[3] In January 2021, both the South American Classification Committee (SACC) of the American Ornithological Society (AOS) and the International Ornithological Congress (IOC) elevated the former subspecies A. f. dorbignii to species status as the moss-backed sparrow.

Its underside is white with grayish edges and a narrow black band across the upper chest.

The "gray-backed" subspecies is found further south, in central and southern Brazil, eastern Bolivia, much of Paraguay, and northeastern Argentina.

[2][3] The saffron-billed sparrow primarily inhabits tropical deciduous forest, both primary and second-growth.

[3] The song of the saffron-billed sparrow is a series of rapid notes variously described as "tsit, tsee-tsi-tsi, tseép-seép-tseép" and "sidsidlidsidlsidli".