Sheathbills

The Chionidae family, consisting of one genus, Chionis, and two species, are unique birds known as sheathbills. They exhibit white plumage and have a distinguishing horny sheath on their stout bills, earning them their name. These birds, endemic as breeders to the Antarctic region, resemble plump doves and lack webbed feet, setting them apart from other Antarctic birds. Johann Reinhold Forster introduced the genus in 1788, and the snowy sheathbill is identified as the type species. With their white downy feathers and bare facial skin, they are adapted to their subantarctic and Antarctic Peninsula breeding grounds but migrate to the Falkland Islands and southern South America during the southern winter. Their behaviour is not unlike that of rails; they walk on the ground and fly akin to pigeons when disturbed. As scavengers, sheathbills eat a varied diet, including carrion, invertebrates, and even steal milk directly from elephant seals. They are known to be aggressive during the breeding season, often harassing penguins to pilfer eggs, chicks, or their food. Their blotchy white eggs are laid in untidy nests in rock crevices, and they prioritize self-cleaning after feeding. The sheathbill's closest relatives are the thick-knees, and genetic studies link them with plovers and other waders. The snowy sheathbill and the black-faced sheathbill are the two known species, mainly found across Antarctic and subantarctic islands. Recent research indicates that the Magellanic plover might be closely related to the sheathbills.