Audubon's shearwater ill-resolved clade also including such species as the little shearwater, the Manx shearwater ("P. puffinus") or the black-vented shearwater ("P. opisthomelas"). The little-known Heinroth's shearwater ("P. heinrothi") is sometimes considered a subspecies of either Audubon's or the little shearwater. Though it is likely to be another member of that close-knit group, its actual relationships remain uncertain due to lack of specimens. Audubon's shearwater itself has around 10 subspecies. Several have at one time or another been suggested to constitute separate species. For example, the Galápagos Islands population has turned out to be a very distinct species, the Galápagos shearwater ("P.
Bannerman's shearwater Bannerman's shearwater Bannerman's shearwater ("Puffinus bannermani") is a seabird in the Procellariidae family formerly considered conspecific with Audubon's shearwater ("Puffinus lherminieri"). Little is known of this species other than that it breeds in the Volcano Islands in the Ogasawara Group to the southwest of Japan and doesn't seem to range far from this area. The species population size has not been estimated but is assessed to be decreasing. Not much is known about this species and more research is required to obtain an understanding of its ecology. Based on the ecology of closely related species, "P. bannermani" is thought likely