Hence it is in the winter that the picturesque character of the flight of birds is particularly noticeable. In summer, and in autumn, before the fall of the leaf, birds are partially concealed by the foliage of trees, so that the manner of their flight does not become so readily apparent. But in winter, if we start a flock of birds from the ground, we can hardly avoid taking notice of all the peculiarities of their movements. I have alluded to the descent of Snow-Buntings upon the landscape as singularly picturesque; but the motions of a flock of Quails, when suddenly aroused from a thicket, are not less so. When a Pigeon, or any other bird with strong and large wings, takes flight, the motions of its wings are not vibratory, and its progress through the air is so rapid as to injure the pleasing effect of its motions, because we obtain no distinct perception of the bird during its flight. It is quite otherwise with the Quail. The body of this bird is plump and heavy, and his wings are short, and have a peculiar concavity of the under surface when expanded; their motions are very rapid, and, having but little sweep, the bird seems to sail on the air, carried along by a gentle but rapid vibration of the wings, which describe only a very small arc of a circle. Hence we observe the entire shape of the bird during its flight. The Partridge, and other gallinaceous birds, fly in a similar manner; but, on account of their larger size, their motions are less attractive. The Humming-Bird has proportionally larger wings than the Quail, and, when flying, his wings describe almost a complete circle in their rapid vibrations. If we look upon one during his flight, he seems to have no wings, but rather to be encircled by a semi-transparent halo. There are other birds that seem to be wings only, their bodies being hardly perceptible, on account of their small proportional size; such are the Swallow, the Pigeon, the Cuckoo, and the Night-Hawk. Birds of prey are remarkable for their steady and graceful flight; the motion of their wings is slow, while, like the Pigeon, they are capable of propelling themselves through the air with great rapidity. The circumgyrations of a Hawk, when reconnoitring far aloft in the air, are singularly graceful. The flight of the Crow and the Raven is slow and apparently difficult, and they are easily overtaken and annoyed by the King-Bird and other small birds. They are not formed, like the Falcon, to catch their prey upon the wing, and, though their wings are large and powerful, they are incapable of performing those graceful and difficult evolutions which we observe in the flight of birds of prey. The flight of Herons resembles that of the Raven. Small birds, with the exception of a few species, move in an undulating course, alternately rising and sinking. Birds that move in this manner are, I believe, incapable of making a long journey on the wing without rest, and commonly perform their migrations by short daily stages.