This is the northern component of the two species of Marshbirds. In turn, the two marshbirds are relatively closely related to the Saffron-cowled Blackbird (Xanthopsar flavus). The Yellow-rumped Marshbird is a large, robust and pot-bellied icterid which is blackish brown and yellow. It is well named as this species has a yellow rumped, while its close relative is not. In addition, the Yellow-rumped is nearly blackish on the head and breast, and the flanks and thighs are yellow rather than brown. It takes a mix of marsh or tall moist grassland adjacent to drier more open areas. They nest in the tall dense grassland or marsh, and forage both in wetlands as well as grasslands. Yellow-rumped Marshbirds are usually found in small flocks, and nesting often occurs in small colonies. This marshbird is found from souther Brazil and E Paraguay south through northern Uruguay and Argentina in Misiones and Corrientes south to Entre Rios. In the southern part of the range it overlaps widely with the Brown-and-yellow Marshbird (P. virescens), but at any one site one species tends to predominate over the other. It appears that the Yellow-rumped Marshbird requires more shrubby habitats and avoids entirely treeless grassland and marsh.