Very small black-and-white shearwater of warm tropical waters. Can be seen from shore off the coast of Oaxaca. Often in flocks, sometimes of thousands, resting on the water and in feeding flocks with Brown Boobies, Black Terns, and other shearwaters. Flight quick and low, with hurried wingbeats and only short glides. Smaller and shorter-winged than Black-vented Shearwater and rare Townsend’s Shearwater. Black-vented has messier brown colors on the side of its head, without distinct dark cap of Galapagos. Townsend’s is blacker above with white patches (saddlebags) at sides of rump.