cr-gull green XLEN

[alfosse]

German gull green XLEN seen in Western France on 11.12.14.
Rather stocky, dark underside, shortish bill…
Mantle, scapulars, coverts seem to fit Caspian.
Pure Caspian or not?





Video:
http://youtu.be/E2giDjekVUU

[alfosse]

Not! Actually ringed on 3.6.14 at Gräbendorfer See (DE) as Larus michahellis…
See life-history on http://baguage.lpo-anjou.org/XLEN
(Thanks to Ronald Klein, Roland-Jan Buijs and Jean-Michel Sauvage.)

[lou bertalan]

salut alain,

personally i don't think this is a (pure) michahellis. bill shape, small eye, plain coverts with diffuse pale fringes and esp. scap pattern with black markings in uppers concentrated around shaft with a thin subterminal bar: all smells at least to have some cachinnans blood. it would be nice to have more detailed info about the circumstances of ringing for this bird.

lou

[alfosse]

personally i don't think this is a (pure) michahellis

Yes I do agree. When I first saw the bird I couldn't make up my mind. On the pictures, I found some discrepancies: Caspian-like upperparts but head, bill, underparts not usual for that species…
When Ronald said it was ringed as a micha, I was a bit puzzled: a micha probably would have a whiter head…

[Ronald Klein]

A determination as chick mostly means nothing in these mixing colonies with hybridization. Best way is their identification later.

[Emmanuel]

A determination as chick mostly means nothing in these mixing colonies with hybridization. Best way is their identification later.

Hi friends,
Ronald, is Reddern nearly pure, because "founded by Caspians in the last 5 years", or strongly "mixed with hybridization"?

If mixing: + few michahellis, or even argentatus? (as in Sedlitz... and despite absence of HG in near S-POL?!)

Last, do you know why XLEN was said "michahellis" by ringer, while birds ringed in Reddern are usually said "Herring Gull (Group) (Larus argent./cachin./michah.)"?...

Good evening,
Emmanuel

[Ronald Klein]

All colonies in Lausitz are +/- mixed.
Gräbendorfer See (Reddern) is dominated by Caspians with some HG, Sedlitz mixed HG + CG.
YLG is in minority, >10%.
Many gulls in the colonies are hybrids, because they interbreed since 20 years.
But the number of pure CG is increasing.

[alfosse]

Again seen on 23, 26 and 30 Dec, still some doubts about its identity. New pictures on http://www.digimages.info/goeleu/goeleu.htm#XLEN. Updated life-history on http://baguage.lpo-anjou.org/XLEN