The Rusty-collared Seedeater lives in wet grasslands and marshes of southern South America. Males have a rusty collar.
Males have black-and-white markings and a rusty collar. Females do not share the male's full color pattern.
It uses flooded lowland grassland and shrubby marshes. It occurs in pairs or small flocks and eats mainly grass seeds, along with insects.
An extinction-risk assessment has not been added yet.