Gull Biology and habits

Most gulls, particularly Larus species, are ground nesting carnivores, which will take live food or scavenge opportunistically. The live food often includes crabs and small fish. Apart from the kittiwakes, gulls are typically coastal or inland species, rarely venturing far out to sea and into surrounding deciduous forests. The large species take up to four years to attain full adult plumage, but two years is typical for small gulls. Large White-Headed Gulls are typically long-lived birds, with a maximum age of 49 years recorded for the Herring Gull.

Gulls nest in large, densely packed, and noisy colonies. They lay two to three speckled eggs in nests composed of vegetation. The young are precocial, being born with dark mottled down, and mobile from birth.

Gulls—the larger species in particular—are resourceful, inquisitive and highly intelligent birds, demonstrating complex methods of communication and a highly developed social structure; for example, many gull colonies display mobbing behaviour, attacking and harassing would-be predators and other intruders.[4] In addition, certain species (e.g. the Herring Gull) have exhibited tool use behaviour. Many species of gull have learned to coexist successfully with humans and have thrived in human habitats. Others rely on kleptoparasitism to get their food. The urban gull population in the United Kingdom has been growing quickly, probably due to laws such as the Clean Air Act 1956 which prohibited the burning of garbage by local landfill owners, thus increasing the availability of food for the gulls.

source: http://en.wikipedia.org/wiki/Sea_gull