The Brown-and-yellow Marshbird is distributed in north-east Argentina, Uruguay and south Brazil. It is found in open country such as grassland and marshes and has adapted to agricultural land. It prefers wet sites.
It is mainly olive-brown in colour with bright yellow on the lower breast and belly. There is a small, yellow epaulet which is just visible in the first photo but is very evident in flight. The bill is long, thin and black.