Seagulls feed on small marine animals such as fish, crustaceans (crabs, shrimps, etc.), starfish, and mollusks (mussels, clams, oysters). But they can also feed on plants, insects, worms, earthworms, slugs, snails, small birds (which they attack in flight), bird eggs (others species but also theirs), rats and mice, chicks or small ducks, food scraps, and …