The ‘Larus delawarensis’ is the most common and widespread gull in North America, especially inland, and numbers are probably still increasing. These gulls are sociable in all seasons; concentrations at nesting colonies or at winter feeding sites may run into the tens of thousands. The Ring-bill has adapted thoroughly to civilization. Flocks are often seen resting in parking lots, scavenging for scraps around fast-food restaurants, or swarming over landfills.
Resource: https://www.audubon.org/field-guide/bird/ring-billed-gull
Under The White Oak Leaves 