The cuckoos belong to the family, Cuculidae, of close to passerine birds. With cuckoos, the turocos are also added to the order Cuculiformes. Unique Hoatzin is also included in Cuculiformes by zoologists and taxonomists. The cuckoo family also includes roadrunners, malkohas, couas and anis. Coucals and anis are referred as distinct families sometimes. The cuckoos are slim medium sized birds. The family has the distribution of type cosmopolitan, where many species being tropical. The species which are sensitive to temperature are migratory. Mostly the cuckoos are insectivorous, and it also intake caterpillars, fruits. Many cuckoos are brood parasites, where it lays the eggs in other species nets.