The Argentine biodiversity record lists the Brown-and-yellow Marshbird as native in Argentina. A university field account describes its brown-and-yellow plumage and ground foraging.
The field account describes olive-brown head, back, throat, upper chest, flanks, and undertail area, with yellow on the lower chest, belly, shoulders, and inner wing coverts.
The account reports pairs or groups, sometimes reaching roughly 25–30 birds. On the ground, it searches beneath objects for food.
An extinction-risk assessment has not been added yet.