Cuckow, in ornithology, a genus belonging to the order of picae. The bill is somewhat cylindrical; the edges of the nostrils are a little prominent; the tongue is arrow-shaped, plain, and not divided; and the toes are of the climbing kind, i.e., two before and two behind. It is about the size of a pigeon. The cuckow is a migrating bird; it comes to Britain about the end of April, hatches its young, and disappears about St John's day. The cuckow neither builds a nest, nor sits upon its eggs; but takes possession of a nest built by small birds of the sparrow kind, in which it generally lays but one egg, which is hatched by the small bird along with its own eggs; during the time of hatching, the cuckow sits upon hedges or trees, and almost constantly sings. If the cuckow's egg be first hatched, she immediately throws out and destroys the eggs of the small bird; but if the small bird's eggs be first hatched, the cuckow allows the young to live till its own egg is hatched, and then destroys the young belonging to the small bird. The small bird feeds and brings up the young cuckow with as much care and attention as if it were its own, till it be able to procure its own food, when, some say, it ungratefully kills and eats its nurse. The cuckow feeds upon caterpillars and small birds; but is never transformed into a hawk, as is vulgarly supposed. It is a native of Europe. Linnaeus enumerates no less than 22 species, which inhabit different parts of the globe, and are chiefly distinguished by the shape of the tail and variations in colour.