Antarctic TernSterna vittataWhere and when to see them

The Antarctic tern is a pale seabird with a black cap, red bill and deeply forked tail, breeding around the Southern Ocean. Its range includes Antarctic and subantarctic islands, with regional populations differing in seasonal movements. It shares some waters with the Arctic tern but does not make that species' regular pole-to-pole migration. Coastal observers may notice its sharp calls and hovering flight before recognizing the finer identification features.

Size

31-38 cm body length

Weight

150-180 g

Lifespan

Not reliably established

Status

Least Concern

Pairs nest on the ground in small colonies or loose groups, using shallow scrapes among stones or sparse vegetation. Adults vigorously defend nesting areas, calling and swooping at intruders. At feeding sites, they hover, dip and plunge for small marine prey. Some populations remain near breeding islands, while others disperse toward southern continental coasts. Breeding schedules vary substantially across the species' broad latitudinal range and should not be generalized globally. Pairs often engage in elaborate courtship displays, including aerial chases and fish-carrying rituals. During the breeding season, they are highly vocal, using a variety of calls for alarm and communication within the colony.

• Its scientific epithet vittata refers to a banded or striped appearance.
• Some populations stay near their breeding islands year-round.
• Nests are simple ground scrapes rather than built platforms.
• Adults can recognize and vigorously challenge potential nest predators.

For Antarctic coastal travel, November through March is the practical observation period. Breeding activity in southern colonies largely falls within austral summer, but timing differs among islands. Visiting Arctic terns may also be present, so season alone is not a reliable identification tool. The austral summer is the primary breeding season, with egg-laying usually occurring from November to December and chicks fledging by February. While observing from deck, look for birds following the ship, especially during their migratory periods.

Nesting habitat includes gravel beaches, rocky coastal terraces and sparsely vegetated ground on Southern Ocean islands and parts of the Antarctic Peninsula region. Birds feed in nearby coastal waters, sheltered bays and tidal channels, and may roost on rocks or beaches outside breeding. They are often seen in areas with pack ice or drifting ice floes during the non-breeding season. Their distribution can extend to the subantarctic islands and as far north as South Africa and Australia during migration.

Small fish and crustaceans, including Antarctic krill in southern waters, form the main diet. Birds detect prey from the air and take it close to the surface. Local prey availability influences whether they feed singly, in loose groups or around concentrated food patches. In addition to fish and crustaceans, they also consume marine worms and squid. Foraging behavior often involves shallow dives from a hovering position, typically no deeper than one meter.

Common name

Antarctic Tern

Scientific name

Sterna vittata

Animal group

Birds

Size

31-38 cm body length

Weight

150-180 g

Lifespan

Not reliably established

Status

Least Concern

Identification

Compared with nonbreeding Arctic terns in Antarctic waters, breeding Antarctic terns usually show a full black cap, red bill and grayer underparts, though immature birds require care. The adult's red bill often has a dark tip, which can be a useful distinguishing feature. Compared to Arctic terns, Antarctic terns typically have shorter legs and a slightly more robust body.