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Reporting colour-ringed Oystercatchers



Since 1983 Oystercatchers have been systematically studied as part of a long-term study of the University of Groningen, consequently many Oystercatchers on the Dutch Wadden Sea island of Schiermonnikoog are individually identifiable by their colour-rings. In total over 2500 individuals have been colour-banded, comprising adult breeders, juvenile and adult non-breeders, as well as fledged young. Of these banded individuals about 1000 are  probably still alive right now, of which most live on the island of Schiermonnikoog. Nonetheless, Oystercatchers colour-banded on Schiermonnikoog have been reported from all over the Netherlands, Belgium, Germany, Denmark, France, UK and Norway.

Reports of colour-ringed Oystercatchers (dead or alive) are very welcome as they are crucial to understand survival and movement patterns of Oystercatchers, which form the basis for understanding changes in population numbers. Reports are preferentially send to us using a standard form (click icon to download form). We try to send each person that reports a bird to us a life-history of that individual. An exact description of the colour-rings we use is given below.


Short history






Report colour-rings








Reports can be send (preferably by e-mail) to:

Kees Oosterbeek


Dutch Field Centre for Ornithology

P.O. Box 59, 1790 AB. Den Burg, Texel (NL)

Tel. +31 (0)222-369766

We use two different systems of colour-rings, one with bands (left) and one with letters (right):



Description of the colour-ring systems used on Schiermonnikoog: colour-rings with bars (left)


Each Oystercatcher has three different rings at three different positions (see photo):
1. A metal ring from the Dutch Ringing Centre with a unique number on it.
2. A large two-coloured barcode ring with horizontal bars of varying width.
3. A small coloured ring without bars.



To determine the exact identity of the individual we need to know 4 things:
1.The two colours of the barcode ring
We use 6 different combinations of barcode-rings, Marine rings with White bars (MW), Green rings with White bars (GW), White rings with Red bars (WR), Orange rings with Black bars (OB), Red rings with Black bars (RB) and Green rings with Black bars (GB).

2. The position and width of the bars on the code ring.
Bars can be at three different positions, top, middle, or bottom. Bars at the either three positions can be either absent (0), a thin bar (1) or a thick bar (2). The barcode is read from top to below, yielding 19 different combinations:

3. The colour of the small coloured ring without bars.
Small coloured rings are either of one or two colours. Unicoloured rings are White (W), Red (R), Green (G), Black (B) and Yellow (Y). Two-coloured rings are read from top to bottom and can be Red-White (RW), Black-Green (BG), White-Black (WB), White-Yellow (WY), Green-Yellow (GY) and White-Red (WR).

4. The position of both the barcode-ring and the small colored ring.
A birds leg consists of a tarsus (the part below the joint that looks like a knee) and a tibia (the part above the joint that looks like  knee. The code ring is always on the tarsus, the small colored ring can be either on the tarsus or tibia. The metal ring is always on the tibia, but is not of any importance.  There are six different possibilities with the same barcode and color ring, named 1-6:  

If we know combine step 1-4, we can identify the individual on the photograph below:

1. The barcode-ring is White with Red bars: WR
2. There is thin horizontal bar on the top of the barcode ring and no bars in the middle or bottom part of the barcode-ring: 100
3. The small color-ring is Green: G
4. The small colour-ring is at the right tarsus and the barcode-ring is at the left tarsus: 4.
(note that we take the perspective of the bird to determine left and right)

The unique identity of this individual is therefore: WR100G4


Description of the colour-ring systems used on Schiermonnikoog: colour-rings with characters

Each Oystercatcher has four different rings at four different positions (see drawing below and picture):
1. A metal ring from the Dutch Ringing Centre with a unique number on it.

2. Two large two-coloured rings with an engraved characters which is repeated three times on the ring.

3. A small single-coloured ring








Of importance are

  1. the exact position of each ring (left or right, tibia or tarsus)

  2. the exact colours (also of the engraved character)

  3. the exact character of each ring

The rings that are used:

  • The metal ring is always on the tibia (the part above the joint that looks like a knee).

  • The small single-coloured rings can be White, Yellow, Red, Green, Orange and Black

  • The character rings can be White, Yellow and Orange with a black engraved character or Red and Green with a white engraved character. The characters used are A, B, C, E, H, J, K, L, N, P, Q, S, T, Y, Z. Character rings are always on the tarsus (the part below the joint that looks like a knee).




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     last updated 12/08/07