Wading Bird Use of Wastewater Treatment Wetlands in Central Florida, USA


We documented the use of two wastewater treatment wetlands (secondarily treated urban sewage) in central Florida by wintering and breeding long-legged wading birds (Ciconiiformes), and compared densities of birds at these sites to a large, naturally fluctuating wetland nearby. Winter densities at all three sites in central Florida were much higher than at other natural wetlands in southern Florida and Nicaragua. White and Glossy Ibises (Eudocimus albus and Plegadis falcinellus) were much more common at the natural site in central Florida than at the wastewater sites, presumably because water depths at the latter sites were too deep for foraging. Densities of ardeids were not notably different among the sites. Breeding colonies of Wood Storks (Mycteria americana), Cattle Egrets (Bubulcus ibis) and Great Egrets (Casmerodius albus) formed at both wastewater sites during the study, probably because water conditions were stable. Great and Snowy Egrets (Egretta thula) that we followed from these colonies often foraged in the wastewater impoundments, but Wood Storks and White Ibises followed from wastewater and nearby colonies rarely did. These wastewater impoundments appeared to offer attractive feeding conditions to ardeids, but not to ibises or storks, and appear to have high value as colony sites. We outline a number of potential health risks for wading birds using these wetlands.

Colonial Waterbirds