If it is difficult to satisfy oneself as to the way in which a bird alights, it is no less so to detect its movements in taking wing. Most of us must have seen sparrows making this effort from the road, thousands of times. But ask of anyone, How is it done? The act takes place so quickly that the eye cannot follow its execution. And what is true of the sparrow is true of most birds. But there are some where this is not the case. Many water-birds, the cormorant, for example, get under way but slowly, and with evident effort. They flap along the surface for some distance before they gain sufficient impetus to lift them into the air. And there are many long-winged, short-legged birds which can rise from a level surface only with great difficulty, or not at all. The swift is one of these, for its legs are excessively short. The albatross is another: and this is true, indeed, of many of the petrel-tribe. The puffin, again, seems unable to rise on the wing from the ground. It appears invariably to run along until it reaches the edge of cliff which lodges its burrow, and then, as it were, throw itself over the edge. The heron, when springing into the air, stretches his long neck out to its fullest extent, and presents a pair of dangling legs, well shown in one of our coloured Plates, but when once fully on the way its pose entirely changes, the neck being drawn in and the legs thrust out backwards. Flight does not always mean progress through the air. Most birds can, at need, arrest their course, and hang, as it were, suspended in the air. In the beautiful coloured plate, representing the chaffinch hovering over its half-fledged young, and in that of the kingfisher and its young, this form of "hovering" flight can be seen. But the greatest of all exponents in the art of hovering is the kestrel, known also, for this very reason, as the "windhover." It is most fascinating to watch this bird hang, as it were, from the clouds, motionless, yet with quivering wings, as he scans the ground below in his search for some unsuspecting mouse. It is hard, indeed, to say which is the more wonderful, this power of remaining stationary for comparatively long periods in the air, or the surprising powers of sight which this bird possesses. During these hovering movements, always head to wind, it will be noted, the tail plays a very important part, being spread to its extremest limit, and at the same time thrust forward beneath the body. In some birds this forward movement is more marked than in others. And this because such birds possess a somewhat more flexible spine, there being a certain amount of "play" where the vertebræ of the loins join the welded mass of vertebræ which lie between the bones of the hip-girdle.