American Oystercatcher Working Group

How to Read Band Codes

Reading band codes—also called field readable bands—can be a fun challenge. To successfully read a code you must record the orientation of the code as well as read the characters. Happily, nearly all birds with field readable codes on their bands have the same code on both bands. Although there are exceptions, in most cases, if you can read the two- or three-character letter/number code and identify the band color, we will be able to positively identify the individual bird.

Code Orientation

Code orientation refers to the orientation of the entire code, not the individual letters. Band codes may also be oriented horizontally (below left, which is 30) or vertically (below right, which is A1).

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In some cases vertical bands were applied “upside down,” but the correct orientation and character order can still be determined.

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There is another type of vertical band in which the characters are read vertically, from top to bottom, as in the photo of “03” below. Though the two individual characters are oriented horizontally, because together they are read vertically, the code’s orientation is vertical

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Some birds may have a horizontal code on a flag on one leg and a vertical code on a band on the other leg, as in the photo of dark green “CC3″ below. The orientation of these bands should be reported as “both” since one band is read vertically and one is read horizontally.

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In 2013, a new type of band began to be used. It incorporates three characters arranged in a triangular configuration. The code orientation for this type of band orientation should be reported as “triangle.”

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Reading the Codes

Bands may be engraved once or twice with a two- or three-character code. This allows the code to be seen from any angle, but can lead to confusion over which letter/number comes first when reading horizontally-oriented codes or triangle-configuration codes. Therefore, it is important to determine the order of the characters of the code so as not to confuse LA with AL or A68 with 6A8.

Two-character codes, and three-character codes on flags, are read left-to-right.  Three-character triangle codes are read top-to-bottom then left-to-right.  Therefore in the photo above of the triangle-coded band, the correct reading of the code is “A68″.  The code in the photo below is “CFU”.

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To facilitate correctly reading a code, in many cases two-character-code bands will employ a dot or an underline.  An underline indicates that the underlined letter or number is the first character, as in dark green JP below.

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Other bands may use a dot.  In the photo below, the dot separates the replicated engraved codes and shows that the E is the first element of the code, even though on the right-hand band the characters are in the order “8E”. Note also that it is not possible to tell if the character on the right band is an E or a B, but taken with the left-hand band, it can be determined to be an E.

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When there is no dot or underline, observers must look for the seam of the band to separate the replicated characters. The photos below show a green band inscribed with the code “N5”. The photo on the left shows the code in the correct order. The photo in the center shows the band turned so the code appears backward as “5N”. The dot in the center separates the characters and shows that the N is the first element of the code. You can also see that the seam separates the characters correctly in the photo on the right.

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In this photo the band on the right leg looks like “V5″, but if you look closely you will see the band seam which indicates a separation between the codes. In all cases the characters are closer together when viewed in the correct order, which also helps determine the correct way to read the band. You can see this in the photo of “5V” below as well as on red E8 and dark green JP above.

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As was stated above, although most oystercatchers have the same code on each of their upper bands, not all do. Do not assume that the same color and code are on both upper legs. Only report what you see. You can view examples of the current banding schemes in the column on the left above to see exceptions.

Finally you may notice a metal band, such as on the lower right legs of orange KC and black CR below (and the lower left leg of dark green JP above). The metal bands have a unique 8- or 9- character code on them, but these are not typically readable in the field. Because of the field readable color bands, the metal band’s code is not needed, though noting its location can be helpful.

Band placement

Band placement

All of these details can be difficult to discern in the field, but it is usually possible to do so with careful observation. One or more photos of a banded bird can be very useful in determining the band color, code, and location of the band on the leg. You can upload photos of your bird when you enter a new record. As you fill out the banding form, the image will provide you with additional explanations and photographic examples of the different types of bands. Be sure to click on them if you are unsure of what is wanted or if you are new to using the form.

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