Black ring with a white 3 alpha code.
note 1 : letter "R" always as second or third letter.
note 2 : during 1998 some 350 pulli have been ringed.
note 3 : from '98 on pulli are c-ringed on left tarsus and metal ringed on right tibia, while birds ringed during winter are c-ringed on right tarsus and metal ringed on left tibia.
note 4 : during summer 2000, in the colony of Oye Plage (France) 279 juv. Black-headed gulls have been ringed with a black ring.
note 5 : during 2006 and 2007 the following codes will be used : R00A till R99Z, excl. letters B, D, F, G, I, O ,Q.