Annual AviList Update (v2026)

Black-and-red Broadbill Cymbirhynchus macrorhynchos is a striking species from Southeast Asia that is always wonderful to encounter and not particularly difficult to find. However, it does require forest, which is ever-shrinking worldwide. With this year’s update, AviList will also recognize the Ayeyarwady Broadbill Cymbirhynchus affinis as a full species. This taxon was previously treated as a subspecies of Black-and-red Broadbill but differs in substantially smaller size, paler plumage, large red spots on the tertials, and having more white in the undertail. Unfortunately the other major difference from Black-and-red is that Ayeyarwady is so rare, range restricted and poorly known that it may persist only in a few remote areas…or it even may have gone extinct more than a century ago. The revised classification was largely thanks to a careful assessment of the taxon by Berryman et al. (2025), who write “the evidence points to the species being undocumented since the NHMUK specimen of 1874, more than 150 years ago”. This case perfectly highlights why an accurate, current, and consistent taxonomy is of critical importance as conservationists around the world attempt to stem ongoing biodiversity loss. Once species limits are clarified, endeavors like the Lost Birds project can help spur birders, researchers, and explorers towards locating and learning about the world’s rarest birds before it is too late. Photo of Black-and-red Broadbill Cymbirhynchus macrorhynchos by Luke Seitz | Cornell Lab of Ornithology | Macaulay Library.

The first major revision for AviList, v2026, is now available for download and exploration via the Checklist Explorer. AviList is committed to once-annual updates in October and we are excited to announce this year’s update which showcases the hard work of numerous committees, groups, and individuals within the AviList community.

AviList was released on 11 June 2025 as a freely available consensus taxonomy for all birds of the world (AviList v2025). A minor update in June 2026 (v2025b) was released to support the Checklist Explorer, correct a few typos, and to reflect alignment progress from BirdLife International and the Cornell Lab of Ornithology’s eBird/Clements Checklist. This alignment has been a major goal, maybe the primary goal, of the AviList effort. It is now a reality that this shared taxonomic background across systems is better connecting major initiatives in bird conservation (such as the IUCN Red List and BirdLife DataZone), avian science and informatics (such as eBird, Birds of the World, GBIF), and even public outreach and engagement around birds (Merlin, Wikipedia, All About Birds, various field guides, etc.).

The AviList team has been busy behind the scenes. The team’s work in the second half of 2025 and first half of 2026 represented the initiation of Phase II for AviList. Phase I was a multi-year project to assemble partners from the three major global checklists (IOC World Bird List, BirdLife International, and the eBird/Clements Checklist from the Cornell Lab of Ornithology), two regional checklists (AOS-NACC and SACC), and additional experts from around the world. The team worked to assess over 1000 issues (see those Deliberations) and to publish a consensus checklist, all in collaboration with ongoing initiatives by BirdLife International and the Cornell Lab of Ornithology which depend on maintaining internal taxonomies to manage their data. However, both organizations have ceased independent taxonomic operations and increasingly have been orienting around the AviList effort.

Phase II has been important in two major ways. First, the teams at BirdLife International and the Cornell Lab of Ornithology continued efforts to adjust their data and databases to support gradual alignment around the consensus effort. With this update, AviList species are in 97.7% alignment with eBird; the few remaining are especially thorny taxonomic riddles that the AviList Taxonomic Committee (TaxCom) and our AviList Regional Advisory Groups (RAGs) will be prioritizing in the near future. BirdLife International will release their 2026 update in late November or December and with that we will have a sense of how far the alignment process has progressed for BirdLife (note that alignment for BirdLife is especially challenging, since its connection to the IUCN Red List requires very careful reassessment of large amounts of data, so we expect the full process to take several more years). However, with each annual update these taxonomies are converging and the benefits are multiplying for data interoperability and taxonomic clarity. Birders can also rejoice as their observations, field guides, online resources, and conversations enjoy increased alignment around a consensus.

