Everglades National Park (Fla)

Avian reproduction is generally resource dependent, and resource availability can vary through time and space. Wading birds breeding activity in southern Florida wetlands is limited by availability of aquatic prey, which is largely influenced by seasonal hydrodynamics. Restoration of natural hydrologic patterns is expected to increase populations and return breeding activity in the southern Everglades, but which prey support successful breeding at coastal colonies is unknown. To address this, I examined prey use of nesting White Ibis (Eudocimus albus) at coastal colonies in Everglades National Park (ENP) in a two-year observational study. I also examined ibis diets at nesting colonies located in three regions of the Everglades to better understand regional variation in trophic support of ibis reproduction. I found that crayfish and fish were used extensively in ENP in a year with exceptional ibis breeding activity, and I provide evidence that lengthened hydroperiods in higher elevation marl prairies may enhance crayfish production and availability in the southern Everglades. I found that crayfish were the most important prey type in all regions of the Everglades when reproductive effort was highest. These results add to the growing body of evidence that crayfish are important prey for ibis reproductive success in all parts of the Everglades, and suggest that increasing water flowing into the southern Everglades may incite greater nesting at historic colony locations. With this knowledge we can forecast how wading birds, and more generally wetlands of southern Florida, will respond to a changing environment and potential restoration scenarios.

The massive decline in mammal populations in Everglades National Park (ENP) has likely disrupted the fragile ecosystem unique to South Florida. Mammals populations in the park are a mere fraction of what they have been historically. However, very few studies have investigated some of the smaller mammals which are still widely present. Mark-recapture trapping was used over 4.5 years on tree islands in ENP to analyze the communities of three focal species: the hispid cotton rat (Sigmodon hispidus), marsh rice rat (Oryzomys palustris), and cotton mouse (Peromyscus gossypinus). We assessed the reproduction, effect of water levels and seasonality, and density of all three species over time. There was no significant association between water levels and reproductive activity for the cotton mouse or cotton rat, while the rice rat showed more reproductive adults during periods of standing water. The overall densities of all three species were higher in times of dry ground versus when the landscape was inundated. Average and maximum density estimates yielded higher numbers of rodents than observed in ENP.