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Committee on Classification and Nomenclature (North & Middle America)

About the Committee

The AOU Committee on Classification and Nomenclature of North and Middle American Birds ("North American Classification Committee," NACC) is an official committee of the American Ornithologists' Union whose mission is to keep abreast of the systematics and distribution of North and Middle American birds, with the purpose of creating a standard classification and nomenclature. The NACC produces editions of the "Check-list of North American Birds" as well as annual supplements to the latest edition (published in the July issue of The Auk). This classification is subject to constant revision as new data are incorporated.

Current Members

Members: R. Terry Chesser (Chair), Richard C. Banks, F. Keith Barker, Carla Cicero (co-Chair), Jon L. Dunn, Andrew W. Kratter, Irby J. Lovette, Adolfo G. Navarro Siguenza, Pamela C. Rasmussen, J. V. Remsen, Jr., James D. Rising, Douglas F. Stotz, Kevin Winker.

Technical Advisors: Normand David, Daniel D. Gibson, Michel Gosselin, Michael A. Patten.

7th Checklist and Supplements

The complete printed version of Check-list of North American Birds, 7th edition and its supplements are available to download.

General Philosophy

The NACC operates under the same philosophy and procedures outlined in the Preface to the 7th edition (pdf). 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. We generally require at least two independent datasets for making changes at higher-level classifications.

Operating Procedures

The NACC operates on a proposal basis, in which 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. Proposals also may be submitted that argue against a change recommended in the literature. Proposals typically are submitted on a case-by-case basis. Although members of the committee submit most proposals, any non-member may submit a proposal for consideration by the committee (see guidelines). Proposals are submitted to the Chair of the committee, and sets of proposals are distributed periodically (2-3 times per year) to the committee for discussion and voting. Occasionally, proposals are sent to non-member "experts" for comment. Proposals must receive a 2/3 favorable vote to pass. 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.

Guidelines for submitting a proposal


Pending Proposals
Prior Proposals

English Names

The Committee's policy on English names is stated in the Foreward to the 6th (1983) edition of the Check-list of North American Birds (pages xxi-xxiii), and is further elaborated in the Auk 124:1472, 2007 (PDF, 116KB, 1p). Additional comments on English names and the controversy over hyphenation of compound names can be found here:

"Use of hyphens in group names in birds" - South American Classification Committee
"The hyphen debate" - IOC World Bird List


The last edition of the AOU Check-list to include subspecies was published in 1957 (5th edition). For reasons of expediency, the Committee reluctantly excluded treatment of subspecies in both the 6th and 7th editions, although it continues to endorse the biological reality and practical utility of subspecies as a taxonomic rank. Subspecies that reflect biological diversity play an important role in flagging the attention of evolutionary, behavioral, ecological, and conservation biologists. After careful study, an unknown number of subspecies likely will unmask cryptic biological species, or "species-in-the-making" that constitute a significant element of newly evolving biodiversity. On the other hand, the Committee also recognizes that an uncertain number of current subspecies apply to poorly differentiated populations and thus cannot be validated by rigorous modern techniques.

Read more about subspecies and the AOU Check-list Committee

Check-lists of Other Regions

British Ornithologists' Union
South American Classification Committee

Other Links

Assembling the Tree of Life: Early Bird
Avian Tree of Life (Modern Birds)
The Birds of North America Online
History of North American Bird Names