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Today on Animal Fact Files we’re discussing sheathbills. These Antarctic birds get their common name from the sheath that covers the base of their bill. There are two described species: the black-faced sheathbill and the snowy sheathbill, although this common name is a bit contentious. Technically speaking, both sheathbill species are almost entirely white in color, so referring to the snowy color of one and not the other is a bit misleading. Some scientists suggest calling the snowy sheathbill the pink-faced sheathbill instead. Either way, their common names come entirely from their appearance.

Sheathbills are strange birds in that they live in Antarctica and its surrounding islands but they do not have webbed feet. Even the brown skuas that patrol the skies there and are known for eating penguin chicks sport webbed feet, but sheathbills spend most of their time walking and they do so on chicken-like feet. In fact, these birds are about the size of a chicken, reaching about 14 inches, 35 centimeters, in length with a two and a half foot, 78 centimeter, wingspan. Unlike chickens, male and female sheathbills look identical. They weigh about a pound, 450 grams, although they can nearly double this when they’ve had a lot to eat.

These snowy birds are generalists meaning they eat just about anything and everything. They’re scavengers and dine on seal and bird carcases left behind by the skuas and gulls. Sheathbills also procure their own food by scraping algae off the surface of rocks and digging up invertebrates such as beetle larvae or picking limpets off hard surfaces. They also steal food from other animals such as penguins. When a penguin parent returns from a hunting trip with a gullet full of krill for their chick, a sheathbill will startle the parent penguin in an attempt to make the other bird spill its meal which the sheathbill then swoops in and gobbles up. Both sheathbill species spend most of their time on rocky shores where penguins or seals hang out. Here they can collect other opportunistic food items such as seal afterbirth and penguin poop.

The rocky shore also provides the sheathbills with nesting grounds, and they reproduce around the same time as the animals they roost near. They prefer places with rocky outcrops which they can build their nests under. Having a roof helps protect their chicks from the weather and potential predators such as skuas. Sheathbills maintain a partner throughout the breeding season with both parents helping to raise the chicks. They have one to four white and brown speckled eggs per nest, although typically only one baby survives to independence. The eggs are incubated for about a month and the chicks leave the nest around two months old. It takes a few years for them to start producing their own chicks, and in that time they may take some trips around the world.

The black-faced sheathbill is a resident bird. It remains on the Antarctic islands in the Indian ocean that it inhabits. The pink-faced sheathbill, however, is migratory. These birds spend their winters further north, usually staying on continental southern South America and its islands, but not always. Some have been found as far as France! It's believed that pink-faced sheathbills use ships to move around. When they migrate, they often land on icebergs to take breaks, but sometimes they land atop a ship instead. This is how they end up moving much further off course than their average range. One downside to this is that it puts the birds in close proximity to fishing gear which they can become entangled in.

Although these birds are chicken-sized, they're described as walking around like a pigeon; they even have that top-heavy look to them. They spend most of their time in the ground, only flying when migrating, foraging, or when startled. In fact, sheathbills will evacuate their bowels if something startles them too much, so watch out!

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