Antarctic Prion: where and when to see them

The Antarctic prion is a small, blue-gray petrel of the Southern Ocean, often seen skimming low over waves in restless flocks. Its dark upperwing pattern and pale underside are attractive but shared with several close relatives, making confident identification difficult at distance. It breeds mainly on subantarctic islands rather than the Antarctic mainland. For coastal travelers, it is principally a bird to look for from a vessel's deck.

Size

25-28 cm body length

Weight

150-200 g

Lifespan

Not reliably established

Status

Least Concern

At sea, Antarctic prions weave close to the surface, pattering with their feet and collecting small prey with the bill. Feeding flocks can change direction rapidly as birds track patches of food. On breeding islands, adults generally visit burrows at night, reducing exposure to predatory skuas. Pairs share incubation and chick provisioning. Their concealed nesting habits mean a visible colony landscape may reveal very few birds during daylight hours. Antarctic prions are highly gregarious at sea, often forming large mixed flocks with other petrels and shearwaters, especially over active feeding grounds. During the day, non-breeding birds may rest in large groups on the water's surface, particularly in calm conditions. Their nocturnal visits to burrows significantly reduce predation risk from aerial predators such as skuas and giant petrels on breeding islands.

• Prions are sometimes called whalebirds.
• Comb-like structures inside the bill help retain tiny crustaceans.
• Adults usually return to breeding burrows after dark.
• Its single chick is provisioned by both parents.

November through March provides the main practical deck-observation window on Antarctic voyages. Breeding occurs during the austral summer on suitable islands, but many birds seen at sea cannot be connected to nearby colonies. Weather and viewing distance strongly affect identification success. The austral summer is the optimal time for both pelagic observations and potential, albeit limited, shore excursions to view other wildlife in the region. During this period, prions are actively breeding and foraging in higher numbers across the Southern Ocean. Late summer and early autumn may also provide opportunities to see fledglings at sea.

Antarctic prions feed over cold oceanic and shelf waters of the Southern Ocean, including waters near the Antarctic Peninsula. They nest in burrows or rock crevices on subantarctic islands, often beneath tussock vegetation or among scree rather than on exposed continental shores. Though breeding colonies are restricted to subantarctic islands, Antarctic prions range widely across the Southern Ocean year-round, including oceanic waters further north. They prefer waters with strong upwellings that bring nutrient-rich waters and plankton close to the surface. Post-breeding dispersal can lead birds across vast stretches of open ocean.

Small crustaceans dominate, especially copepods, amphipods and krill, with small fish and squid also taken. Fine structures along the bill help retain small prey. Feeding methods include surface seizing, shallow dipping and filtering prey from water gathered near the surface. The prions' lamellate bill structure, resembling a comb, is perfectly adapted for filtering minute organisms from the water. They often feed in dense aggregations over productive waters, exploiting swarms of zooplankton. While primarily a filter feeder, they are opportunistic and will take small nekton when available.

Common name

Antarctic Prion

Scientific name

Pachyptila desolata

Animal group

Birds

Size

25-28 cm body length

Weight

150-200 g

Lifespan

Not reliably established

Status

Least Concern

Identification

A dark upperwing M, pale face and moderately broad bill suggest Antarctic prion, but separation from other prions often requires close photographs and expert review. Beyond the 'M' pattern, look for the clean grey-blue upperparts contrasted with bright white underparts, a common prion characteristic. The relatively stout bill, compared to other prions like the Slender-billed, is a key feature, especially when seen in flight at close range. Note the dark eye set in the pale face and the subtly darker cap extending just to the eye.