Habitat selection and foraging success of wading birds in impounded wetlands in Florida

Most wading birds (Ciconiiformes) in Florida are tied to wetland habitats, and thus, to wetland protection and management. I investigated factors that influence piscivorous wading bird's foraging habitat selection and use at three spatial scales, and reasons why individuals choose to forage with others. Field work was conducted within the northern Indian River Lagoon, a sub-tropical estuary in east central Florida.; Based on follows from colonies, I found that nesting Great Egrets ( Ardea alba) and Snowy Egrets (Egretta thula) preferred estuarine wetland habitat and avoided freshwater wetlands. Interpretation of selection patterns depended on scale and habitats included. All birds followed foraged within 13 km of breeding colonies, well within the maxima reported for other colonies, suggesting that resources within impounded habitat met their energetic requirements.; To facilitate testing hypotheses regarding wading bird habitat selection, I measured wading bird prey density in paired vegetated and unvegetated sites within impounded salt marsh. Over 88% of the fish captured belonged to three species (Cyprinodon variegatus, Gambusia holbrooki, and Poecilia latipinna). Fish were highly clumped spatially, and density and biomass varied substantially between impoundments and seasons for both habitats.; Habitat selection within impoundments matched previous studies. Most species preferred unvegetated to vegetated habitat and all strongly preferred the area within 0.5 m of the boundary between types. Prey density had a strong effect on wading bird habitat use in unvegetated but not in vegetated wetland sites.; I measured the success rate of wading birds foraging alone and in mixed-species aggregations, and also measured the prey density at the foraging sites and nearby unused sites. Foraging sites had higher biomass (but not density) than the average level available throughout the landscape. Foraging groups occurred at the sites with higher prey density (but not biomass) than solitary foragers. Great Egrets benefited from foraging in groups, Snowy Egrets did not.; This study underscored the importance of edge habitat for foraging wading birds in impounded marshes, supported the social facilitation hypothesis regarding group foraging, and provided baseline data to measure responses from restoration and management of marsh habitats in Florida.