Medium-sized, dark brown shearwater with silvery flashes on underwings. Narrow wings with quick, deep wingbeats. Widespread and common, especially in Pacific. Can be in massive flocks. Seen from shore more frequently than other shearwaters, especially off the west coast of the U.S. Extremely similar to Short-tailed Shearwater, but Sooty is heavier and has straighter wings; also look for slightly longer bill and less rounded head. Brown plumage reminiscent of Flesh-footed Shearwater but narrower-winged and Sooty has smaller, all-dark bill.