The Uniqueness of Colour Rings.

[Andrew]

I have often wondered how unique a colour ring sequence on a bird is?

I know there are so many variables that make it highly improbable that the way a bird is ringed can be repeated by a different ringing project.

For example, the bird species for a start then the orientation of which leg is ringed, the colours used and the sequence plus other factors.

There is however a slim chance say a Black-tailed Godwit was ringed in Iceland the exact same way as in Scotland if there is no system of control.

So my question is do ringers have a method of avoiding this by registering colour sequences in advance to avoid others using such sequences or what?

[tomjenner]

I don't know the system exactly, but the BTO controls the colour ringing in the UK to ensure that there is no overlap between ringers. I don't know if they coordinate between countries, but I know that individuals do that themselves. A friend works on large gulls and coordinates with other European gull ringers to reduce repetition (though in his case the large colour rings have numbers). Generally, colour rings without numbers are designed for use on small local studies of behaviour etc, rather than for migration studies, where it would get far too complicated.

Tom

[Mark Grantham]

The BTO does indeed coordinate the issuing of colour-ring schemes for a whole range of species in Britain & Ireland. There are also a set of species coordinators who do the same for species groups at a flyway level:

waders - Wader Study Group
big gulls - Peter Rock
small gulls - Kjeld Pedersen
wildfowl - Wildfowl and Wetlands Trust

This ensures that there aren't any overlaps or duplications in ring combinations, and the coordinators also match sightings up to ringers.

At the national level, the BTO does check that for migrants colour ring sequences don't clash with any in Europe that are registered at www.cr-birding.be

This isn't a foolproof system, but it works OK a majority of the time, and the results can be quite remarkable.

Mark Grantham
BTO Ringing Unit

[Andrew]

Thanks for the replies Mark and Tom. Much appreciated.