Common Tern

Light-green ring with a white three alpha code, starting letter "Y".

note 1 : used codes are YAA-YZZ.

note 2 :

Dark-green ring with a white three alpha code, starting letter "Y".

note 1 : used codes are YAA-YZZ.

note 2 : 

Blue ring with a white three alpha code, starting letter "Y".

note 1 : used codes are YAA-YZZ.

note 2 : 

Orange ring with a three alpha code, starting letter "Y".

note 1 : used codes are YAA-YZZ.

note 2 : 

Orange ring with a black three numeric code.

note 1 : 

Black ring with a white three alpha code, starting letter "Y". 

note 1 : 

Yellow ring with a three alpha code, starting letter "Y".

note 1 : used codes are YAA-YZZ.

note 2 : in a not-agreed project, used codes are :  letter "M" / letter / letter.

note 3 :

Dark-blue ring with a white 3 alpha-numeric code : letter U followed by 2 numbers (on left leg) and metal ring (on right leg).

note 1 : birds ringed in Leicestershire, UK.

note 2 : used codes are U00-U49.

note 3 : birds ringed during 2018.

note 4 :

Dark-blue ring with a white three alpha-numeric code, starting letter "Z" (on one leg) and metal ring (on other leg).

note 1 : used codes is : letter "Z" / letter / number.

note 2 : 

White ring with a black three alpha-numeric code.

note 1 : letter 'L' on first, second or third position. Other two digests are numbers.

note 2 : birds ringed in the Dutch inland.

note 3 :