This work integrates movement studies of herring gulls (Larus argentatus) and great black-backed gulls (Larus marinus) with stable isotope and microbial analyses to assess how urbanization influences the foraging ecology and microbiome of gulls on both an individual and colony level. We are examining spatial and trophic ecology of gulls using small, lightweight GPS tags at three study sites at differing distances from a major urban centre: Jamaica Bay in New York City (our most urban site), Stony Brook Harbor on Long Island, New York (our intermediate site), and Tuckernuck Island off of Nantucket, Massachusetts (our least urban site). Collecting blood samples and microbial swabs from tracked gulls and pairing these datasets with analyses of foraging behavior allows us to  to investigate how factors such as diet and microbiome differ between gulls from the different study sites and between gulls using different foraging locations and food sources.