A sentinel heron that has been standing watchful on one leg rises, and flaps languidly away down the river reach. The consumptive figure of the gaunt bird stands by the stream through all weathers. He knows not times nor seasons, and is a great poacher. In the wind, when taking his lone stand, his loose fluttering feathers look like drift-stuff caught in the bushes. He reminds one of the consumptive, but, unlike him, has wonderful powers of digestion, and withal an immense capacity for fish. Woe to the luckless mort or trout that comes within reach of his formidable pike, or to the attacking peregrine that he attempts to impale on his bill. The heron is essentially a wanderer, and, like Wordsworth's immortal leech-gatherer, he roams from pond to pond, from moor to moor. Herons come and go by the same routes; and night after night have we flushed our fisher from the selfsame shallow. The peculiarly wild whistle of the curlew comes from out the night sky, and swifts screech for an hour after darkness has fallen. We are now by the covert side, and a strange churring sound comes from out the darkened glades. Waiting silently beneath the bushes, it approaches nearer and nearer until a loud flapping is heard in the bushes. The object approaches quite closely, and it is seen that the noise is produced by a large bird striking its wings together as they meet behind. Even in the darkness it may be detected that each wing is crossed by a definite white bar. The bird is a goatsucker or nightjar. Had we it in our hand, we should see that it was a connecting link between the owls and the swallows, having the soft plumage and noiseless flight of the one and the wide gape of the other. The object of the noise it produces is probably to disturb from the bushes the large nightflying moths upon which it feeds. The name goatsucker the bird has from a superstitious notion that it sucks goats and cows--a myth founded probably upon the fact of its wide gape. It is certain that these birds may often be seen flitting about the bellies of cattle as they stand knee-deep in the summer pastures. The reason of this is obvious, as there insect food is always abundant. Unless disturbed, the nightjar rarely comes abroad during the day, but obtains its food at twilight and dusk. Upon the limestone-covered fells it conforms marvellously to its environment, it being almost impossible to detect its curiously mottled plumage as it basks upon the grey stones, not more still than itself. Here it lays its two eggs, often without the slightest semblance of a nest, frequently upon the bare rock. Quite a peculiar interest attaches to the bird, inasmuch as it is furnished with a remarkable claw, the use of which is guessed at rather than known. This claw is serrated on its inner edge, and from actual experiments made upon nightjars in captivity, we should surmise that its use is to free the long whiskers from the soft, silvery dust which usually covers the bodies of night-flying moths.