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
Heinroth's shearwater behaviour of close relatives). There is very little information about the species and it is uncertain if it is threatened or in decline. BirdLife International (2006) Species factsheet: Puffinus heinrothi. Downloaded from http://www.birdlife.org on 26/7/2006 Heinroth's shearwater Heinroth's shearwater ("Puffinus heinrothi") is a poorly known seabird in the family Procellariidae. Probably a close relative of the little shearwater or Audubon's shearwater (with which it is sometimes considered conspecific), it is distinguished by a long and slender bill and a brown-washed underside. This species is restricted to the seas around the Bismarck Archipelago and northern Solomon Islands. The breeding sites of