Among the effects of global warming will be sea level rise (SLR) that will bring about coastline transformation and impacts on low-lying coastal dry forest. This study has been conducted in the Jobos Bay National Estuarine Research Reserve (JBNERR) on the eastern south coast of Puerto Rico. We conducted extensive mist netting at seven sites in the reserve and documented the occurrence and movements of several species of migratory Warblers in the Reserve. We also obtained information on the possible origins of long distance migrants that visit the Reserve in winter. Stable isotope methods involving the use of the measurement of stable hydrogen isotope abundance in feathers (δ2Hf) of Neotropical migrant songbirds that breed in North America and molt prior to fall migration can be used to connect the breeding and wintering grounds of individual birds (migratory connectivity). The feather deuterium isoscape (δ2Hf) for North America is much better known and structured than those for the Neotropics. Therefore, it makes more sense to sample birds at known wintering locations rather than at known breeding locations. Herein we demonstrate how feathers sampled on the wintering grounds at Jobos Bay, Puerto Rico can be used to infer breeding origins in North America. Using Bananaquits (Coereba flaveola) as our local baseline, our preliminary results indicate that some over-wintering Jobos Bay Northern Waterthrushes (Parkesia noveboracensis) and Yellow Warblers (Setophaga petechia), originate from breeding grounds at latitudes as far north as mid- to upper Hudson’s Bay, Canada (Zones D, E, and F) and that some first-year Yellow Warblers, Prairie Warblers (Setophaga discolor) and Ovenbirds (Seiurus aurocapilla) may experience eccentric molts en route to Puerto Rico. Our results also suggest the occurrence of two races of Prairie Warblers at Jobos Bay. Continuing and future studies involving additional feather sampling and the deployment of light-level geolocators will help pinpoint more specific breeding assignments and refine conservation efforts for these species. In addition, this Blake-Nuttall funded project has provided the basis for the development of a new academic ornithology program at Universidad del Turabo, the only such university program in Puerto Rico.