Caspian Tern is ringed!

Just noticed whilst sorting through my Caspian Tern pictures that it has a red/burgundy ring on its right leg!

Update: An email from a friend this evening (Thursday) told me that "there are six Caspian Tern projects listed - see http://www.cr-birding.be/ - none that specify such things use red rings. They would generally have digits as well and I see none on your image. My bet is that this is perhaps a discoloured, tarnished metal-ring......"

See discussion on this here: http://www.birdforum.net/showthread.php?t=203527

Update: Friday 24th June. I have also had lots of replies and very kind help on the birdforum thread above and the most interesting theory as to this birds movement/origin comes from an email Lee Evans received:

''Hello Lee,
In Europe Caspian Terns with colour rings have been ringed in Sweden in the 1970's. No birds with that type of colour rings have been seen during many years. Since a couple of years birds have been ringed in Finland (yellow), Sweden (blue), Italy (yellow) and Russia (black). I do not know of any scheme with red rings. It is usual to use one colour ring and one metal ring on any bird. I have been reading rings of Caspian Terns on migration in The Netherlands during several years. Besides about 200 different individuals with metal rings I have only seen a few colour-ringed birds from Finland. Many of the metal rings of the birds I have seen are reddish, that has to do with the fact that these birds winter in Western Africa. This is also the case with rings on Black-tailed Godwit. When only one ring has been seen on the legs of the UK-bird it is very likely such a bird.

Best wishes,
Trinus Haitjema (Estonia)''

I also received an email from Tony at the Avian Demography Unit, South Africa who said the following:

"Dear Penny

The ring certainly looks like a metal one, either tarnished or with some
sort of metal colouring (there is a process that can do that). It is not a
South African ring as our engraved ones are white on bright red background.
The chances of one of our birds reaching the northern hemisphere are very,
very remote. Most Caspians are ringed in Sweden and Finland in Europe but I
am not sure if ringing is also carried out in West Africa (to where European
Caspians repair during the non-breeding season). Sorry that I cannot be of
more help. Try those two ringing authorities.

Best wishes

Tony"

See this picture and more on my Caspian Tern post on 18th June.