Rook

White ring with a black three alpha-numeric code. 

note 1 : from 2004 to 2006 in León county (NW Spain) 78 birds were ringed.

note 2 :

Dark-blue ring with a white three numeric code.

note 1 : used codes are 001-100.

note 2 :

Dark-blue ring with a white three numeric code.

note 1 : used codes are 001-100.

note 2 :

Combination of 2-3 c-rings : metal ring (on left leg) and 2 c-rings (on right leg) OR 1 c-ring above metal (on left leg) and 2 c-rings (on right leg).

note 1 : birds ringed in UK, county Cambridgeshire.

note 2 : used colours are white, green, yellow, orange, red, blue, silver; red, blue and green with white stripe.

Combination of 3 c-rings : 1 c-ring above metal ring (on left leg) and 2 c-rings (on right leg).

note 1 : birds ringed in UK, county Cornwall.

note 2 : used colours are white, green, yellow, orange, red, brown, violet, blue, silver.

Dark-green ring with a white three alpha-numeric code.

note 1 : used codes are : (letter/number/number ; letter-letter-number, letter-number-letter, number-letter-letter, number-letter-letter).
 
note 2 : 

Yellow ring with a black three alpha code.

note 1 : used codes are AAA ... ACC ... ACZ.

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

note 1 : birds ringed in the UK, county Dumfries & Galloway Region.