Adults have streaked rusty, buff and black upperparts with an unstreaked gray breast, light belly and a white throat. The wings are strikingly rusty. Most males and a few females have a rust-colored caps. Their face is gray with a dark line through the eye. They have a short bill and fairly long legs. Immature birds and winter adults usually have two brown crown stripes and much of the gray is replaced with buff.
This site contains all information about Swamp Sparrow.