U

Dark-blue ring with white three alpha code, starting letter 'U' (on left leg) and BTO metal (on right leg).

note 1 : birds ringed on the Farne Islands, Northumberland, UK.

note 2 :

Yellow ring with a black four-alpha-numeric code.

note 1 : used codes are : UA01…, UB01…, UC01, ...

note 2 :

Dark-blue ring with a white four alpha-numeric code, starting letter "U".

note 1 : used codes are :
* U/number/number/number
OR
* U/letter/number/number
OR
* U/letter/letter/number
OR
* U/number/number/letter

note 2 :

Dark-blue ring with a white four alpha code starting letter "U".

note 1 :

Yellow ring with a black three alpha-numeric code, starting letter "U".

note 1 : birds ringed in Basque Country.

note 2 :

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 :

Orange ring with a black 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 : birds ringed during 2019.

note 3 : only used U00 to U17.

note 4 :

Yellow neckband with a black four alpha-numeric code, starting letter "U".

note 1 : UT00, UT01-UT99, UU00, UU01-UU99, UY00, UY01-UY99.

note 2 :

Yellow ring with a four alpha-numeric code, starting letter "U" followed by a three numeric code or from 2023 onwards : yellow U + letter + 2 numbers.

note 1 : used codes are U100- U999.

note 2 : used codes are UA00 ...

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 :