The Collaborative International Dictionary
Sheathbill \Sheath"bill`\, n. (Zo["o]l.) Either one of two species of birds composing the genus Chionis, and family Chionid[ae], native of the islands of the Antarctic seas.
Note: They are related to the gulls and the plovers, but more nearly to the latter. The base of the bill is covered with a saddle-shaped horny sheath, and the toes are only slightly webbed. The plumage of both species is white.
Wiktionary
n. Either of two species of scavenging birds in the family ''(taxlink Chionididae family noshow=1)'' which breed only on the Antarctic Peninsula and subantarctic islands.
Wikipedia
The sheathbills are a family of birds, Chionididae. Classified in the wader order Charadriiformes, the family contains one genus, Chionis, with only two species. They breed on subantarctic islands and the Antarctic Peninsula, and the snowy sheathbill migrates to the Falkland Islands and coastal southern South America in the southern winter; they are the only bird family endemic as breeders to the Antarctic region. They are also the only Antarctic birds without webbed feet.
Usage examples of "sheathbill".
The few resident birds, the curious teal, the blue-eyed shag, perhaps the sheathbill, could scarcely find room to turn, and Stephen himself had to walk very carefully not to step on eggs or plunge into the burrows made by the countless whale-birds.
They had increased in number quite remarkably these last days - skuas, whalebirds, albatrosses and petrels of different kinds, sheathbills, terns - and he had noticed that they appeared to be travelling to or from some fixed point to the north.