Antarctic Petrel: where and when to see them

The Antarctic petrel is a boldly patterned brown-and-white seabird closely tied to the Antarctic continent and surrounding ice-zone waters. Unlike many petrels that breed on vegetated islands, it nests on exposed rock, sometimes far inland. Its striking wing pattern can be visible from a ship's deck as it banks over the sea. Nevertheless, breeding colonies are generally remote, and the species is not a predictable feature of standard coastal visits.

Size

40-46 cm body length

Weight

500-800 g

Lifespan

Not reliably established

Status

Least Concern

Antarctic petrels gather in colonies on rocky slopes and ledges, where pairs share incubation of a single egg and subsequent chick care. At sea they alternate flapping with gliding, often concentrating around productive ice edges. They take prey near the surface and can make short plunges after food. Adults defend nest sites with oily stomach contents, so disturbing colonies risks both stress to birds and contamination of nearby plumage. Antarctic petrels are known for their spectacular mass foraging events, where thousands of birds can gather at productive ice edges. They are highly colonial breeders, with some colonies numbering in the hundreds of thousands of pairs. Pairs often exhibit strong site fidelity, returning to the same nesting ledges year after year.

• It is the only living species in the genus Thalassoica.
• Some colonies lie far inland on exposed Antarctic rock.
• Each breeding attempt normally involves a single egg.
• Like other petrels, it has tubular nostrils and produces energy-rich stomach oil.

November through February overlaps colony activity and the main period of accessible Antarctic travel. Distant deck observations depend strongly on route and proximity to suitable ice-zone waters. Many important breeding areas remain inaccessible to ordinary visitors throughout the year, regardless of season. Prime viewing opportunities often coincide with their breeding season, as birds are concentrated at colonies or foraging nearby. However, large aggregations at sea can be observed during summer months when foraging along the ice edge, sometimes involving thousands of individuals. Early austral summer offers the best chance to see adults returning to or establishing their nests.

Breeding sites are snow-free cliffs, scree slopes and rocky outcrops on the Antarctic continent and nearby islands, including sites well inland. Feeding habitat lies in cold Southern Ocean waters, especially the seasonal pack-ice zone, leads and productive waters around retreating ice. Coastal breeding colonies are typically found on exposed, north-facing slopes, which allows for maximum solar exposure to melt snow. While most colonies are coastal, some significant breeding sites are located hundreds of kilometers inland in nunatak regions of the Transantarctic Mountains. These inland sites are often associated with geothermal activity, providing snow-free areas for nesting.

Antarctic krill, fish and squid form the principal diet, with their relative importance varying by locality and prey availability. Birds seize food at the surface or just below it. Concentrations of prey around sea ice can attract substantial feeding flocks. Their diet composition often reflects the abundance of krill, especially during the breeding season when energy demands are high. During winter months, when krill may be less accessible, the proportion of fish and cephalopods in their diet can increase. This dietary flexibility allows them to adapt to seasonal variations in prey availability across the Southern Ocean.

Common name

Antarctic Petrel

Scientific name

Thalassoica antarctica

Animal group

Birds

Size

40-46 cm body length

Weight

500-800 g

Lifespan

Not reliably established

Status

Least Concern

Identification

Dark brown upperparts contrast with broad white rear wing panels and a white tail with a dark tip, separating it from the grayer Antarctic fulmar. The species is medium-sized, measuring around 40-46 cm in length with a wingspan of 100-110 cm. Its distinctive flight profile, with deep wing beats alternated with long glides, can also aid identification at sea. The sharp contrast between the dark cap and the white face is another helpful field mark.