Wilson’s Storm Petrel

Identification

Wilson's storm petrel is a tiny seabird, measuring just 16–18.5 cm in length with a wingspan of 38–42 cm, making it slightly larger than the European storm petrel. The bird is essentially dark brown across all plumages, with distinctive white on the rump and flanks. In flight, the feet extend just beyond the square-ended tail. A key distinguishing feature from similar species is the diffuse pale band along the upper wing coverts and the lack of a distinctive white underwing lining that the European storm petrel displays. Pre-breeding individuals show characteristic yellow webbing between the toes, marked with black spots.

Range & Habitat

Wilson's storm petrel is one of the world's most abundant bird species, with a circumpolar distribution primarily in southern hemisphere seas, extending northward during northern hemisphere summer. The species breeds on Antarctic coastlines and nearby islands such as the South Shetland Islands during the austral summer. Outside the breeding season, it remains strictly pelagic, moving into northern oceans during the southern hemisphere's winter. The bird is much more common in the north Atlantic than the Pacific, with notable seasonal abundance documented off eastern North America, the Isles of Scilly, and around Great Britain.

Behaviour & Diet

This petrel exhibits more direct gliding flight than other small petrels, flying low over the sea surface and characteristically pattering on the water as it feeds. Its unique fluttering and hovering flight often occurs with wings held high, allowing it to soar on wave-generated breezes while using its feet for stability. Wilson's storm petrel is highly gregarious, frequently following ships and fishing boats, and produces soft peeping sounds while feeding. The species predominantly feeds on planktonic invertebrates near the surface, occasionally taking small fish from the family Myctophidae.

At breeding colonies, the bird is strictly nocturnal to avoid predation by gulls and skuas, avoiding land on clear moonlit nights. It nests in rock crevices or small burrows close to the sea, laying a single white egg. Both parents tend the nest and chick, with fledging occurring after approximately 60 days. At just 40 g on average, it is the smallest warm-blooded animal that breeds in the Antarctic region.

Best Time & Places to See It

Wilson's storm petrel is difficult to observe from land due to its strictly pelagic nature outside breeding season and remote breeding locations; it may only be pushed into headlands during severe storms. However, pelagic boat trips offer the best opportunity for sightings. The species is common off eastern North America during northern summer months and shows seasonal abundance in suitable European waters, particularly around the Isles of Scilly and Great Britain. The bird's gregarious nature means that locating one individual often leads to encountering others.

Photography Tips

Photographing Wilson's storm petrel requires patience and access to pelagic boat trips, as land-based observation is nearly impossible. The bird's small size, dark plumage, and habit of flying low over the water surface present significant challenges. Look for the characteristic white rump and flanks against the dark brown body, and note the diffuse pale band on the upper wing coverts. The bird's tendency to follow ships can provide closer viewing opportunities. Early morning or late afternoon light will help distinguish the subtle plumage details, particularly the white rump patch that is key to field identification.