family name Formicariidae, any of numerous birds of the American tropics (order Passeriformes). There are about 230 species in more than 50 genera. Like their near relatives the Furnariidae, antbirds are highly diverse; all are of small to medium size (9.5 to 37 centimetres [4 to 14 inches]), with drab, fluffy plumage (sexes usually unlike); short, rounded wings; variable but often rather stout bill with a hooked (sometimes also notched) tip; strong legs; and front toes partly joined at the base. Most make cup-shaped nests. All have loud, usually unmusical voices that may be heard in echo duets. Antbirds are insectivorous, and many species habitually follow columns of marching ants. Beyond these few generalizations, subgroups are vaguely characterized by popular names likening them to birds of other families-antwren, antpitta, antshrike, ant-vireo, ant thrush (the former name of the group); still other antbirds are called bare eyes, fire eyes, and bush bird.