Yeah, there's a great big scary pile of variations on the 4-code. First to
be generally standardized was the bander's code (USFW NBS). There are
discrepancies even on this. The Bander's Manual codes produced by the USFW
disagree with Pyle's _Handbook for Passerines_

Common Bushtit for example is COBU according to the feds, but BUSH according
to Pyle.

As a bander, I have adopted the USFW 4-codes for personal use. I avoid using
them in ordinary communication to others, however, opting for the full English
name. 4-codes are probably best left to personal use and computer data input
in which case the method one uses becomes moot for most of us.


>
>There is more than one system in use "out there." Those employing
>four-letter codes based on the English name of the species are deceptively
>similar to one another but use different sets of rules to derive the
>codes. Any system inevitably has a degree of subjectivity and
>>
>> according to the USFW NBS official code book:
>>
>> Trumpeter Swan = TRUS
>> Tree Swallow = TRES
>>
>> The rule is: If two birds have the same 4-code, one picks the next easiest
>> combination IN BOTH SPECIES that resolves the conflict.
>>
>>

--
*********************************** I was of three minds
* Mike Patterson, Astoria, OR * like a tree
* mpatters at orednet.org * in which there are three blackbirds.
*http://www.pacifier.com/~mpatters* -Wallace Stevens