The marsh wren (Cistothorus palustris) is a small North American songbird of the wren family. It is sometimes called long-billed marsh wren to distinguish it from the sedge wren which is also known as short-billed marsh wren. Adults have brown upperparts with a light brown belly and flanks and a white throat and breast. The back is black with white stripes. They have a dark cap with a white line over the eyes and a short thin bill, and are 3.9 to 5.5 inches long. Marsh wrens are not very commonly spotted in the COSA, but have been spotted from September to May.