The Louisiana and Texas populations also breed in salt marshes. They reach sexual maturity in their second year. Nest building and egg laying begins within weeks of the birds' arrival on their breeding grounds. Many pairs may utilize the same habitat, sometimes forming large colonies with little evidence of intraspecies aggression. Courting birds vocalize to each other and engage in mutual preening and bill rubbing.
Copulation occurs at or near the nest site.
Both parents participate in building the cup shaped nest of small twigs lined with finer material. The nest is usually placed on top of emergent aquatic vegetation or in a low shrub or tree over the water. Locating the nests in or over water helps protect the eggs and nestlings from mammalian predators such as skunks, racoons, and long-tailed weasels. Nests are also preyed on by gulls, magpies, ravens, crows, owls, and grackles. Three to four pale bluish-green eggs are laid.