4 birds: pure Caspians or...?!

[Emmanuel]

Hi all,
In western France, Caspians are not really common yet. Every data remains suspect, even if the bird is ringed.
A few authorities may cut short... but disagree together as well!
Some birders have their own experience - often fragmentary.
Consequently, mentions relate generally to ringed birds, yellow P... or green X..., with anyway doubts about genetic purity.
Thus, to be approved as a Caspian, a gull needs to be an 'ultimate Caspian'.

I take the liberty of submitting to your assessment some pictures of 4 birds, with no further talk but dates and locations:
- One juvenile without ring: Chatillon-en-Vendelais (35-F), 18/08/2012 (1 photomontage).
- PNKA: Houlgate (14-F), 19/09/2014 (1 photo).
- XWAZ: Port-en-Bessin (14-F), 4/05/2012 (4 photos).
- A very distant one without ring: Careil (35-F), 3/09/2014 (2 photomontages).

Thanks for your opinions.
Regards,
Emmanuel

[adriaens]

The 4th set of photos are way too poor, but the other three birds look like normal Caspian Gulls to me.

As a remarkable coincidence, I came across PNKA myself today!
It was in the harbour of Oostende, Belgium:
http://waarnemingen.be/waarneming/view/89245952
The flight shots reveal a normal pattern for 2w Caspian Gull, including a small white mirror on outermost primary.
The ringing data will give us more information soon.

[lou bertalan]

The 4th set of photos are way too poor, but the other three birds look like normal Caspian Gulls to me.

As a remarkable coincidence, I came across PNKA myself today!
It was in the harbour of Oostende, Belgium:
http://waarnemingen.be/waarneming/view/89245952
The flight shots reveal a normal pattern for 2w Caspian Gull, including a small white mirror on outermost primary.
The ringing data will give us more information soon.

hi,

i mostly agree with peter, but green XWAZ to me doesn't look like a pure caspian (ringed in eastern germany?). it shares features of cachinnans and michahellis and might be such a hybrid: tail pattern with a tapering black band and spots instead of narrow bands basal from the tail band look a lot like micha as well as the stubby bill. even though this hybrid combination seems to be rare.

[adriaens]

Perhaps we will learn more from the ringing data, but in any case such a tail pattern is well within the variation of Caspian Gull. So is the bill shape (which can be a lot stubbier, by the way).
I have attached 4 different 1w Caspian Gulls from Georgia (January 2014), showing tail pattern. Note also variation in bill shape.

CaspianGull_1c_Georgia_20140131_387.JPG (890.43KiB)Viewed 24178 times

CaspianGull_1c_Georgia_20140130_269.JPG (648.66KiB)Viewed 24178 times

CaspianGull_1c_Georgia_20140127_142.JPG (746.48KiB)Viewed 24178 times

CaspianGull_1c_Georgia_20140126_038.JPG (774.92KiB)Viewed 24178 times

[Emmanuel]

Thanks to Peter & Lou!

I agree with you too: both first birds look very OK; my 4th one was definitely too far... (alas, with such a reminding jizz!)

XWAZ: details lead to consider (or not exclude) a possible hybrid - but not arg x cach ?!...
That's why we were interested in your opinions - even if Normand larophiles already found it suitable as a Caspian.

PNKA: remarkable coincidence (& luck) indeed!
4 weeks between Houlgate and Oostende - just the time we speak about it!

About 'learning more from ringing data': don't expect anything precise...
PNKA was of course ringed on 24.05.2013 in Kozielno; given species is 'Caspian Gull colony (Larus cachinnans kolonia)'.
XWAZ on 07.06.2011 in Sedlitz (Oberspreewald-Lausitz, Brandenburg); given species is 'Herring Gull (Group) (Larus argent./cachin./michah.)'.

Regards,
Emmanuel

[adriaens]

Still... Kozielno is in the very south of Poland, close to the Czech border.
If you check the breeding distribution of large gulls in Poland (see http://www.academia.edu/1056046/Neubaue ... _127_11-22), the colonies in the south predominantly consist of Caspian Gulls. The hybrid zone is mainly in the middle of the country.

[lou bertalan]

but sedlitz is...hybridization seems to become more extensive the larger the colonies get.

[Ronald Klein]

In the Lausitz are 2 large colonies with ringing-activity. Gräbendorfer See (Reddern) and Sedlitzer See. Gräbendorf is the younger one, founded by Caspians in the last 5 years. Sedlitz exist since over 20 years and is clearly mixed, also with some YLG as third component. Interbreeding is common. Unfortunally it is not possible to identify the parents of the ringed chicks.

[Emmanuel]

Many thanks again to Peter, Lou & Ronald for your opinions and infos.
Details about Lausitz colonies are very suitable.

14 different ringed Caspians have been read in Normandy (around Caen) since 3 years: 9 ringed in Poland, 7 Kozielno + 2 Jankowice; and 5 in Germany, 4 Reddern + 1 Sedlitz (XWAZ).
XWAZ could be a good Caspian, but this bird is precisely the one whose purity remains questioned - and already was before your infos about Sedlitz vs Reddern.
It could be a 50-50% hybrid, but much more probably a mix of e.g. X/64 Caspian, Y/64 Herring and Z/64 YLG, with X + Y + Z = 64...
And if X >> Y + Z (as probable), then it has to be considered as a kind of good Caspian indeed.

Some un-ringed birds now - all looking very whitish, but... I'll give my opinion afterwards.
Thanks for yours.

Regards,
Emmanuel

[Emmanuel]

I put another kind of game, if you don't mind:
http://seawatch.free.fr/bagues/pontique ... tivaux.jpg

The question is:
Of these 11 summer juveniles, only one is regarded by some laridologists as a non-Caspian: which one?!

Try & enjoy!
Emmanuel