All crescentchests are sharp looking species, and they now are considered to comprise a family separate from other suboscine passerines. This distinctiveness is clear based on their striking plumage, as well as their vocalizations. The Olive-crowned is the southernmost of the crescentchests, and like its relatives it is found in dry forest edge and shrub-slopes in Bolivia, Argentina and Paraguay. The voice varies geographically, there is a fast singing population and a slow singing population, it is likely that the two are better treated as separate species. This crescentchest is olive above, with a distinct pale supercilium and a black mask. Below it shows a buffy throat, a black crescent on the chest and rufous underparts.