Because, could we find a people, from Japan to the Pole, whose progress in mind has been stationary, without increase of idea, from national prejudice or impossibility of communication with others, we should probably find little or no alteration in the original language of that people : so, by analogy of reasoning, the animal having no idea to prompt, no new want to express, no converse with others - for a note caught and uttered, is merely like a boy mocking a cuckoo; so no new language is acquired. This fact is also corroborated by various little scraps of intelligence scattered through the sacred and ancient writings. With civilized man all is progressive; with animals, where there is no mind, all is stationary. - Knapp.
Because the gizzard, being covered with very strong muscles, by its action, comminutes the food. Other birds, that are carnivorous or piscivorous, have a stomach more resembling that of carnivorous quadrupeds; the digestion of such birds being more accelerated by the gastric juice than by the action of the stomach itself.
Because the summer has been ungenial, the berries have not ripened well, but have been nipped by frost, and hang on the sprays, dark in colour, small, and juiceless in substance.
Because animal food most readily assimilates with the fluids of their bodies, with the least efforts of the digestive powers.
Because the motion of the branches produced by the wind, increases their disposition for sleep. This may be exemplified in the common fowl: for, placing its bill under the wing, even in broad daylight, and swaying it to and fro in the hand for a very short time, will produce sleep ; a beautiful proof of the adaptation of birds to the function. - Jennings.
Because such is the structure of their feet and legs, that the greater the weight upon the muscles, the more firmly the claws grasp whatever they lay hold of.
Because, the instant that it is uttered, we hear the whole flock, though composed of various species, repeat a separate moan, and away they all scuttle into the bushes for safety. - Knapp.
Because it has a membrane (see page 8. ) with which the bird can, at will, cover the pupil of the eye, while the eyelids remain open.
Because fish, the food of the former, are probably but little influenced by season ; while our poor land birds find theirs to be nearly annihilated in some cases.