Sheathbill

1. Either one of two species of birds composing the genus Chionis, and family Chionidæ, native of the islands of the Antarctic seas.
   

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.