CHECKLIST OF ALASKA BIRDS 24th edition—2018 As of 1 January 2018 the list of avian taxa known in Alaska included 521 naturally- occurring species in 67 families and 21 orders. Phylogenetic sequence, limits of orders, families, and genera and English and scientific names of species follow The Check-list of North American Birds (7th ed., American Ornithologists’ Union 1998) and supplements (through 2017). Founded on archived specimens, the Alaska checklist increasingly includes new species known in Alaska only from (archived) photos, videotapes, and/or audio recordings. An appended ‘unsubstantiated’ list comprises an additional 21 species —including two species pairs—attributed to Alaska without specimen or photo substantiation.