The marsh wren, Cistothorus palustris, breeds throughout the United States, as well as in southern Canada and northern Mexico. It winters along coastal areas of North America, in parts of the western and southern United States, and in Mexico. The marsh wren is a year-round resident of Utah, although some individuals that breed in Utah migrate to warmer areas for winter. As its name implies, this species prefers marshy habitats.
Nests are built in wetland vegetation; the male begins several nests, one of which is finished by the female. The female lays a clutch of three to ten eggs, and then incubates the eggs for about two weeks. The young leave the nest at about two weeks of age. Marsh wrens may raise two or three broods each year. Interestingly, adults may destroy the eggs and young of other birds that nest in the vicinity of their nest.
The marsh wren is active during the day. Its diet is composed primarily of insects.