The Rufous-breasted Antthrush is similar to other members of the genus Formicarius in being a chunky, short-tailed, forest-floor dwelling bird that characteristically walks like a chicken. Its distribution is complicated, but is generally found in the upper foothills along the Caribbean slope of Costa Rica and western Panama, as well as along both slopes of the Andes in Colombia and Ecuador, and the Amazonian slope foothills through much of Peru. It is local in the Andes of southwestern Venezuela. Generally found at higher elevation than either Black-faced Antthrush (Formicarius analis) or Black-headed Antthrush (Formicarius nigricapillus), and differs greatly from those species by primary vocalizations. Song is a loud, ringing two-note whistle “tuu-tuu.” Usually seen singly or in pairs throughout the forest, but occasionally attends army ant swarms. Plumage differs from other Formicarius species by having entirely rufous underparts, which can be difficult to see in dark forest situations.