches of the Ardennes, larks, ortolans, other frugivorous races, and especially parrots, go in troops begging, as it were, their subsistence on the passage.
Others follow the track of cultivation, and spread themselves in proportion with the habitations of men.
Of the birds which migrate every year, some depart in autumn and return in spring, while others depart in spring and return in autumn. Our insectivorous races, and many granivorous, finding nothing at the beginning of winter but a soil deprived of its productions, presenting everywhere the image of desolation and death, are necessitated to betake themselves to more favoured climes. Those which, through negligence or weakness, remain behind, drag out a miserable existence, and constantly perish from famine in the midst of frost and snow.
As our summer birds abandon us towards the close of autumn, we receive, at the same time, fresh supplies of feathered hordes from the populous north. When the weather grows dull, we see passing through the misty
* How truly do these wretched little birds verify the old proverb that “ God takes care of those who take care of themselves.”—ED.