The migratory behavior of North Atlantic leatherback turtles (Dermochelys coriacea) has been documented in the Wider Caribbean, but the migratory movements of leatherbacks nesting in South Florida are relatively understudied. Our knowledge of their migrations is currently limited to ten nesting females tracked from the east coast of Florida that either moved north to the Northern Atlantic or east to the coast of Western Africa. These results bring to light the need for further investigation and larger sample sizes to identify and determine the relative importance of the different foraging areas for the leatherbacks nesting in South Florida. Here, I analyzed stable carbon (δ13C) and stable nitrogen (δ15N) values in whole blood and skin of leatherbacks nesting in South Florida between 2014 and 2017 to estimate the putative foraging origins of these nesters prior to coming to South Florida to nest. This study provides some of the first stable isotope inferences and insights into the variable pre-nesting foraging habitat locations of Florida’s leatherback population. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

The hydrological and topographical variation of wetlands can affect the behavior, population growth, and local densities of aquatic species, which in turn can drive the behavior and density dynamics of gleaning predators. Prey availability, primarily determined by prey density and water depth in wetlands, is an important limiting factor for nesting wading bird populations, top predators in the south Florida Everglades. The Everglades is able to support large colonies of nesting wading birds because of the microtopographic variation in the landscape. Some types of prey concentrate in flat, shallow sloughs or become trapped in isolated pools as they move down from higher elevation ridges with receding water levels. Manipulations to the hydrology and landscape of the Everglades has negatively impacted nesting wading bird populations in the past, and may continue to be detrimental by allowing flat, shallow sloughs to be intersected by deep canals, a potential refuge for wading bird prey. In addition, the subtle elevation differences between the ridge and slough landscape may be an important mechanism for increasing slough crayfish (Procambarus fallax) prey availability for the most abundant and seemingly depth-sensitive Everglades wading bird, the White Ibis (Eudocimus albus). I implemented a 2-year experimental study in four replicated manmade wetlands with controlled water recession rates in order to determine the effects of proximate deep water (akin to canals) on fish prey concentrations in the sloughs, as water levels receded similarly to a natural Everglades dry season. I also calculated average daily wading bird densities with game cameras (Reconyx PC800 Hyperfire) using timelapse imagery over 60 days to determine when and where wading birds responded to changing prey concentrations. I completed an additional observational study on White Ibis and slough crayfish prey from the first year of data (2017). Crayfish make up the majority of the diet for nesting White Ibis, and literature has suggested crayfish are most abundant at slough depths much deeper than previously proposed foraging depth limitations for White Ibis. This study specifically compared recent determinations about crayfish movement dynamics in the ridge and slough system with White Ibis foraging behavior and depth limits. Results from the first experimental study suggest that canals might be an attractive refuge for relatively large prey fishes (> 3 cm SL) in sloughs, but it is uncertain if the fencing blocked all prey fish movement. The second observational study determined White Ibis foraging activity was primarily driven by a down-gradient crayfish flux from ridge to slough, with the majority of foraging activity occurring at much deeper slough depths than previously suggested water depth limitations for White Ibis. Results from both of these studies support the importance of preserving the ridgeslough landscape of the Everglades to sustain high prey availability for wading birds. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection