The white-bellied storm petrel (Fregetta grallaria) is a species of seabird in the family Oceanitidae. It is found in Angola, Argentina, Australia, Brazil, Chile, Ecuador, French Polynesia, French Southern Territories, Maldives, Namibia, New Zealand, Perú, Saint Helena, and South Africa. Its natural habitat is open seas. Taxonomy The white-bellied storm petrel was formally described in 1818 by the French ornithologist Louis Jean Pierre Vieillot. He used the French name "Le pétrel échasse" and coined the binomial name Procellaria grallaria. The white-bellied storm petrel is now placed in the genus Fregetta that was introduced in 1855 by the French naturalist Charles Lucien Bonaparte. The specific epithet grallaria is from Modern Latin grallarius meaning "stilt-walker". Four subspecies are recognised: F. g. grallaria (Vieillot, 1818) – tropical western Pacific Ocean, breeding on Lord Howe Island and the Kermadec Islands F. g. leucogaster (Gould, 1844) – south Atlantic and south Indian Oceans, breeding on Tristan da Cunha, Gough Island, Île Saint-Paul and Amsterdam Island F. g. segethi (Philippi & Landbeck, 1860) – southeast Pacific Ocean, breeding on the Juan Fernández Islands and the Desventuradas Islands F. g. titan Murphy, 1928 – south Pacific Ocean, breeding on Easter Island The white-bellied storm petrel of the southern hemisphere is a poorly understood pelagic species showing morphological differences and varied colour phases; it is easily confused with similar species of black and white storm petrels. Subclassification of the genus Fregetta has been described as "tentative" awaiting the clarification of further study, in particular genetic studies. The large degree of speciation observed amongst storm petrels may relate to remote island-nesting patterns associated with specific water types. Description The species is characterised on colour patterns, the condition of the nasal tubes, tail shape, structure of claws, and proportions of the leg bones. Fregetta spp. have their plumage black above, white below, and white upper tail coverts, nasal tube free at end and upturned, half culmen in length; tarsus booted in front, webs black, basal joint middle toe flattened, and claws blunt and flattened. The white-bellied storm petrel is a small bird, around in length with a wing span of , tubenose, with a fine black bill, square tail, and polymorphic patterns of black, grey, and white plumage. As the name suggests, the upper parts are dark and the underparts are light coloured with many variations in plumage observed including a largely dark variant. Its legs are long (grallae being