In Florida, roughly 18,000 ha of treatment wetlands called Stormwater Treatment Areas (STAs) have been constructed on agricultural land to reduce phosphorous loads to the Everglades. Little is known about how avian communities in these STAs compare to those present on other similar land types. In 2008–2009, point counts were conducted seasonally in the STAs, nearby croplands, and natural Everglades marsh to compare avian communities among these habitats. Overall, avian densities were nearly three times greater in STAs than in the croplands and 38 times greater than in the natural marsh. Local species richness in the STAs was 78% greater than in croplands and nearly four times greater than in the natural marsh. Although natural marshes may have more structural complexity than the croplands and STAs, their oligotrophic status probably limits their ability to support a large bird community. Avian densities varied seasonally among habitat types; avian density was greatest in the winter in STAs as a result of high densities of migratory waterfowl. The STAs may be providing wintering habitat to a significant portion of the North American waterfowl population, including as much as 8% of the breeding population of American Coots (Fulica americana). If the trend of increasing numbers of treatment wetlands continues, it has the potential to alter the distribution of wetland birds, a group that has previously suffered population declines because of habitat loss.