The ROCK DOVE (_Columba livia_)--see Coloured Plate XXVII.--is of a pale greyish hue on the mantle and bright blue on the under side; the head is light slate-blue, the throat deep slate-colour, glistening above with bright blueish green, and on its lower portion with a purple gloss; the rump is white. Two black lines pass across the deep grey wings; the tail-feathers are dark bright blue, tipped with black; those at the exterior are white on the outer web. The eye is sulphur-yellow, the beak black, with a light blue base, and the foot deep blueish red. The sexes are alike, and the young somewhat deeper in their colours than the adult birds. This species is thirteen inches long and twenty-three broad; the wing measures eight inches and one-sixth and the tail four inches and one-third. The Rock Dove in its natural state inhabits rocky sea-coasts, flying only sufficiently inland to procure food. It is spread over a very wide range of country, being met with as far north as the Faroe Islands, and as far southward as Africa. In Great Britain it is found both on the southern coasts of England and in the east and west of Scotland. In the Orkneys it breeds in the crevices of the rocks, the nests being at such a depth that they are quite out of reach. During the day the Doves associate in flocks and search for food, which consists principally of grain and seeds. The Rock Dove breeds twice in the season, each brood consisting of two young, generally a male and a female. The eggs are white and of a short oval shape, rather pointed at one end. From this species our Dove-cote Pigeons are derived, and they, like their original progenitors, seldom roost or settle on trees. The nest of the Rock Dove is a mere heap of straw, dry grass, and twigs, with a slight hollow in its centre for the reception of the eggs, which have a glossy, pure white shell. The female alone builds, but is supplied with materials by her devoted mate, who remains constantly near her both day and night. The blind and unusually helpless young are hatched about sixteen or eighteen days after the eggs are laid, and leave the shell within from twenty-four to thirty-six hours of each other. As with their congeners, the nestlings are at first nourished with pulp from the crops of their parents, then with partially digested seeds, and when fledged, with hard seeds, with the addition of tiny pebbles and bits of clay, to assist the still weak gizzard in the work of trituration. When about a month old the young are strong enough to quit the nest in company with their parents, who, however, soon leave them to their own devices, and at once commence their preparations for a second brood.