Distribution in the Americas
The Common Diuca-Finch can be found in the countries of Chile, Argentina, Bolivia, Brazil, and Uruguay. More specifically, regular non-breeding populations are found in Argentina, southeast Brazil, and eastern Uruguay, while year-round populations are found in southern Bolivia, Argentina, and Chile (Parker et al. 1996, Jaramillo 2011). This species occurs in the following Zoogeographic Regions: Subtropical Pacific, Southern Andes, Central South America, and Patagonia (Parker et al. 1996). The center of elevational abundance is in the lower subtropical zone, found from the lowlands to a maximum elevation of 2000 m (Parker et al. 1996). Diuca diuca is generally a resident species, but the migratory populations (D. d. minor, Bonaparte 1850) travel northward from Patagonia into Pampas in the austral winter (Bullock 1940, Parker et al. 1996, Jaramillo 2011).
Distribution outside the Americas
The Common Diuca-Finch is endemic to South America.
Parker et al. (1996) list the primary habitat as arid lowland scrub. Additional habitats used by this species include the following, in decreasing order of importance: arid montane scrub and second-growth scrub (Parker et al. 1996). More specifically within these habitats, these birds can be found in shrubs, cultivated gardens and farmland, matorral shrub lands, forest edges, and desert scrub (Ridgely and Tudor 1989, Jaramillo 2003, Perlo 2009, Ridgely and Tudor 2009). Their presence on farmland is possibly a strategy to avoid nest predation that is common in more dense vegetation (Pescador and Peris 2014).
This species is perhaps not as common in parts of its range in south-central Chile as it once was, with perhaps more intensive agriculture and expanding populations of House Sparrows (Passer domesticus) causing a decline in Diuca diuca populations since 1990 (Jaramillo 2011).