The other major achievement in Phase II has been to expand the team and engage more specialists, which has resulted in the onboarding of multiple new committees. These include four Regional Advisory groups: for Tropical Asia (chaired by Keren Sadanandan), Australasia (chaired by Anna Kearns), sub-Saharan Africa (chaired by Gabriel Jamie), and the Palearctic (chaired by Manuel Schweizer). These groups joined two established initiatives in the Americas: the North American Classification Committee (AOS-NACC; chaired by Terry Chesser) and South American Classification Committee (SACC; chaired by Van Remsen) to work collaboratively towards researching and advancing new taxonomic proposals for assessment. It is noteworthy that AOS-NACC and SACC retain their independence, although both work collaboratively with AviList to remain in sync as much as possible. In rare cases these committees may reach different decisions, or move at a different pace, than AviList. For example, the 67th supplement split American Egret (Ardea egretta) from Great White Egret (Ardea alba), while AviList has opted to wait to try to resolve species limits in the Old World between the three taxa there (alba, modesta, and melanorhynchos). Importantly In 2026 we have also formalized a Taxonomic Sequence Committee (Martin Stervander and Gustav Asplund), an English Names Committee (chaired by Praveen J), and a Geographic Range Committee (chaired by Pam Rasmussen). The Technical Committee has expanded and especially has benefited from the involvement of Adam Jackson, who was the primary force behind the Checklist Explorer and our Deliberations pages. As we enter deliberations for v2027, the Nomenclatural Committee will again become active, and we are thrilled to welcome Sylke Frahnert as the chair for that group. These many individuals and teams helps to flesh out the vision for AviList as a highly collaborative, global effort that proactively seeks opinions and involvement from specialists at both the local and global scale. AviList is also open to assessing taxonomic proposals submitted by members of the public.

The 2026 taxonomy is available in several ways.

  • First, we continue to support formatted Excel files in both extended and short formats. The extended format includes extra nomenclatural and bibliographic fields, as well as information relating to the alignment of sister taxonomies (i.e., data and links from BirdLife International, eBird, and Birds of the World). The basic format has the core taxonomic fields that are of the most interest.
  • Second, the interactive Checklist Explorer is a great way to explore AviList. This interactive list is easily searchable and filterable by rank, order, family, genus, and IUCN Red List category (IUCN code). The “Details” section (or a click within a row) shows the full set of taxonomic information about a species, including the range, nomenclatural and bibliographic information, and more. Unique to this explorer is an option to set an alternate common name (e.g., UK English, French, German, Thai, Japanese, Zulu, or many more). These names come from eBird, which works with partners and volunteers to maintain over 117 regional versions of bird names in over 70 different languages and allows users to set those in eBird, Birds of the World, and Merlin. Many languages only translate a subset of names within a country or region (e.g., Kazakh has names for birds of Kazakhstan only) and only a handful provide a full global set of names; again see eBird’s common names page for details. This is one of the many benefits of taxonomic alignment that AviList has allowed, which facilitates the collaborative display of data resources like these names and the IUCN Red List codes.
  • Third and finally, the Checklist Explorer allows a CSV download that gives a customized version. Whatever results you display on the page itself can be exported as a CSV file right from the page and any filters you have applied will also apply in the CSV export; it is possible to download either the basic (7 core taxonomy columns plus IUCN status) or extended version (all 26 columns, as in the official XLSX file). This enables the linkage with alternate common names managed by the eBird/Merlin team at the Cornell Lab of Ornithology. This is one of the many benefits of alignment and allows AviList names to be displayed in most major languages around the world (and also supports regionalized versions for English, French, Spanish, Portuguese, and Chinese). Hopefully this helps you interact with AviList in the language you prefer!

Huge thanks to everyone involved for their work on AviList and support for the move towards a consensus taxonomy!

Astute birders have long enjoyed the challenge of separating the two subspecies of Willets Tringa semipalmata in North and South America, and this year—thanks to a detailed proposal to the North American Classification Committee and AviList—the two taxa will be recognized as monotypic species: Saltmarsh Willet Tringa semipalmata and Prairie Willet Tringa inornata. Careful observation has revealed drastically different patterns of occurrence that have helped clarify that two species are involved. Saltmarsh Willet breeds in coastal saltmarshes from Atlantic Canada to Texas and sparingly in the Caribbean; it vacates North America almost entirely and primarily winters along the Atlantic Coast of South America, with Brazil hosting much of the population. Prairie Willet, by contrast, breeds in wetlands of the Prairie Provinces, Great Plains, and Great Basin Desert and winters along both the Pacific and Atlantic coasts from Canada south to the Southern Cone of South America. When in juvenile plumage and when direct comparison is possible, the differences can be quite striking: Saltmarsh Willet (left) is smaller and browner with more distinct bars and notches on their tertials and wing coverts, while Prairie Willet is larger, grayer, and has marbled or indistinct patterning in its fresh juvenile wing coverts and tertials. Much remains to be learned about the exact distribution, and having birders and ornithologists more focused on identifying these at the species level is sure to bring additional insights in the years to come. Photo by Jeremiah Trimble | Cornell Lab of Ornithology | Macaulay Library