Terns

species: 
Black Tern
scientific name: 
Chlidonias niger
notes: 

Orange ring with a black three alpha-numeric code : letter/number/number.

note 1 : used letters are :  A, C, E, H, K, L, M, N, P.

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