The flight of the Stone Chat is remarkable, owing to the fact that, at whatever height the perch may be from which it starts, the bird invariably sinks towards the ground, close to the surface of which it always flies, in a series of short, undulating lines. At the approach of the breeding season this mode of flight is changed, and the bird then entertains itself and its mate by repeatedly soaring into the air to a height of some twenty or thirty feet, singing as it goes, and then descending precipitately, to end its joyous song upon its favourite perch. When standing upon a stone or rock, it holds its body erect, shakes its tail, and, should anything unusual catch its eye, at once commences bowing repeatedly. This strange habit has given rise to its Spanish name of the "Sacristan," in allusion to the genuflexions practised by the monks. The voices of all the species we have described are loud and peculiar, but by no means pleasing. Of their performance, however, it may be said that what is wanting in quality is made up by the energy and persistency with which their song is poured out, not only from daybreak to sunset, but long after night has closed in. The nest, which is for the most part built in holes and fissures of rocks and stones, or occasionally in hollow trees, is carefully concealed from view. Its dense roughly-made exterior is formed of fibres, grass, and stalks, lined thickly and warmly with wool, hair, or feathers; the eggs, from five to seven in number, are of a delicate blueish or greenish white, occasionally, but rarely, spotted with pale yellow. The female hatches her brood with but little assistance from her mate, who perches near, in order to keep a strict watch against the approach of danger, and warns her of its appearance by an anxious cry. But one brood is produced in the season, the first eggs being laid about May; occasionally, however, the female produces two broods. The young remain with the parents till the winter migration, which takes place in September. In March they again return to their native lands. * * * * * The RUNNING WARBLERS (_Dromolæa_) constitute another group of this family, recognisable by the predominance of black in the coloration of their plumage, and by the formation of their comparatively long and much compressed beak, which is broad at its base, and very decidedly curved and hooked at its extremity. The wings are long and pointed. THE WHITE-TAILED WHEATEAR.