The Southern or Slender-billed Fulmar (Fulmarus glacialoides) has variously been on primary (American Ornithologists' Union [A.O.U.] 1910, 1983) or hypothetical (A.O.U. 1931, 1957) lists of North American birds. Its fluctuating status results both from acceptance versus rejection of particular records and from the recent expansion of the A.O.U. Check-list's geographic coverage to include Mexico and Central America. One searching those lists will note that the bird has also been treated under the genus Priocella and the specific name antarctica.