Smaller Black-vented Shearwater has plain upperwings. Larger Pink-footed Shearwater has darker underparts and plainer upperwings. Mottled Petrel is smaller with a dark belly and a different underwing pattern. 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.