Gulls can be difficult to differentiate, specially since they come to Costa Rica in their non-breeding plumage. The definite marking for the Ring-billed Gull is the black tip of the beak for the Juvenile, and the Black ring on the middle of the beak for the adult. Note that the juvenile has pink bill and legs, whereas the adult has yellow bill and legs. The adult has a white belly and head, with gray wings and black wing tips. The juvenile is grayish, but has some streaking around the body. The individuals below were photographed in Vermilion Lakes, Alberta during a Photography Workshop with ToTheWonder, in September 2017.