Oystercatchers are large, 18 to 20-inch shorebirds, about the size of a crow. They have a long, orange bill which is chisel-tipped at the end. They mostly eat oysters (as you might expect), clams, mussels, and marine worms. When feeding, their knife-like bill is used in two different ways. If they find an oyster with its shell partly open, they quickly slide the bill in and cut the muscles of the oyster. Then they can pry it open and eat the oyster. At other times, they just use the bill to hammer on the oyster shell until it breaks.