A medium-sized bird belonging to the Cuculidae, a family of 143 species that also includes the roadrunners, coucals, anis, and others. They occur worldwide except for Antarctica but mainly in the tropics, in forests, grasslands, and marshes; some species are migratory. Most are insectivores. The Old World subfamily Cuculinae comprises about 55 species of woodland birds that are brood parasites, each female laying a single egg in the nest of its host species. The common cuckoo (Cuculus canorus) winters in Africa and migrates in summer to Europe and Asia.