The marsh seedeater (Sporophila palustris) is a species of bird in the family Thraupidae.

It is threatened by habitat loss, trapping for the pet trade, and pesticides.

A rare seedeater very similar to this species breeds in the Entre Ríos province of Argentina,[2] and a few individuals have been found in Corrientes province and in southern Brazil, eastern Paraguay, and southeastern Uruguay.

Differences are that it has a wide white collar all the way around the neck; the back is chestnut, not grey; and the rufous of the belly is darker than the marsh seedeater's.

Accordingly, the American Ornithologists' Union's South American Classification Committee voted in 2008 to remove S. zelichi from their list, with two voters favoring the suggestion that it is a morph of the marsh seedeater.