The recent subject of use of 4-letter codes left me with a question.

Reference was made to the "USFS" codes, and an ftp address was provided
where these codes can be obtained. I got them.

There is also a list ("AOU91.TXT") of bird names and 4-letter
(sometimes 5-character) codes available on the listserv where BIRDCHAT
(another discussion list) resides.

I compared the codes used on these two lists. The rough comparison is
shown below. Following that are instructions on how to obtain these two
lists of codes.

# of
List Name Codes
-------------- -----
on "AOU91.TXT" 1957
on "USFS" 1300
on both lists 787

Now, these numbers are "rough" counts, since there are some duplicates
on the "USFS" list where alternative abbreviated spellings of some bird
names are included, and perhaps the two lists use different criteria
for which species to include. But, the general trend is that the two
lists contain different number of bird species, and each list contains
birds that the other list does not contain. That's not surprising, I
suppose. I did not check the codes with "match" to see if they all
refer to the same bird species on the two lists; I did not check the
codes which occurred on only one list to see if that species occurred
on the other list (under a different code). I don't care enough about
all this code stuff to manually read through the lists to make those
analyses --I just did what was easy to do.... finding the
codes-in-common.

However, maybe some tweeter out there _does_ know what the differences
mean, and which birders use which of the two lists when referring to one
of those many species that do not share a common code? Any insights,
tweeters?
Peter
- - - - - - -
To get the AOU91.TXT list, send email to listserv at listserv.arizona.edu
with this one-line message:
get aou91.txt (size=500k

To get the USFS list, use anonymous ftp to "ftp.im.nbs.gov" and change
directories (cd) to "pub/data/cbc/trends" to find the file "aou.lis" which
you can then GET.

These two files, in spite of hinting to being the same AOU list, are not
the same.