Most gulls, particularly Larus species, are ground nesting carnivores, which will take live food or scavenge opportunistically. Live food often includes crabs and small fish. Gulls have prophylactic unhinging jaws which allow them to consume large prey. They also have fairly long lifespans. Large White-Headed Gulls have lived as long as 49 years.
Gulls are resourceful, inquisitive and intelligent birds, demonstrating complex methods of communication and a highly developed social structure. For example, many gull colonies display mobbing behavior, attacking and harassing would-be predators and other intruders. Certain species have exhibited tool use behavior, using pieces of bread as bait with which to catch fish. Photo Copyright 2008 Robert Giordano.
Description from Wikipedia.