Gulls are not as contrastingly black and white and flap their wings more slowly and smoothly and lack the tube on top of the bill. Greater and Cory's Shearwaters are larger. Audubon's Shearwater has browner upperparts, dark undertail coverts and darker undersides of primaries. The very rare Little Shearwater is smaller with a whiter face and faster wingbeats. Formerly conspecific with the Black-vented Shearwater. The Black-vented Shearwater has dark undertail coverts.