Scarce and poorly known seabird breeding locally on islands of Azores, Madeira, and Canaries; very rarely seen at sea, usually as single birds, often not with other seabirds. Small, stiff-winged seabird that flies fast and low over the water (almost like an auk), gliding mainly in windy conditions. Note white-faced appearance, extensively white underparts contrasting with blackish upperparts. Trailing edge of upperwings often has a frosty sheen. Appreciably smaller and quicker on the wing than much commoner Manx Shearwater.