This page shows the distribution of banded Black-headed Gulls (Croicocephalus ridibundus) I have discovered in my area. The observations are mostly done on the island of Amager, but I've added the few observations I have from the Copenhagen area on the Sjælland side as well.
Most of the birds are locally banded (done by Kjeld Tommy Pedersen), but are not necessarily Danish breeding birds. Rather, I expect them to be of foreign, eastern, origin, taking that most birds are found in the winter months.
I decided to make this small piece of statistic because I found out that most of the banded birds were extremely faithful to one place only. The island is not big, ca 15 x 10 km, why it would be reasonable to expect them to be found at different localities. But that has only been the case in very few occasions. Of course, the fact that I don't see the same birds every time at the same locality indicates that they do disappear and move to other places. But apparently not to the other spots I frequently visit.
I know you can find many Black-headed Gulls at other sites, especially Kalvebod Fælled, but the places I'm covering now are places where you, on a regular basis, can get close enough to the birds to read their bands or see the bands at all.
When I started looking for banded gulls, I sent the information to the museum, and the reports I received all confirmed that the white bands with black text on right leg were from a local Danish project. But later I didn't receive information and I decided not to waste my time reporting the birds, and therefore there are several birds that I have no information on, other than my own observations.
THE TABLE:
All entrees except 5 are of Danish banded birds (white band on the right leg with black text, and a metal band on the left leg, except for 5TM which, for unknown reasons, has the bands opposite).
S1723 is a Croatian bird banded in Zagreb on 2023-03-12 as 3cy+
T52J is a Polish bird banded in Szczecin (Stettin) on 2020-01-26 as a 3cy+
TL37 is a Polish bird banded in Gdansk on 2022-02-27 as a 2cy+
TVJE is a Polish bird banded in Warsaw 2021-03-12 as 2cy
T-4 is a Dutch bird (request not sent)
All dates and codes are links to photos of the bird.