Cuckoos are birds in the Cuculidae family, the sole taxon in the order Cuculiformes. The cuckoo family includes the common or European cuckoo, roadrunners, koels, malkohas, couas, coucals and anis. The coucals and anis are sometimes separated as distinct families, the Centropodidae and Crotophagidae respectively. The cuckoo order Cuculiformes is one of three that make up the Otidimorphae, the other two being the turacos and the bustards.
The cuckoos are generally medium-sized slender birds. Most species live in trees, though a sizeable minority are ground-dwelling. The family has a cosmopolitan distribution; the majority of species are tropical. Some species are migratory. The cuckoos feed on insects, insect larvae and a variety of other animals, as well as fruit. Some species are brood parasites, laying their eggs in the nests of other species and giving rise to the metaphor cuckoo's egg, but the majority of species raise their own young.
Cuckoos have played a role in human culture for thousands of years, appearing in Greek mythology as sacred to the goddess Hera. In Europe, the cuckoo is associated with spring, and with cuckoldry, for example in Shakespeare's Love's Labour's Lost. In India, cuckoos are sacred to Kamadeva, the god of desire and longing, whereas in Japan, the cuckoo symbolises unrequited love.
The cuckoos have a cosmopolitan distribution, ranging across all the world's continents except Antarctica. They are absent from the south west of South America, the far north and north west of North America, and the driest areas of the Middle East and North Africa (although they occur there as passage migrants). They generally only occur as vagrants in the oceanic islands of the Atlantic and Indian Oceans, but one species breeds on a number of Pacific islands and another is a winter migrant across much of the Pacific.
Cuculinae is the most widespread subfamily of cuckoos, and is distributed across Europe, Asia, Africa, Australia and Oceania. Amongst the Phaenicophaeinae cuckoos the malkohas and Asian ground-cuckoos are restricted to southern Asia, the couas are endemic to Madagascar and the yellowbill widespread across Africa. The coucals are distributed from Africa through tropical Asia down into Australia and the Solomon Islands. The remaining three subfamilies have a New World distribution, all three are found in both North and South America. The Coccyzinae reaches the furthest north of the three subfamilies, breeding in Canada, whereas the anis reach as far north as Florida and the typical ground-cuckoos the south west United States.
For the cuckoos suitable habitat provides a source of food (principally insects and especially caterpillars) and a place to breed, for brood parasites the need is for suitable habitat for the host species. Cuckoos occur in a wide variety of habitats. The majority of species occur in forests and woodland, principally in the evergreen rainforests of the tropics. Some species inhabit or are even restricted to mangrove forests; these include the little bronze cuckoo of Australia, some malkohas, coucals, and the aptly-named mangrove cuckoo of the New World. In addition to forests some species of cuckoo occupy more open environments; this can include even arid areas like deserts in the case of the greater roadrunner or the pallid cuckoo. Temperate migratory species like the common cuckoo inhabit a wide range of habitats in order to make maximum use of the potential brood hosts, from reed beds (where they parasitise reed warblers) to treeless moors (where they parasitise meadow pipits).