Gulls

species: 
Black-headed Gull
scientific name: 
Chroicocephalus ridibundus
notes: 

Blue ring with a white four alpha-numeric code : starting letter "T" followed by a white three alpha-numeric code.

note 1 :

website sighting submit: 
Ornithological Station, Museum and Institute of Zoology of the Polish Academy of Sciences.
email sighting submit: 
colour-ring type: 
Legring : one, coded.
colour-ring colour (of the c-ring): 
Dark Blue [B]
colour-ring code (of the c-ring): 
Four alpha-numeric code (4 letters/numbers).
countries where ringed: 
Poland.
Images: 
First letter/number (of the c-ring): 
T