Extremely similar and much more common Sooty Shearwater has a less rounded head with a more gradual slope to the forehead. Sometimes Sooty Shearwaters have paler wing linings and appear slightly larger. Flesh-footed Shearwater has a pale bill and feet. Dark Norther Fulmars are much stockier with yellow bills. Immature gulls are superficially similar but can be separated at great distances by their different flight styles. Shearwaters fly closer to the surface of the water, often disappearing behind swells, alternating flaps with long glides on downcurved wings.