Large, rather long-tailed, and relatively big-billed petrel of offshore subtropical and tropical waters in the eastern and central Pacific; not seen from mainland. Named for Juan Fernandez Islands in Chile, where the species breeds. Main identification features are relatively large size, gleaming white underparts with small black “comma” on bend of underwing, and dark cap blending into gray of hindneck. Upperparts show darker “M” pattern common to many petrels. Much larger than Masatierra Petrel and other small petrels.