The true nocturnal birds, of which the Owl and the Whippoorwill are conspicuous examples, are distinguished by a peculiar sensibility of the eye, that enables them to see clearly by twilight and in cloudy weather, while they are dazzled by the broad light of day. Their organs of hearing are proportionally delicate and acute. Their wing-feathers also have a peculiar downy softness, so that they fly without the usual fluttering sounds that attend the flight of other birds, and are able to steal unawares upon their prey, and make their predal excursions without disturbing the general silence of the hour. This noiseless flight is very remarkable in the Owl, as may be observed, if a tame one be allowed to fly about a room, when we can perceive his motions only by our sight. It is a fact worthy of our attention, that this peculiar structure of the wing-feathers does not exist in the Woodcock. Nature makes no useless provisions for her creatures; and hence this nocturnal bird, which obtains his food by digging into the soil, and gets no part of it while on the wing, has no need of this contrivance. Neither stillness nor stealth would assist him in securing his helpless prey. Among the nocturnal birds, the most notorious is the Owl, of which there are many species, varying from the size of an Eagle down to the little Acadian, which is no larger than a Robin. The resemblance of the Owl to the feline quadrupeds has been a frequent subject of remark. Like the cat, he sees most clearly by twilight or the light of the moon, seeks his prey in the night, and spends the principal part of the day in sleep. The likeness is made stronger by his tufts of feathers, that correspond to the ears of the quadruped,--by his large head,--his round, full, and glaring eyes, set widely apart,--by the extreme contractility of the pupil,--and in his manners, by his lurking and stealthy habit of surprising his victims. His eyes are partially encircled by a disk of feathers that yields a peculiarly significant expression to his face. His hooked bill turned downwards, so as to resemble the nose in a human countenance, the general flatness of his features, and his upright position, give him a grave and intelligent look; and it was this expression that caused him to be selected by the ancients as the emblem of wisdom, and consecrated to Minerva. The Owl is remarkable also for the acuteness of his hearing, having a large ear-drum, and being provided with an apparatus by which he can exalt this faculty, when under the necessity of listening with greater attention. Hence, while he is silent in his own motions, he is able to perceive the least sound from the motion of any other object, and overtakes his prey by coming upon it in silence and darkness. The stillness of his flight is one of the circumstances that add mystery to his character, and which have assisted in rendering him an object of superstitious dread.