The avifauna of the Aleutian Islands included 376 species according to Gibson and Byrd (2007), Bird Checklists of the World (Avibase), and the American Ornithological Society (AOS) as of March 2021. Of them, 44 (12%) are year-round residents and breeders, 26 (7%) migrate to the Aleutians to breed, 18 (5%) migrate to the Aleutians to winter, 6 (2%) are non-breeding summer residents, 37 (10%) are annual through-migrants, 196 (53%) are vagrants of less-than-annual occurrence. The status of the remaining 42 is not noted by either Gibson and Byrd or Avibase. Several of the vagrants have only a single record.