Arctic Tern

Black ring with white two alpha code.

note 1 : used letters (first letter) L, P, S, T, X, Z and (second letter) A, C, E, F, H, J, K, L, N, P, R, S, T, V, X, Z.

note 2 :

Blue flag with a white two alpha code.

note 1 :  used codes are :  AA-SC.

note 2 :

Yellow flag with a black two alpha code (on left leg) and metal ring (on right leg).

note 1 : used codes : AA till ZZ.

note 2 : birds ringed in North Ronaldsay.

note 3 :

Orange ring with a black 2 alpha-numeric code (on left leg) and metal ring (on right leg).

note 1 : birds ringed in Strathclyde Region, Scotland.

note 2 : used codes are "number+letter"

note 3 : 

Orange ring with a black 2 numeric code (on left leg) and metal ring (on right leg).

note 1 : birds ringed in Strathclyde Region, Scotland.

note 2 : used codes are 01-99.

note 3 : 

Black ring with a white 2-numeric code.

note 1 : birds ringed as pulli have the c-ring on their left tarsus and 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 numbers are from 00 - 99.

note 4 : birds ringed (since 2015) as pulli from Dublin (Ireland) colonies and as adults in a post-breeding aggregation on the Dublin coast.

note 5 : 

Yellow ring with a black two alpha code (on left leg) and BTO-ring (on right leg).

note 1 : birds will be ringed at colonies on Isle of Man, British Isles from 2016 onwards.

note 2 : 

Red ring with a white two alpha code.

note 1 : used codes are : AA - ZZ.

note 2 : birds ringed on Griend, The Netherlands  form 2016 onwards.

note 3 : code to be read from bottom to top.

note 4 : 

Dark-green ring with a white two alpha code.

note 1 : used codes are AA-ZZ.

note 2 :

White ring with a black two numeric code (on one leg) and metal ring (on other leg).

note 1 :