In spring, when the birds have paired, they set themselves to work at once to collect the necessary materials for their nest. Each carries its blade of grass or stem of moss. Large birds content themselves with a coarser structure--chips of wood, or branches of trees interlaced with twigs, lined with hair and other soft materials, are fashioned into the necessary shape. But the smaller species really display great art in framing their miniature dwelling, which they furnish inside with wool, blades of grass, or down, the male and female labouring in the common work. Their effort is to make a soft, warm, and solid bed on which to deposit the coming eggs. The mother-bird has recourse to all sorts of cunning devices in order to conceal her nest from prying eyes, choosing for this purpose the heart of a leafy bush, the forked limb, the concealed crack or hollow in the trunk of a tree, the chimneys of a house, crevices in a wall or under a roof. Curiously enough, the nests of the same species are always fashioned in precisely the same manner. The Kinglet, or Wren (Fig. 72), builds its nest under a bank, generally near some brook; it is neatly formed of moss, nearly covered with leaves, and lined with small feathers, hair, and wool. In this nest the smallest of our native birds lays six delicate little white eggs, marked with small pink spots. The Humming-birds (Fig. 73), which flit about in tropical woods, build their nests of grass, lined with feathers. The House Sparrow (Fig. 74) builds its nest under the eave of some house; while the Hedge Sparrow (Fig. 74) chooses the fork of a hawthorn-tree in which to construct its children's home. The Magpie, more ambitious, constructs, in the topmost fork of some tall ash, or poplar, or elm, its nest of branches interlaced with twigs, and lined with fine grass, hair, and other soft materials (Fig. 75). It is a large and consequently a conspicuous fabric, elliptical in form, composed first of rough boughs, on which is laid a quantity of mud, and then a layer of twigs, the whole lined with fibrous roots and other soft material. The Goldfinch builds its nest on trees; it is composed of grass, moss, and lichens, and lined with the down of various plants and such other soft material as comes in its way, elaborately interwoven with wool and hair (Fig. 76). [Illustration: Fig. 76.] [Illustration: Fig. 77.] The Owl, _Strix flammea_, chooses her nest in some obscure nook of an old tower, the steeple of a church, a dovecot, or the hollow of an aged tree (Fig. 77). It is composed of twigs and straws loosely arranged.