[Tweeters] FLBC's - a mediocre system for field note taking? SLBC's a better system?

Mason Flint masonflint at hotmail.com
Fri Mar 27 12:13:49 PDT 2009

I know many are big fans of using four-letter bird codes when taking notes
in the field. Well known practitioners of this include Matt Bartels (his
nearly illegible scrawl adds new meaning to the word "code"). The system was
apparently developed by the USF&W Service ;) for bird banding. The concept
is good - why waste time writing out long bird names in a notebook when
you'd rather looking at the birds. As a software guy I'm reasonably good at
understanding coding systems but had not taken the time to learn the
four-letter coding system until recently. I wasn't starting from scratch
having had peers explain it to me. I was assured that the system is pretty
simple overall. You just need to understand a few rules:

1. Codes for names with only one word are formed by using the initial
letters: GYRE (Gyrfalcon), MERL (Merlin) etc.

2. Codes for two word names are formed by using the first two letters
of each word: BUOW (Burrowing Owl), CATE (Caspian Tern) etc.

3. Codes for three-word names where only the last two words are
hyphenated, are formed from two letters from the first word and one each
from the last two: WESJ (Western Scrub-Jay), EAWP (Eastern Wood-Pewee) etc.

4. Codes for other three words names are formed from one letter each
from the first two words and two from the last word: WTSH (Wedge-tailed
Shearwater), ATFL (Ash-throated Flycatcher) etc.

5. Codes for four word names are formed from one letter from each
word: BCNH (Black-crowned Night-Heron), BTBW (Black-throated Blue Warbler,
(BTGW) Black-throated Gray Warbler

Simple, right? J As long as you know where the hyphens are in the names of
the 957 species recorded in the ABA area you're good to go! Well.not quite.
Some of you noticed an error in coding examples above. It turns out that
using the rules above would result in two birds with the code BTGW -
Black-throated Gray Warbler and Black-throated Green Warbler. Ok, no big
deal. Just remember that exception and you're set, right? Well.not quite. It
turns out that there are more than 100 collisions like this. I'm not a
mathematician but my back of the envelope calculations shows that about 1 in
10 species seen in the ABA area are exceptions to the rules outlined above.
Worse, there are 12 three-way collisions - meaning three species would share
the same code using the rules above - and 58 two-way collisions.

I figured there must be another set of rules that define how the collisions
are handled so I searched around to find them. It turns out that the Bird
Banding Lab's rules for handling collisions are somewhat arbitrary. In cases
where one name is much more common than the other, the more 'common' name
gets the expected code and the less common one gets a different code. For
example, Barrow's Goldeneye gets to use BAGO because Barnacle Goose (BRNG)
is much less common. When both species are common, neither gets the expected
code and each species gets a different, unique code.


While I'm sure that everyone on Tweeters is more than capable of memorizing
all of the exceptions and never making a mistake in coding, others may not
be as smart. As I looked into this more online I found that there's a pretty
robust debate regarding the use of FLBC's. A critique by a guy named John
Shipman can be found here:
http://infohost.nmt.edu/~shipman/z/nom/bblcrit.html. He argues that
erroneous coding is quite common even in scientific settings. Imagine a
field scientist mistakenly using CAWR for Cactus Wren instead of CACW.
Others using those records for study would be using bad data.

The downside of a recreational birder making a mistake isn't as big but as
bird records are increasingly shared on the Web the cumulative effect of
small errors here and there could be significant.

A better way?

Mr. Shipman and others recommend a coding system using six letters that has
big advantages. The true test for me was whether I could read the rules
once and automatically know how to correctly code 99% of ABA birds.

SLBC's are simpler. No worrying about whether names are hyphenated or not.
Just remember four rules:

1. As with FLBC's, codes for names with only one word are formed by
using the initial letters up to six: GYREFAL (Gyrfalcon), MERL (Merlin)

2. Codes for two-word names are formed from the first three letters of
the first word and the first three letters of the last word. Hyphenated word
are always treated as separate word: BUROWL (Burrowing Owl), CASTER
(Caspian Tern) etc.

3. Codes for three-word names are formed from the first two letters of
each word: WESCJA (Western Scrub-Jay), EAWOPE (Eastern Wood-Pewee) etc.

4. Codes for four-word names are formed from the first letter of each
of the first two words and the first two letters of the last two words:
BCNIHE (Black-crowned Night-Heron), BTBLWA (Black-throated Blue Warbler),
ATTOWO (American Three-toed Woodpecker)

Better yet, six letters reduces the number of collisions from over 100 to 9.
Better yet, when there are collisions the six letter system never uses the
"expected" code for either species to avoid the confusion in the FLBC system
where sometimes one species uses the "expected" code and in other cases
neither do. In these cases each is given a code that clearly differentiate
them from each other. It could be just me but remembering nine collisions is
a lot easier than remembering 100. A full list of SLBC's can be found here:

For the record, the collisions and proper codes using the six-letter system


Right: BRDOWL (Barred Owl

Right: BRNOWL (Barn Owl)


Right: BKBWAR (Blackburnian Warbler)

Right: BKPWAR (Blackpoll Warbler)


Right: BTGYWA (Black-throated Gray Warbler)

Right: BTGNWA (Black-throated Green Warbler)


Right: COREDP (Common Redpoll)

Right: COREDS (Common Redshank)


Right: GNBRMA (Green-breasted Mango)

Right: BYBRMA (Gray-breasted Martin)


Right: LEACSP (Leach's Storm-Petrel)

Right: LEASSP (Least Storm-Petrel)


Right: PALMWA (Palm Warbler)

Right: PALLWA (Pallas's Warbler)


Right: WILSWA (Wilson's Warbler)

Right: WILLWA (Willow Warbler)


Right: YBREBU (Yellow-breasted Bunting)

Right: NBROBU (Yellow-browed Bunting)

If you've made it this far you're hardcore. This is where I ask for people
much more knowledgeable than me to explain why the FLBC system is superior
and point out drawbacks to the SLBC system that I don't see.


Mason Flint

Bellevue, WA

More information about the Tweeters mailing list