wilsons storm petrel

The adult has sooty-brown head and upperparts with darker flight feathers. There is a greyish panel on the inner art of the upperwing, formed by the paler greater coverts. The white rump contrasts strongly with the blackish tail. The underparts are sooty-black too, except the white sides of tail’s base and the thighs. Underwing and undertail are blackish. The bill is black. The eyes are dark brown. Legs and feet are black with yellow webs bordered with black. Both adults are similar in plumage, but the female is slightly larger with longer wings. The juvenile resembles adult but it often shows some white feathers on belly.

This species breeds on the Antarctic coastlines and nearby islands such as the South Shetland Islands during the summer of the southern hemisphere. It spends the rest of the year at sea, and moves into the northern oceans in the southern hemisphere's winter. It is much more common in the north Atlantic than the Pacific. Wilson's storm petrel is common off eastern North America in the northern summer and the seasonal abundance of this bird in suitable European waters has been revealed through pelagic boat trips, most notably in the area of the Isles of Scilly and Great Britain. It is strictly pelagic outside the breeding season, and this, together with its remote breeding sites, makes Wilson's petrel a difficult bird to see from land. Only in severe storms might this species be pushed into headlands.

They feed predominantly on planktonic invertebrates close to the surface, rarely plunging below the surface to capture prey. They may however sometimes take 3–8 cm long fish in the family Myctophidae.

The Wilson’s Storm-Petrel’s main call is a loud, nasal, grating aark aark given from the ground at colonies. The male utters a monotonous chatter to attract females "aark-uh-ah-ah-uh-uh". This species is usually silent at sea, but some quiet, low squeaks can be heard within the feeding flocks.
The birds may call during aerial pursuits or while flying above the nesting hole at night.

Wilson's storm petrel (Oceanites oceanicus) also known as Wilson's petrel is a small seabird of the austral storm petrel family Oceanitidae. It is one of the most abundant bird species in the world and has a circumpolar distribution mainly in the seas of the southern hemisphere but extending northwards during the summer of the northern hemisphere. The world population has been estimated to be more than 50 million pairs. The name commemorates the Scottish-American ornithologist Alexander Wilson. The genus name Oceanites refers to the mythical Oceanids the three thousand daughters of Tethys. The species name is from Latin oceanus "ocean". Wilson's storm petrel is a small bird 16&ndash18.5 cm (6.3&ndash7.3 in) in length with a 38&ndash42 cm (15&ndash16.5 in) wingspan. It is slightly larger than the European storm petrel and is essentially dark brown in all plumages except for the white rump and flanks. The feet extend just beyond the square ended tail in flight. The European storm petrel has a very distinct whitish lining to the underwing and a nearly all dark upperwing. Wilson's storm petrel has a diffuse pale band along the upper wing coverts and lacks the distinctive white underwing lining. The webbing between the toes is yellow with black spots in pre-breeding age individuals.