Terns

species: 
Common Tern
scientific name: 
Sterna hirundo
notes: 

Black ring with a white three alpha-numeric code : 
* letter "Y" / number / number.
* number / letter "Y / number.
* number / number / letter "Y".

note 1 : see also : http://www.cr-birding.org/node/5798

note 2 :
 

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): 
Black (Niger) [N]
colour-ring code (of the c-ring): 
Three alpha-numeric code (3 letters/numbers).
countries where ringed: 
Poland.