My research is centered on deciphering the ecology, behavior, and movement of organisms, particularly marine turtles. I use stable isotopes in my studies, as they are biogeochemical markers that reflect trophic interactions and geographic origin. First, I will focus on individual vs. population level resource use patterns of sea turtles. I examined the long-term foraging history that can be obtained from sea turtle scute (the hard keratin covering on the shell) to investigate temporal consistency and specialization in resource use of both loggerheads (Caretta caretta) and green turtles (Chelonia mydas). I found that individual specialization is primarily due to foraging site fidelity and that foraging area preferences can contribute to differential reproductive output in loggerhead turtles. Second, I will discuss the use of stable isotopes as a tool in tracking animal migration. In the case of terrestrial organisms, hydrogen and oxygen stable isotope values in precipitation vary predictably with environmental and climatological factors. These markers reflect environmental water at the site where the tissue was synthesized and retain a record of origin when an animal moves. I have investigated how the incorporation of spatio-temporal variation in generating precipitation isoscape models can improve the ability to make accurate assignments of geographic origin. Whereas precipitation isoscapes have been used extensively in terrestrial studies, there are no equivalent isoscapes for the marine environment. Therefore, I developed and validated the use novel isoscapes for the Gulf of Mexico and Greater Caribbean and have provided the first application of probabilistic assignment to origin using marine isoscapes. I confirmed that the isoscape approach can be used to accurately decipher the movements of loggerheads in the Gulf of Mexico. I have also used long-term records in scute to examine sea turtle foraging behavior responses in the Gulf of Mexico following the Deepwater Horizon oil spill.