Dichotomous keys

I have always liked the sound of the term “dichotomous keys”. I have also long been fascinated by how these keys allow for the identification of living organisms via a series of paired choices. Dichotomous keys are forerunners of the digital age, where it is all about yes or no, 1 or 0.

While bird identification guides have largely abandoned dichotomous keys, they are certainly of historical interest and they continue to be essential for scientists. So here is a look at some dichotomous keys that include the California condor or its nest.

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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.

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