Cuckoos are generally medium-sized slender insectivores. Most are arboreal, but some, such as roadrunners and ground cuckoos, are terrestrial. The family has a cosmopolitan distribution, with the majority of species being tropical. Many species are migratory, and a notorious minority are brood parasites, laying their eggs in the nests of other species. Representatives are found on every continent except Antarctica, though the majority occur in tropical regions.