Great black-backed gull stomach contents of great black-backed gulls was made up of birds, while a further 17% of stomach contents was made up of tern eggs alone. Adult or fledged juveniles of various bird species have also been predaceously attacked. Some fully-fledged or adult birds observed to be hunted in flight or on the ground by great black-backed gulls have included "Anas" ducks, ruddy ducks ("Oxyura jamaicensis"), buffleheads ("Bucephala albeola"), Manx shearwaters ("Puffinus puffinus"), pied-billed grebes ("Podilymbus podiceps"), common moorhens ("Gallinula chloropus"), terns, Atlantic puffins ("Fratercula arctica"), coots ("Fulica" ssp.), glossy ibises ("Plegadis falcinellus"), rock pigeons ("Columba livia") and even predatory birds
Audubon's shearwater likely, as yet another synonym of "dichrous". The case of the more distinct "bannermani", the range of which is parapatric to that of the Pacific "dichrous", is more complicated. It has for some time been proposed as a distinct species, Bannerman's shearwater ("P. bannermani"). In the absence of more recent data to investigate this claim, its status continues to be altogether unresolved, though the case for it being at least a distinct subspecies in the "bailloni" clade seems good. Audubon's shearwater The Audubon's shearwater ("Puffinus lherminieri") is a common tropical seabird in the petrel family. Sometimes known as the dusky-backed