Northern Giant Petrel

Overview

The Northern Giant Petrel is one of the largest members of the petrel family, rivaling small albatrosses in bulk, with a huge pale bill tipped in reddish-brown. It is a scavenging generalist of southern oceans, often seen feeding at carcasses alongside albatrosses.

Plumage darkens with immaturity and lightens with age, so a single population shows a wide range of brown tones, from nearly blackish-brown juveniles to paler, mottled adults with whitish heads.

Giant petrel feathers are large and heavy for a tubenose, reflecting the bird's substantial size.

• Flight feathers: Broad, strong primaries in dark brown, often with slightly paler edges; shafts are thick and pale.
• Body feathers: Mottled brown with irregular pale flecking, especially on older individuals; head and neck feathers become progressively paler and grayish-white with age.
• Distinguishing from albatross feathers: Giant petrel feathers are generally more uniformly brown and lack the crisp black-and-white contrast of most albatrosses.
• Northern vs Southern Giant Petrel: Feather color alone cannot reliably separate the two giant petrel species; the pale-tipped, reddish-brown bill color (versus a greenish bill tip on the Southern Giant Petrel) is the more reliable field distinction when the bill is present.

Juveniles are nearly uniform sooty blackish-brown all over. With successive molts over several years, the head, neck, and underparts become increasingly mottled with white and gray, producing a marbled, paler appearance in older adults while the wings and back typically remain darker brown. Sexes are similar in plumage though males average larger. Molt is protracted and can overlap with breeding activities given the bird's large size and slow feather replacement.

Northern Giant Petrels breed on subantarctic islands in the Southern Ocean and range widely over cold southern waters outside the breeding season, sometimes reaching subtropical latitudes. They are strongly pelagic but will come close to shore to scavenge at seal or penguin colonies. Movements are largely dispersive rather than a fixed migratory route, following food availability across vast stretches of open ocean.

Giant petrels are powerful, opportunistic scavengers, feeding on carrion from marine mammal and seabird carcasses as well as catching live prey at the sea surface. They fly on long, broad wings with a heavy, direct flight style compared to smaller petrels. A single egg is laid in a simple ground nest, and the young bird broods for an extended period given its large size. Their calls include low grunts and hisses, especially when squabbling over carcasses, and they can eject stomach oil defensively when disturbed at the nest.