Does a long-term shift in Wood Stork diet foreshadow adaptability to human-induced rapid environmental change?

Geographically isolated wetlands (GIWs) have been increasingly recognized for their importance in providing ecosystem services, including support of regional biodiversity. These wetlands serve as valuable foraging and breeding habitat for wetland-dependent species, including wading birds. In certain regions of the U.S. Southeastern Coastal Plain approximately two-thirds of GIWs are impacted by adjacent human land use. We quantified wading bird density in agricultural and natural GIWs to determine the factors influencing their use of these habitats. Using monthly transect surveys, we found that wetland specific variables, including prey abundance and size, wetland surface area, and dry-down rate, were better predictors of wading bird density than landscape level variables such as wetland density and distance to breeding colony. Bird density was highest in agricultural wetlands early in the hydroperiod, but as GIWs dried down, density dropped in agricultural wetlands and rose in natural wetlands. Collectively, these results suggest that wading birds in the Coastal Plain rely on a matrix of both agricultural and natural wetlands, and their use of wetlands varies temporally, peaking in late spring, to maximize prey availability. The seasonal process of receding water levels in GIWs and subsequent concentration of aquatic fauna provides important food resources for nesting wading birds.