Sheathbill: where and when to see them

The snowy sheathbill is a stocky, white coastal bird associated with the Antarctic Peninsula, nearby islands and southern South America. Although often seen walking among penguins, it is neither a penguin nor a seabird specialized for feeding at sea. Its broad diet makes it an important scavenger around animal colonies. The pale sheath covering the base of its bill gives the group its name, while pink legs and bare facial skin reinforce its unusual appearance.

Size

34-41 cm long

Weight

450-780 g

Lifespan

Not reliably established

Status

Least Concern

Sheathbills spend much of their time walking, pecking and investigating the ground around penguin and seal colonies. They may steal food, seize exposed eggs or take advantage of scraps left by larger animals. Breeding pairs defend territories and nest in sheltered rocky spaces. Outside breeding they can gather around rich food sources, and some move north as Antarctic conditions become harsher during winter. Sheathbills are known for their fearlessness and curiosity, often approaching humans and investigating bags or open containers. During the breeding season, pairs will engage in aggressive displays to defend their nesting territories, chasing away intruders with pecks and squawks.

• Its toes are not webbed, unlike those of many Antarctic coastal birds.
• The bill's basal sheath is a hard, horny covering.
• It sometimes steals food during penguin chick-feeding exchanges.
• Despite its pigeonlike appearance, it belongs to the shorebird order Charadriiformes.

November through March is the main Antarctic visitor window and a useful period for observing birds near active coastal colonies. Breeding broadly overlaps the austral summer, while some individuals leave Antarctic areas during winter and others remain farther south. Prime viewing opportunities are during the austral summer when large colonies of penguins and seals are active, providing ample food sources. While some individuals migrate north to sub-Antarctic islands for winter, others remain in ice-free areas of the Antarctic Peninsula year-round.

Rocky coasts, intertidal margins and seabird or seal colonies provide feeding and nesting habitat. Sheltered cavities among rocks are used for nests. Unlike many Antarctic birds, sheathbills obtain much of their food on land rather than ranging offshore to forage. Found exclusively in the Antarctic and sub-Antarctic regions, these opportunistic birds are strong fliers and can be seen on ice floes, particularly near whale or seal carcasses. They frequently associate with human settlements and research stations, scavenging for refuse.

The diet includes carrion, invertebrates, eggs, small chicks, fecal material and food stolen from other birds. Around penguin colonies, sheathbills exploit spilled or regurgitated food. On shorelines they also search for edible material exposed among rocks and seaweed. Their diet reflects their omnivorous and scavenging nature, including krill, mollusks, crustaceans, and marine worms found in the intertidal zone. They also actively consume placentas after seal births and prey on weak or unguarded chicks of other bird species.

Common name

Sheathbill

Scientific name

Chionis albus

Animal group

Birds

Size

34-41 cm long

Weight

450-780 g

Lifespan

Not reliably established

Status

Least Concern

Identification

Compared with the black-faced sheathbill, the snowy sheathbill has pinkish facial skin and a pale horn-colored bill sheath rather than a predominantly black face and bill. Their entirely white plumage, reminiscent of a pigeon, is distinctive among Antarctic birds, though some individuals may exhibit a faint creamy or yellowish wash. The sheathbill's unique horny bill sheath is a defining feature, giving the species its common name.