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Larus argentatus - cachinnans? (1 Viewer)

Dobrý den,

můžu poprosit o Váš názor s určením racka (07.11.2020)?

Děkuji :)
 

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Deb Burhinus

Used to be well known! 😎
Europe
Vítejte!

Welcome to Birdforum Jaroslav!

I agree this looks like a 2cy cachinnans - it is better to wait for more opinions though (I have no expertise in gulls!)
 

Alexander Stöhr

Well-known member
Hello,
welcome to birdforum from me, too.

I asume that this Gull was photographed recently in the Czech Republic? Then its allways good to remember, that there are mixed colonies in not so far distance (for a Gull), resulting in hybrids and intogration from different species (and I hope for the experts to learn from them, like Deb).

Are all pictures of the same bird? I have the feeling, that two different birds are shown.

I agree with Deb, picture 1 - 3 looks like a Caspian Gull to me. It looks like, what many gulls look like in NE-Germany and W-Poland, where Caspian Gulls and Caspian x Herring Gulls are abundant. So I hope for expert opinions if this bird can be considered as a "pure Caspian Gull" in this area or better named "Larus polonicus". Thats a name I heard from experts tackling this situation (or avoid it?)
Such a large bill is within variation for Caspian Gull, because it has the right parallel shape. For another example look here: https://www.dropbox.com/s/fyf7l88mxohzmq2/DSC08096.JPG?dl=0 (10.02.2014, Forggensee S-Germany)
Washed dark bands from eye to neck (ghosting Ichthyaetus ichthyaetus) are present on many "Caspian Gulls" in NE-Germany: https://www.dropbox.com/s/kj8fojlehhqopw5/steppenmöwe 19 31.8.13.jpg?dl=0 (Ahlbeck, NE-Germany, 31.08.2013)
(are such strikingly barred greater coverts within variation for Caspian Gull or its better to call them "Larus polonicus?)


But: your bird in picture 4 looks like a Yellow-legged Gull Larus michahellis :
-square head with angular rear and broad bill with evident gonys angle (even reminisend of a small billed Larus marinus)
-dark washed mask behind eye
-dark wash to rear neck lacking neat streaking of Caspian Gull
-quite uniform dark greater coverts without barring is variation for Larus michahellis

Caveat: although I wouldnt hesitate to ID bird 4 as Larus michahellis when seen in SW-Germany (by bill and head profile and head colouration alone), I have seen a bird that looked like a michahellis to me, but I was corrected by Gull experts that it looks better for a Herring x Caspian Gull hybrid.
 

Deb Burhinus

Used to be well known! 😎
Europe
Can I just say that when I posted this morning there was only ONE image in the OP’s post which is image #1 . Please note the time the OP edited the post. Thank you. ( I don’t have time now to look at all the others.)

Btw Alex, can I please ask you stop referring to me when you write your posts on these ID threads unless you are directly quoting me or addressing me directly. (I am happy to help out on ID threads when I know and have the field experience to do so, but for me, it’s not really a focus of study as it is for you and I really don’t have time to plough through lots of old threads and excessively long analysis or comments as you do! I’m usually working if I’m on the computer during the day so the simpler the better!) Many thanks :t:

ps 1-4 are the same gull so your comments are rather confusing!
 
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SteveClifton

Well-known member
I would call both birds 1cy cachinnans if I found them, based on these views. I don't see anything really in the head pattern, bill colour (or indeed shape), pattern of scapulars (with those plain lower scaps) and relatively plain greater coverts which would lead me to think michahellis. The pattern of the upper scapulars-those few with dark centres and distinctive white fringes are in my experience also very typical of cachinnans.

It's hard to be certain whether all images relate to one or two birds. Large gulls can be real chameleons and can appear very different when viewed in different lighting. Digital cameras can also overstate markings like those we can see on the head and breast/flanks. See the same bird in bright sunlight, or photographed with a different camera, and it/they would very likely present as much more normal Caspian Gulls.
That said, there do appear to be differences in bill colour between pics 1-3 and pic 4. Also the first bird (in pic 1) appears to have moulted some inner wing coverts (greater and medians on one side) so it could be a little more advanced and I suspect is indeed a different bird..

Both birds are 1st calendar years (majority of wing coverts are first generation juvenile feathers, for example). Tertial fringes also are relatively narrow and very worn looking, not to mention the considerable streaking on the head and body which would be wrong for most 2cy cachinnans.

Alexander, I do see the relatively angular head and bill (with gonys angle) and strong ear covert markings in pic 4, so the latter might hint at some mixed genes, but what I think we're finding these days is that a much broader degree of variation can still be found within the 'acceptable cachinnans' population than was previously thought. As this species' range spreads and populations become 'diluted' we are seeing many birds which are less impressive than those perfect examples depicted in many guide books, but they are still acceptable-some more than others!.

Views of under and upper wings might give more clues but I would conclude that both birds are acceptable 1cy cachinnans - with the caveat that bird 4 might even be the same individual? (though I now strongly doubt it) and that if images of under and upper-wings became available, they don't show anything too untoward.
 
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Deb Burhinus

Used to be well known! 😎
Europe
Both birds are 1st calendar years (majority of wing coverts are first generation juvenile feathers, for example). Tertial fringes also are relatively narrow and very worn looking, not to mention the considerable streaking on the head and body which would be wrong for most 2cy cachinnans.
.

I agree the first image is in 1w plumage so depending on when the photo was taken, it is a 1cy/2cy bird.
 

Alexander Stöhr

Well-known member
Sorry Deb,
it wasnt meant as an offense.
Thank you Steve, much helpful to me.

The propable Herring x Yellow-legged Gull is this: https://flic.kr/p/2k6wmFF (Prenzlau NE-Germany 22.10.2018).
I must admit, that I was quite sure that this was indeed an YLG and didnt realized the possibility of an hybrid, this possibilty was mentioned to me by Detlef Gruber and Martin Gottschling. So thank you both!
 
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Deb Burhinus

Used to be well known! 😎
Europe
quite obviously all 4 pics show the same individual, which is a male 1cy caspian gull. i see no sign for a possible hybrid.
A conclusion I came to two weeks ago 😉 - Nutcracker if the date of the exif says is 20 November, that would be impossible for it to be a 1cy as the image was uploaded on 14 November which of course would be a week before the images were taken!
 

Nutcracker

Stop Brexit!
A conclusion I came to two weeks ago 😉 - Nutcracker if the date of the exif says is 20 November, that would be impossible for it to be a 1cy as the image was uploaded on 14 November which of course would be a week before the images were taken!
Strange! Can only assume either he has a time machine, or else the date stamp in the camera is wrong 😜
 

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