Swallows arrive in this country about the middle of April, and about a month later proceed to build their nests in the chimneys of houses and on the rafters of barns and outhouses. The nest is basin-shaped and open at the top; it is chiefly composed of mud, which the birds collect on the ground, place in position, and allow to dry. Short straws are used to bind the mud together, and the nest is lined with soft grass and feathers. The hen lays from 4 to 7 eggs, which are a translucent white, with reddish-brown or grey markings. The first brood of young is usually hatched about the end of June, but a second or even a third brood may be raised before the parents depart for the south. Gilbert White[22] gives the following charming account of the training of young swallows: “For a day or two they are fed on the chimney-top, and then are conducted to the dead, leafless bough of some tree, where, sitting in a row, they are attended with great assiduity, and may then be called perchers. In a day or two more they become flyers, but are still unable to take their own food; therefore they play about near the place where the dams are hawking for flies; and, when a mouthful is collected, at a certain signal given, the dam and the nestling advance, rising towards each other, and meeting at an angle; the young one all the while uttering such a little quick note of gratitude and complacency, that a person must have paid very little regard to the wonders of Nature that has not often remarked this feat.” When the young bird has learnt to feed itself “it at once associates with the first brood of house-martins; and with them congregates, clustering on sunny roofs, towers, and trees.... All the summer long is the swallow a most instructive pattern of unwearied industry and affection; for from morning to night, while there is a family to be supported, she spends the whole day in skimming close to the ground, and executing the most sudden turns and quick evolutions.... When a fly is taken a smart snap from her bill is heard, resembling the noise at the shutting of a watch case; but the motion of the mandibles is too quick for the eye.”
The swallow drinks whilst flying, sipping the water from the surface of pools. Its song is a delicate and pleasing warble, which is uttered both at rest and during flight. The voice becomes a squeak when the bird is alarmed or angry. Just before the autumn migration, swallows perch in crowds on roofs, hedges, and the branches of trees. They leave for Africa about the beginning of October.
The house-martin may be distinguished from the swallow by the patch of white upon the upper tail-coverts, and by its feathered toes. Like the swallow, it arrives in this country about the middle of April. The birds soon begin to repair their old nests and to construct new ones under the eaves of houses. The nest is largely composed of clay or mud, which the birds collect from damp places in the road, etc., place in position against the wall, and allowed to harden. The completed nest is somewhat bag-shaped, having only a small hole at the top; it is lined with soft grass. The eggs are white, without spots. It is worthy of notice when a wild bird lays white eggs, they are hidden from sight by the shape or position of the nest, as in the case of the martins, or the nest is built in an inaccessible place. Exposed eggs are usually made more or less inconspicuous by being coloured or spotted. House-sparrows ([Fig. 208]) have often been known to expel the defenceless martins from their nests, and to lay their own eggs therein. The eggs of the sparrow may be recognised by their grey colour, and by the brown blotches with which they are marked.
The structure of the martin, like that of the swallow, is admirably adapted to a life in the air, and to a diet of flying insects—the bird having powerful wings, small and weak feet, and a soft and short but widely-opening beak. House-martins leave us about the beginning of October.
The sand-martin is distinctly smaller than either the swallow or house-martin, and it may be further distinguished from them by the “mouse-colour” of its upper parts. It usually arrives in this country about a fortnight in advance of its two relatives, and also departs before them, leaving in August or September. These birds live in colonies in tunnels which they excavate in banks or friable cliffs ([Fig. 203])—generally in the near vicinity of water. The excavation may be three feet in length; it slopes slightly upwards to the nest (which is placed at the end of the tunnel), in order that rain water may not collect in it. The eggs are pure white, and five or six in number. The birds are exclusively insectivorous; they do not sing, but utter a little twitter. The flight is very characteristic, consisting of “odd jerks and vacillations, not unlike the motions of a butterfly.”
Fig. 203.—Sand Martins’ Nesting Holes.