When I began my study of old publications about birds, I noted that numbers often accompanied the scientific and/or vernacular species names of bird species.

The most-commonly encountered species numbers are those created by the American Ornithologists’ Union (AOU) in the late 19th century. In this numbering system, the California condor is 324.

Here is some bibliographic history of species number 324.

In the first 2 editions of the AOU’s check-list of the birds of North America (1886, 1895), entries for each species begin with the AOU’s species number. For example, this is the entry for the California condor in the 2nd edition:

01 Entry - AOU 2nd

(The 4 pairs of letters and numbers in brackets refer to other books and the corresponding page numbers that list the California condor. The update in red pencil was in this book when I acquired it.)

Some publications adopted the AOU’s format of leading species entries with the AOU species numbers. For example, the California condor entry begins with 324 in Irene Grosvenor Wheelock’s Birds of California. Here is the title page of this notable book:

02 Title page - Wheelock 1904

In other publications, the AOU’s species number was included, although not as the 1st element of the species entry. Examples of the various formats may be found in:

Evermann, Barton W. “A List of the Birds Observed in Ventura County, California”. Auk. January 1886.

Bendire, Charles. “Life Histories of North American Birds with Special Reference to Their Breeding Habits and Eggs”. Special Bulletin [United States National Museum] 1. 1892.

Grinnell, Joseph. “Check-List of California Birds”. Pacific Coast Avifauna 3. 1902.

Editions 3-6 of the AOU check-list (1910, 1931, 1957, 1983) began species entries with the scientific and vernacular names followed by the AOU’s species number. For example, this is the entry for the California condor in the 4th edition:

03 Entry - AOU 4th

Other publications continued to include AOU species numbers through at least the 1960s. For example:

Alcorn, Gordon D. “Checklist of Birds of the State of Washington”. Occasional Papers [University of Puget Sound, Department of Biology] 17. 1962.

The AOU species number for the California condor was given as 3240 in a government report:

Bird Banding Laboratory. Steps to Improve Schedule Processing. Fish and Wildlife Service. 1988.

The extra digit allowed new species and sub-species to be wedged into the AOU’s numbering system.

In 1990, Distribution and Taxonomy of Birds of the World by Charles G. Sibley and Burt L. Monroe, Jr. was published by Yale University Press. This book provides species numbers for all the world’s bird species, largely adopting the AOU’s numbers for North American species. Indeed, the California condor is listed as 324, more than a century after it was first given that number.

As reported in its preface, the 7th edition of the AOU check-list (1998) dropped the use of species numbers entirely:

04 Entry - AOU 7th

I was surprised that the use of species numbers reached its peak at the end of the 19th and beginning of the 20th centuries. If anything, I would have thought that species numbers would be more common today, in this age of computers. But the proof is in the publications (of which I reviewed many dozens to prepare this post).

A post related to this one is Code names. For more on Irene Grosvenor Wheelock and her Birds of California, see the posts Women of the saga and Field guides: 1904-1950.