sheathbill /ˈʃiːθˌbɪl/

• 1. 

  N either of two pigeon-like shore birds, Chionis alba or C. minor, of antarctic and subantarctic regions, constituting the family Chionididae: order Charadriiformes. They have a white plumage and a horny sheath at the base of the bill 鞘嘴鸥