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?