The North American Classification Committee (NACC) evaluates and codifies the latest scientific developments in the systematics, classification, nomenclature, and distribution of North and Middle American birds. The Committee produces the official Check-list of North American Birds as well as annual supplements to the latest edition, which are published in the The Auk: Ornithological Advances.

General Philosophy

The North American Classification Committee operates under the philosophy and procedures outlined in the Preface to the 7th edition of the Check-list. Although the committee recognizes the controversy over species concepts in ornithology, it generally adheres to the principles of the Biological Species Concept. Multiple lines of evidence (e.g., multiple genetic loci, or genes plus other traits) are favored over single data sets for taxonomic changes at species and higher levels. The committee prefers to act conservatively in its treatments of taxonomy and nomenclature; thus, proposals that suggest but do not strongly support taxonomic change, or that cause instability, may be rejected pending further data. The NACC generally requires at least two independent datasets for making changes at higher-level classifications.


The NACC operates on a proposal basis. Proposals are submitted and reviewed for taxonomic changes, English name changes, acceptance of distributional records, and other items related to the charge of the committee. Taxonomic and distributional proposals should be based on previously published data. Proposals that address English name changes should follow the Committee’s policy for English names (see below).

Members of the committee as well as non-members may submit proposals following the committee’s Proposal Guidelines. Proposals are submitted to the Chair of the committee, and sets of proposals are distributed to the committee periodically each year for discussion and voting. Proposals must receive a two-thirds favorable vote to pass. To prevent conflicts of interest, members abstain from voting on proposals for which the core data are based on research that they published or supervised.

Proposals reviewed each year form the basis for publication of the annual supplements to the Check-list. Proposals and votes may be subject to change until the annual supplement is published, if new data are brought to the attention of the Committee. Proposals that do not pass may be resubmitted at a later date if additional data are published in favor of the proposal. 

In documenting species’ distribution, the Committee generally defers to state committees and to the American Birding Association for acceptance of records. 

Current & Prior NACC Proposals

English Names

The Committee has established Guidelines for English Bird Names that it follows when reviewing proposals. Authors of proposals also should consider these guidelines when submitting a proposal that would result in an English name change. 

Additional guidelines and comments on English names can be found here:

A Guide to Forming and Capitalizing Compound Names of Birds in English – Auk 1978

Spelling rules – IOC World Bird List

Use of hyphens in group bird name – South American Classification Committee

On hyphens and phylogeny – WJO 2009

From the field

Congratulations to all of the recipients of this year's AOS awards! Our annual awards honor members for their research and volunteer work. The work of the 2020 awardees spans a diversity of ornithological disciplines from genetics to landscape ecology in a range of habitats around the world, as well as invaluable service to AOS and ornithology. This year’s slate of awardees represents just a small sample of the broad diversity of our members and the contributions they are making to the scientific study and conservation of birds. Learn more about all of them at the link in our profile! #ornithology #science #biologyThe charismatic Euphonia and Chlorophonia finches are small, colorful birds that inhabit forests and woodlands from Mexico to Brazil as well as much of the Caribbean, and how exactly they fit into the songbird family tree has been debated for 20 years. The researchers behind a paper recently published in The Auk used tissue specimens and study skins from every species in this group to generate 40 *billion* base pairs of sequence data, including nearly 5,000 loci from the nuclear genome and near-complete mitochondrial genomes for every species. This amazing dataset shows has helped resolve their relationships once and for all. It also suggests that this group likely dispersed from South America into the Caribbean and North America multiple times between 2 and 4 million years ago, lending support to a younger geological timeframe for the formation of the Isthmus of Panama than argued by some other recent studies. Photos by Daniel J. Field (University of Cambridge) and Tyler Imfeld. #ornithology #science #birds #wildlife #neotropicalbirds #taxonomy #biology #finchesOne final #NationalVolunteerWeek post! Meet Rebecca Kimball, longtime AOS volunteer and Treasurer of the society since 2015, one of the leaders helping shape AOS's future. We hope you've enjoyed celebrating Volunteer Week with us!Today for #NationalVolunteerWeek we're featuring Brian Peer, who's given his time to chair the AOS Research Awards Committee for the past eight years, leading the group that evaluates applications for Student Research Awards. Thank you, Brian!AOS is celebrating #NationalVolunteerWeek! Today, meet Kyle Horton, who volunteered his time to judge student presentations at last summer's AOS meeting in Anchorage, Alaska.Today for #NationalVolunteerWeek, meet Lori Hargrove! Lori works at the San Diego Natural History Museum and is a regular reviewer for AOS journal The Condor. Scholarly journals can't function without reviewers like Lori, who volunteer their time to read and assess the papers that are submitted.We're celebrating #NationalVolunteerWeek! AOS couldn't function without the many members who volunteer their time to assist with our meetings, publications, awards, and other programs, and we'll be introducing you to one of those volunteers every day this week. Today, meet Juita Martinez, a PhD student who helped staff the registration desk at last year's annual AOS meeting in Anchorage, Alaska!
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