Lesser Black-backed Gull

Black ring with a white two alpha code.
Black ring with a yellow two alpha code.

note 1 : used codes are with a ":" or a "+" or "=" between the two letters.

note 2 :

White ring with a black two alpha code.
White ring with a blue two alpha code.
White ring with a red two alpha code.
White ring with a green two alpha code.

note 1 : used codes are with a ":" or a "+" or a "=" between the two letters.

note 2 :

Blue ring with a white two alpha code.

Blue ring with an orange two alpha code.

note 1 : used codes are with a ":" or a "+" or a "=" between the two letters.

note 2 :

Orange ring with a black two alpha code.
Orange ring with a white two alpha code.
Orange ring with a green two alpha code.

note 1 : used codes are with a ":" or a "+" or "=" between the two letters.

note 2 :

Yellow ring with a black two alpha code.

note 1 : used codes are with a ":" or a "+" or "=" between the two letters.

note 2 :

Red ring with a white two alpha code.
Red ring ring with a black two alpha code.

note 1 : used codes are with a ":" or a "+" between the two letters.

note 2 :

Combination of 3 c-rings (on right leg) and white ring over metal ring (on left leg).

note 1 : the 3-ring combination has been used between 1981 and 1984 with birds ringed at Walney Island as pulli or at Plank Lane Tip, Leigh, Greater Manchester, UK, as free-flying birds.

Combination of 3 c-rings and metal ring (2 on each tarsus) (one bears a horizontal stripe).
Combination of 2 c-rings.

note 1 : Adults: maximum two rings on each tarsus.

note 2 : pulli: one colour-ring which indicates the year; adult: one colour ring plus an additional colour ring with a horizontal line.

note 3 : 

Combination of 3 c-rings (on right leg) and red ring over metal ring (on left leg).

note 1 :

Combination of c-rings.

note 1 :