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
Gwennap Head 15 October each year and most of the recording was by volunteers who spent up to twelve hours a day on seawatch. The main targeted species were Balearic shearwater ("Puffinus mauretanicus") and basking shark, along with the ocean sunfish (or common mola). Marine mammals such as whales, dolphins and grey seal ("Halichoerus grypus") were additional main targets. During a seawatch on 28 August 2015 a red-billed tropicbird ("Phaethon aethereus") was seen over the Runnel Stone, a bird that usually frequents tropical areas. Gwennap Head is part of the Land’s End granite massif with shallow, free-draining and acidic soils. The dominant