Gulls (often informally called seagulls) are birds in the family Laridae. They are most closely related to the terns (family Sternidae) and only distantly related to auks, skimmers, and more distantly to the waders. Until recently[vague], most gulls were placed in the genus Larus, but this arrangement is now known to be polyphyletic, leading to the resurrection of several genera.
Gulls are typically medium to large birds, usually grey or white, often with black markings on the head or wings. They typically have harsh wailing or squawking calls, stout, longish bills, and webbed feet. Gull species range in size from the Little Gull, at 120 g and 29 cm, to the Great Black-backed Gull, at 1.75 kg and 76 cm.
Gulls nest in large, densely packed 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 upon hatching.
Source: en.wikipedia.org/wiki/Sea-gull - 23.03.2010
Life in the Air
Birds are build so genial that they can fly: light bones, wings und feathers - and some more things - exactly balanced - that works together, that the birds can move safely and efficiently in the air.