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 Ornithology.

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 Brief History of English Bird Names and the AOU (now AOS) – Ornithology 2022

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