Gulls

species: 
Great Black-backed Gull
scientific name: 
Larus marinus
notes: 

Dark-green ring with a white four alpha-numeric code (on left tarsus) and metal ring (on right tarsus).

note 1 : starting code is letter "B:" (note the colon) followed by three numbers.

note 2 : 

email sighting submit: 
colour-ring type: 
Legring : one, coded.
colour-ring colour (of the c-ring): 
Dark Green [G]
colour-ring code (of the c-ring): 
Four alpha-numeric code (4 letters/numbers).
colour-ring position (of the c-ring): 
Tarsus left.
countries where ringed: 
United Kingdom.
First letter/number (of the c-ring): 
B: