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
Giannutri in the northern part which become "garrigue" in the southern. Plants as "arbutus", "Myrtus", "pistacia lentiscus", mock privet, Mediterranean buckthorn, "juniperus phoenicea" and "limonium sommierianum" knew only on Isola del Giglio and Montecristo, grow up on the island. The mild climate has favoured the growth of plants such as "euphorbia", palm trees and wild orchids. The marine flora is abundant in sponges, madreporaria, black coral and red coral. The island, as all that of the Tuscan Archipelago, is a place where the bird migration take a stop along their seasonal movement from North to South. The Audouin's gull, Puffinus yelkouan,