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
Europa Island 100 pairs, probably of the subspecies "Puffinus lherminieri bailloni" previously considered endemic to the Mascarene Islands), dimorphic egrets and Caspian terns. The island is also home to an endemic subspecies of white-tailed tropicbird ("Phaethon lepturus europae"). There are three species of landbirds present, one of which is an endemic subspecies of the Malagasy white-eye ("Zosterops maderaspatanus voeltzkowi"). Additionally, the island is also home to its own species of hissing cockroach. Climate is affected by the Agulhas Current with water temperatures usually above 30 °C, southeast trade winds during the (austral) winter and occasional cyclones. While the island has probably been