Checklist of the avian diversity of Alaska: subspecies, breeding status, and taxonomy
Alaska is more than just a state. It constitutes the entire northwestern shoulder of North America. A vast area, it represents the eastern half of Beringia, a pivotally important area for the exchange of New and Old World avifaunas and for high-latitude avian endemism. It hosts breeding migrants from all seven continents, including tens of millions of birds from Asia.
Its geographic size and position on the globe, the diversity of its aquatic and terrestrial habitats, and its dynamic history of climatic and habitat fluctuations have produced a diverse assemblage of bird species and subspecies. The region’s high latitude causes extreme annual seasonality, making migration a predominant life-history strategy among the state’s birds. With migration, especially long-distance migration, comes enhanced dispersal, increasing the likelihood of vagrancy and colonization. The historic climatic dynamism of the Pleistocene continues today and into the future with global warming, which is occurring about four times faster in the Arctic. These changes affect avian occurrence and distributions in multiple ways, through habitat changes, but also through phenological release. Together, these drivers explain not only the current diversity of Alaska birds, but also in part why we expect Alaska’s avian diversity to continue to grow over time.
The starting point for this list is the 7th edition of the American Ornithologists’ Union (now American Ornithological Society) Check-list of North American Birds and supplements through 2023 for phylogenetic sequence and the limits of families, genera, and species. As outlined elsewhere, we no longer follow this list. For subspecies, the starting point is Gibson and Withrow’s (2015) Inventory of the Species and Subspecies of Alaska Birds, 2nd edition and two subsequent reports of the Alaska Checklist Committee (in 2018 and 2023). The Alaska Checklist Committee has been instrumental in collating, assessing, and publishing new records of Alaska birds. Designation of status (rare, casual, accidental) at the species level follows this committee’s Checklist of Alaska Birds, 31st edition (https://shorturl.at/mkQto). Changes from these starting points are based on published evidence and are referenced and explained. The breeding status, based on primary literature and/or additional sources, for all taxa is also given; this is the first time this has been done.
Alaska’s avian checklist has grown at a remarkably steady average of 3.5 species per year since the mid-1900s and shows no sign of reaching an asymptote. Gabrielson and Lincoln’s seminal work on the birds of Alaska in 1959 discussed 311 species of birds, and that number has grown steadily through time. This checklist of Alaska’s birds now includes 549 species and an additional 119 subspecies. Of these 549 species, 55 are rare, 160 are casual, and 85 are accidental; 234 species regularly breed within the state (with an additional 75 regularly breeding subspecies). An additional 38 species have at one time or another bred within the state, and 8 probably have, but are not here considered a normal part of the nesting avifauna.
We are committed to maintaining an independent, scientifically rigorous accounting of the status of the state’s avian diversity—taxonomy, occurrence, and breeding—and greatly appreciate the widespread support and input from others interested in the birds of Alaska.
Jack Withrow, Dan Gibson, and Kevin Winker