AOU Codes Discussion

When I was in college, the USFWS had an extensive research capacity, with several research stations around the country and cooperative research units at quite a few state universities. The entire capacity was moved over to the USGS during the 1990’s, if I remember correctly, with no particularly good reason ever given.

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My point there was that the “AOU list” wasn’t produced by the AOU (now the AOS, of course). IBP gave it that name because they were using the AOU checklist to determine what species they needed to include.

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Why isn’t the 6 letter code based on the scientific name used instead of a 4 letter code based on the common name.
I would think there would be less chance of duplication.

Maybe because four letters are one-third shorter than six?

And when I’m noting it in my field notes, m-dov comes more naturally to me than MODO.

Given the origin of these codes, I don’t have an answer to this question. I’m sure that 4 rather than 6 had to do with database memory issues (memory used to be much more expensive than it is now…) But the codes were first made for banders, and I would think that using the scientific name would have worked just fine. On the other hand, even back then N. American birds had a set of standardized common names that are frequently used even by ornithologists.

Interestingly, my first exposure to these kinds of codes was for vegetation surveys. Vascular plants had 4-letter codes (ACTR – Achlys triphylla; PSME – Pseudotsuga menzeisii), whereas bryophytes (then including liverworts) had 6-letter codes (EURORE – Eurhynchium oreganum; FRUNIS – Frullania nisquallensis). It wasn’t perfect, though, because there were instances where unrelated plants ended up with the same code. This was resolved by assigning numbers to those cases (LIBO2 – Linnaea borealis, because LIBO is Lilium bolanderi).

In the case of birds, they bend the rules for the 2 species. The worst pair I know of for that is Blue Grosbeak and Blue Grouse (before they were split, of course). They ended up with BLGK and BLGU, I believe.

Quiscalus nicaraguensis has one of these 4 letter codes on it’s iNat taxonomy page despite it being a Central American species, not a North American species. I’m not sure who listed it, but if it’s actually official… it needs to be changed. If it isn’t, it should be removed.

See original thread:

Yes, just flag these and/or delete - at this point, it seems clear they should be deleted.

Actually, that looks like a real AOU-code which has its own lexicon, so that one seems ok.


The AOS these days has two checklists, a N. American and a S. American one. The N. American one includes Central America, so if you search the N. American checklist for Q. nicaraguensis, you’ll find it there. Given that the IBP codes that sort of started this discussion were based on the AOS checklist, I suspect that this code is in that list.

(Whether we should be including those as names for the species involved, I’m not going to take a stand on that one.)

The USGS is owned by the USFWS, so bird banders never switched superiors, they just went to different department. Like being switched from grocery to automotive in a Walmart.

This isn’t true. They are separate agencies, but both within the U.S. Department of Interior. They aren’t even in the same operating unit.

USGS was formed so that all the major research functions of the DOI were housed within a single agency. They took over research functions from USFWS, NPS, BLM, etc. and greatly increased the department’s research capacity because of this.

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