Habitat
Freshwater and occasionally brackish marshes, mostly in cattails, reeds, and deep grasses (AOU 1983), also in or close to other emergent vegetation. Inhabits shallow, freshwater, emergent wetlands of every size and type, from roadside ditches and borders of lakes and streams to large cattail marshes (Brewer et al. 1991). Capable of using very small marshes (e.g., 5 nests have been found in a half-acre marsh) (see Brewer et al. 1991). Interspersion of open water and vegetation is an important habitat component (Brewer et al. 1991). Also occurs in salt marshes during the nonbreeding season (Cogswell 1977).
Nests in dense marsh vegetation over water, or in rank vegetation next to water; nest usually is less than 30 cm above water level. Often nests in vegetation next to open water. NON-BREEDING: In southern Canada overwinters in ice-free, spring-fed wetlands (Cannings et al. 1987).
Reproduction
Lays clutch of 5-12 eggs, April-June on the U.S. West Coast, May to June or July in the middle Atlantic and northern states. Incubation lasts about 19-20 days, by both sexes. Young leave nest soon after hatching, tended by both parents. Black downy chicks have been observed as late as August in Michigan (Brewer et al. 1991). Cornell Nest Record Program records indicate a nest success rate of 0.53 (Conway et al. 1994).