Cuculiformes

The Cuculiformes are an order of birds that includes cuckoos, anis, and coucals, with many members placed in the family Cuculidae. They are typically medium-sized birds with slender bodies, long tails, and strong legs. Adults often display cryptic brown, gray, or greenish plumage; their bills are relatively thin and gently down-curved, and many species have zygodactyl feet (two toes forward and two backward). They occupy a wide range of habitats, from dense forests and woodlands to savannas, wetlands, and agricultural areas, and they occur across most continents except extreme polar regions.

Behaviour and ecology: Diet is mainly insects and other invertebrates, supplemented by fruit and small vertebrates in some species. A defining feature of many cuculiforms is brood parasitism, especially among the genus Cuculus (e.g., the common cuckoo), where females lay eggs in the nests of other bird species and leave the care of the young to hosts. Parasitism varies by lineage; not all species are parasitic, and several genera (such as coucals) raise their own young. Vocalizations are often distinctive, with calls ranging from whistles and coos to harsh cackles; some species are highly migratory, while others are resident.

Taxonomy and distribution: The order is distributed globally, with greatest diversity in tropical regions. In modern classifications, Cuculiformes encompasses the cuckoos and their relatives, and ongoing molecular studies continue to refine relationships among the lineages within the group.