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Some regulars at the Barneveld waste dump yesterday:

Black JZZ7:




Red H.871:








Green XTAV was also still present, which I've ID'ed as a Yellow-legged, based on the scapular moult and light inner primaries.






I've also been able to read part of the ring: EA xxx3609 which confirms it as a German gull. Ronald informed me that it wasn't one of his but that it's a gull from the mixed colony in Lausitz.
So the project ID is still open, does anyone have any further suggestions who to contact?

EA rings are also used in France...

Theo Muusse

Thanks Theo, you are right of course. I was making the link to Germany because of the green ring.
I have reported the rings on bto.org now, maybe that will resolve the issue.

And again Maarten, you've made nice pics at my local patch.

XTAV may also turn out to be a cach..

Theo

Theo Muusse wrote:XTAV may also turn out to be a cach..

Theo

..or even an argentatus x cachinnans...there´s something of a mix over it, inner primaries facial expression.

JanJ

Just received the life list of XTAV. It was ringed as pullus as a pure Caspian near Sedlitz, Oberspreewald-Lausitz, Brandenburg, Germany. On the recovery data that has been changed (in my case at least) to Herring Gull (group).

Ruud Altenburg wrote:Just received the life list of XTAV. It was ringed as pullus as a pure Caspian near Sedlitz, Oberspreewald-Lausitz, Brandenburg, Germany. On the recovery data that has been changed (in my case at least) to Herring Gull (group).

hi ruud,

why do you think it is not a pure cachinnans? in my eyes there's little to suggest argentatus influence. as far as i know the colonies in the lausitz are mixed but cachi has become by far the most numerous sp. and i guess the ringers would have checked the parents?

lou

A lot of ringers have no clue about the parents of the chicks they are ringing. This is possible only if you mark nests and carefully follow what's happening. Even then you cannot exclude the possibility of a naughty neighbour

I've personally labelled XTAV as a hybrid because in the field it looked quite different from the other Caspians present, e.g. it was much darker (initially it was reported as both YLG and LBBG!) and the greater covert pattern is different from the norm. When seeing these pictures again structurally there isn't much wrong with pure Caspian.

By chance I photographed a putative hybrid today, I'll upload some images tonight.

Here's the 1cy hybrid cachinnans x argentatus at IJburg, Amsterdam today.