|ring area||Croatia, Zagreb|
|observations||25675, of which 9810 are captures|
|ringed in||2007 to 2020|
We started this ringing project in 2007. Since then, around 10 000 birds have been ringed. Most of the Black-headed Gulls are ringed in the winter time on the Jakuševec rubbish tip in Zagreb, Croatia. Some are also ringed on other rubbish tips. A small number is ringed on breeding colonies. We use white rings with a 4 alphanumeric code, starting with S.