Wading bird use of geographically isolated wetlands in the southeastern U.S. coastal plain

Geographically isolated wetlands (GIWs) are a prominent feature of the U.S. southeastern Coastal Plain. These wetlands support species rich plant and animal communities, particularly within the longleaf pine ecosystem. Currently, more than 50% of GIWs in the Southeast have been impacted by human land uses. Modification of wetlands influences species such as wading birds, which serve as important apex predators. Due to their high trophic status, wading birds are significant indicators of ecological health and productivity in wetland ecosystems, yet no studies exist that quantify their presence in coastal plain GIWs and identify drivers influencing their use of these systems. I conducted weekly systematic surveys for wading birds and monthly surveys of potential prey items at 15 GIWs including reference (cypress swamps and herbaceous marshes) and agriculturally-modified GIWs across the hydroperiod of February through July. An information theoretic modelling approach was used to identify wetland features, hydrologic characteristics, and landscape components that explained patterns of wading bird density. Density, measured in birds per hectare, was highest in agriculturally-modified wetlands from February to May (M=3.56, SD=6.58) and highest in reference wetlands in June and July (M=7.51, SD=7.93). Prey abundance (catch-per-unit effort) for all wetland types increased early in the season (February-March) and was relatively stable for the remainder. Top explanatory variables were month and the interaction of wetland type with prey abundance. A better understanding of wading bird use of human-modified wetlands can provide tools for more informed conservation decisions for these birds and the wetland systems they rely on.