Retiring, rather bland sparrow of humid tropical lowlands. Favors forest understory and adjacent thickets and tangles. Very similar to Olive Sparrow, which occurs in the same areas but prefers brushy fields rather than forest understory. Green-backed has brighter greenish upperparts and a cleaner gray head with well-defined black stripes, but best told by song. Songs of both species are variable, but Green-backed song typically rather even-paced, unlike accelerating notes of Olive Sparrow. Calls of both species similar.