Common Tern

Yellow ring with a black 3 numeric code (on left leg) and metal ring (on right leg).

note 1 : used codes are : *.00 -*.99 , where * is a number.

note 2 :

White flag with a black three alpha-numeric code.

note 1 : first letters are N or P or R or S or T.

note 2 :

Blue ring with a white three alpha code : starting letter 'V'.

note 1 : used codes are VAA-VZZ.

note 2 : birds ringed since 2018.

note 3 : 

Yellow ring with a black three alpha code : starting letter 'V'.

note 1 : used codes are VAA-VZZ.

note 2 : birds ringed since 2020.

note 3 : 

Blue ring with a white 3 alpha-numeric code.

note 1 : all birds are ringed as pulli and have the c-ring on their left tarsus and a metal ring on the right.

note 2 : used combinations are : letter "P"/ number/ number OR number/ letter "P"/ number OR number/ number/ letter "P".

note 3 : used numbers are : 1, 2, 3, 4, 5, 6, 7, 8, 9, 0. 

note 4 :

Yellow ring with a black 3 alpha-numeric code.

note 1. : all birds are ringed as pulli and have the c-ring on their left tarsus and a metal ring on the right.
Those ringed as post-breeding, fledged birds have the c-ring on the right tarsus and the metal on the left.

note 2 : used combinations are : letter "P"/ number/ number OR number/ letter "P"/ number OR number/ number/ letter "P".

note 3 : used letters are : A, C, E, F, H, J, K, L, N, P, R, S, T, U, V, X, Y, Z and used numbers are : 1, 2, 3, 4, 5, 6, 7, 8, 9, 0. 

note 4 :

Dark-green ring with a white 3 numeric code (left leg).

note 1 : used codes are 300-399.

note 2 : birds ringed on Blue Circle Island, Antrim.

note 3 : 

Red ring with a white 3 alpha-numeric code : letter M followed by 2 numbers (on left leg) and metal ring (on right leg) OR number, letter M, number.

note 1 : birds ringed in Strathclyde Region, Scotland.

note 2 : used codes are M01-M99.

note 3 : 

Dark Blue ring with a white 3 alpha-numeric code : letter M followed by 2 numbers (on left leg) and metal ring (on right leg) OR number, letter M, number.

note 1 : birds ringed in Strathclyde Region, Scotland.

note 2 : used codes are M01-M99.

note 3 : 

White ring with a black 3 alpha-numeric code, starting letter "U" followed by 2 numbers (on left leg) and metal ring (on right leg).

note 1 : used codes are U.00-U.25

note 2 : birds ringed in Leicestershire, UK.

note 3 :