The Blue-and-yellow Tanager (Thraupis bonariensis) is found in Argentina, Uruguay, Brazil, Paraguay, Bolivia, extreme northern border Chile, and Andean Peru and Ecuador.
Some southern region birds migrate northeastwards in the austral winter into eastern Bolivia and northeastern Argentina; also Paraguay where the birds are only migratory non-breeding residents.
They inhabit subtropical or tropical dry forests, moist lowland forests and montanes, high-altitude shrubland, and heavily degraded former forest.
Males of the eastern nominate group have a black back, while the members of the western darwinii group have a green back.
Females and juveniles have a plain brownish plumage.