KNOWLEDGE FOR THE PEOPLE: OR, THE PLAIN WHY AND BECAUSE.
Part IV.—Zoology—Birds.
This portion illustrates the Economy of Birds, with a few of the most attractive varieties, under European and British, and Foreign Birds. We quote from the "General Economy;" premising that the present Part contains about 250 such illustrations, or Why and Because.
Why are birds usually classed according to the forms of their bills and feet? Because those parts are connected with their mode of life, food, etc., and influence their total habit very materially. Blumenbach.
Why have birds little power of suction?
Because of the narrowness and rigidity of their tongue; as may be seen when they drink, having to hold up their heads, and depend upon the weight of the water for transmitting it into the craw.—Rennie.
Why are birds said to be "poised" in the air?
Because the centre of gravity of their bodies is always below the insertion of their wings, to prevent them falling on their backs, but near that point on which the body is, during flight, as it were, suspended. The positions assumed by the head and feet are frequently calculated to accomplish these ends, and give to the wings every assistance in continuing the progressive motion. The tail also is of great use, in regulating the rise and fall of birds, and even their lateral movements.—Fleming.
Why do birds fly?
Because they have the largest bones of all animals, in proportion to their weight; and their bones are more hollow than those of animals that do not fly. Air-vessels also enable them to blow out the hollow parts of their bodies, when they wish to make their descent slower, rise more swiftly, or float in the air. The muscles that move the wings of birds downwards, in many instances, are a sixth part of the weight of the whole body; whereas, those of a man are not in proportion one-hundredth part so large.
Why are birds covered with feathers?
Because, by this addition to the non-conducting appendices of the skin, birds are enabled to preserve the heat, generated in their bodies, from being readily transmitted to the surrounding air, and carried off by its motions and diminished temperature.—Fleming.
Why are the strongest feathers of birds in the pinions and tail?
Because the pinion-feathers may form, when the wing is expanded, as it were, broad fans, by which the bird is enabled to raise itself in the air and fly; whilst its tail feathers direct its course.—Blumenbach.
Why do birds moult?
Because they may be prepared for winter; this change being analogous to the casting of hair in quadrupeds. During summer, the feathers of birds are exposed to many accidents. Not a few spontaneously fall; some of them are torn off during their amorous quarrels; others are broken or damaged; whilst, in many species, they are pulled from their bodies to line their nests. Hence, their summer dress becomes thin and suitable. Previous to winter, however, and immediately after incubation and rearing of the young is finished, the old feathers are pushed off in succession by the new ones, and thus the greater part of the plumage of the bird is renewed.—Fleming.
Why do birds sing?
Because of the receptacles of air already mentioned but particularly by the disposition of the larynx, which in birds is not, as in mammifera and amphibia, placed wholly at the upper end of the windpipe; but, as it were, separated into two parts, one placed at each extremity. Parrots, ravens, starlings, bullfinches, &c., have been taught to imitate the human voice, and to speak some words: singing birds also, in captivity, readily adopt the song of others, learn tunes, and can even be made to sing in company, so that it has been possible actually to give a little concert by several bullfinches. In general, however, the song of birds in the wild state appears to be formed by practice and imitation.—Blumenbach.
Why do the notes of different species of birds vary?
Because, probably, of the structure of the organs of each species enabling them more easily to produce the notes of their own species, than those of any other, and from the notes of their own species being more agreeable to their ears. These conditions, joined to the facility of hearing the song of their own species, in consequence of frequenting the same places, determine the character of the acquired language of the feathered tribes.—Fleming.
Why are birds equally dispersed in spring over the face of the country?
Because, during that amorous season, such a jealousy prevails between the male birds, that they can hardly bear to be seen together in the same hedge or field. Most of the singing and elation of spirits, of that time, seem to be the effect of rivalry and emulation.—G. White.
Why is August the most mute month, the Spring, Summer, and Autumn through?
Because many birds which become silent about Midsummer, reassume their notes in September; as the thrush, blackbird, woodlark, willow-wren, &c.—G. White.
Why do birds congregate in hard weather?
Because, as some kind of self-interest and self-defence is, no doubt, their motive, may it not arise from the helplessness of their state in such rigorous seasons; as men crowd together, when under great calamities, they know not why? Perhaps approximation may dispel some degree of cold; and a crowd may make each individual appear safer from the ravages of birds of prey and other damages.—G. White.
Why do we so often fail in rearing young birds?
Because of our ignorance of their requisite food. Every one who has made the attempt, well knows the various expedients he has resorted to, of boiled meats, bruised seeds, hard eggs, boiled rice, and twenty other substances that Nature never presents, in order to find a diet that will nourish them; but Mr. Montagu's failure, in being able to raise the young of the curl-bunting, until he discovered that they required grasshoppers, is a sufficient instance of the manifest necessity there is for a peculiar food in one period of the life of birds.—Knapp.
Why have most noctural birds large eyes and ears?
Because large eyes are necessary to collect every ray of light, and large concave ears to command the smallest degree of sound or noise.
Why do stale eggs float upon water?
Because, by keeping, air is substituted for a portion of the water of the egg, which escapes.—Prout.
Why has the breast-bone of all birds which fly, a long ridge or keel?
Because muscles are attached to it, to facilitate their flight.
Why is the plumage of aquatic birds kept dry?
Because the small feathers next the bird fall over each other like the tiles of a roof, and thus throw off the water.