When the young escape from the egg, they are either able to at once look after themselves more or less, at least to look for their food,—in which case they can see and are clothed with feathers at hatching (_precocious young_; _e.g._ fowls, ducks, gulls, and pewits),—or the young remain some time in the nest, as they are, to begin with, both blind and naked, and in this case they are fed for some time by the parents (_nestlings_; _e.g._ birds of prey, sparrows, nightingales, pigeons). In the frigid and temperate zones most species of birds do not remain in their native country after the breeding season; those which go south in the autumn are termed _migrants_; while birds which do not migrate, but remain in the district where they have bred, are known as _residents_ (sparrow, jay, magpie). _Gipsy migrants_ execute more or less extensive wanderings, influenced by want of food or other causes (woodpecker, titmouse, golden-crested wren, tree-creeper). The travels of such birds are not, like those of migrants, undertaken at a definite time of year, or in definite directions (N., S.), but many of their species collect together in large flocks for the purpose of wandering, like migrants. The following orders are usually distinguished: [Illustration: FIG. 30.—The Eagle Owl (_Otus maximus_). ] I. _Raptores_ (Birds of Prey), II. _Scansores_ (Climbers), III. _Passeres_ (Singing Birds), IV. _Gyrantes_ (Doves), V. _Rasores_ (Scratchers), VI. _Grallatores_ (Waders), VII. _Natatores_ (Swimmers), VIII. _Cursores_ (Running Birds). The Order Cursores includes the ostrich-like birds, and will not here receive further notice. ORDER: Raptores (BIRDS OF PREY). Upper beak hooked, covered with a skin (_cere_) at its base; four toes possessing strong claws, and provided with pads in their under side (Fig. 31); wings powerful. Birds of prey live in pairs, and breed once a year in nests composed of pieces of wood and branches. The young are nestlings (p. 51). Sight keen. These birds feed almost exclusively on vertebrates, principally mammals and birds. An idea of their food can be gained by examination of their “pellets”—roundish balls composed of the indigestible parts of their food, and disgorged from twelve to twenty hours after feeding. Two groups are distinguished—_diurnal_ and _nocturnal_ birds of prey. The first (Figs. 31, 32) have a laterally flattened head, eyes directed laterally, and tolerably stiff feathers. The nocturnal forms (“owls,” Figs. 30, 33) have a large head, flattened in front, with large eyes facing to the front, soft plumage, and hair-like feathers on the toes, of which two are directed forwards, one backwards, and one outwards. The radiating feathers round the eye constitute a “veil.” [Illustration: FIG. 31.—Head and Foot of Falcon. ]