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
Cape Byron Marine Park identifies the migratory little tern "(Sterna albifrons)" and the Beach stone-curlew "(Esacus neglectus)" as endangered. Seabirds that utilize the Cape Byron Marine Park are the providence pretal "(Pterodroma solandri)", flesh-footed shearwater "(Puffinus carneipes)", and the masked booby "(Sula dactylatra)" which are protected under the National Parks and Wildlife Act 1974. Although no invertebrates have been identified as endangered or vulnerable, it is important to acknowledge that there are a plethora of invertebrates within the Cape Byron Marine Park which are critical to the health of the local ecosystems. These include a variety of molluscs such as the gold ring cowries