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
Summerland Peninsula Bird Area. It is home to one of the largest Little Penguin ("Eudyptula minor") breeding colonies in Australia, the second largest breeding colony of Australian Fur Seals ("Arctocephalus pusillus doriferus") in the world, one of the largest breeding colonies of Greater crested terns ("Sterna bergii") in Victoria and an important breeding ground for Short-tailed shearwaters ("Puffinus tenuirostris"). Several plants regarded as rare or threatened in either Victoria or Australia have been recorded on the peninsula, including River Swamp Wallaby-grass ("Amphibromus fluitans") listed as vulnerable in Australia. The peninsula was significantly modified by agricultural, residential and recreational developments until the 1980s