White-bellied Storm Petrel
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.
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 18 to 20 centimetres in length, 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 Latin for "stilts") and a distinguishing characteristic is that the toes do not usually project beyond the tail. Plumage variation between sexes and between adults and juveniles has not been observed.