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Mystery Gull? (1 Viewer)

jpoyner

Well-known member
Scotland
Hi,

This gull photographed in the north of Scotland has been the cause of some debate. I won't suggest anything. The mantle colour which is difficult to judge is paler than nearby LBB gulls but obviously darker than Herring.
Thoughts from any gull buffs?

JP
 
This One !!!

Mmmmmmmmm for some reason the photo didn't attach to the message. I'll try again. Help.
 

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The mantle is fine for michahellis, but the pink leg is wrong, and the head shape doesn't strike me as right either. The lower pic has something of the cachinnans look about it, but I'm not familiar enough with that to say for sure.

Michael
 
I agree...all seems good for a YL Gull michahellis which is what I initially thought it was. (Very rare in Moray where it was photographed). But looking at the photos the head and bill seem a bit odd and like you say the leg colour too. I wondered if perhaps leg colour didn't develop so strong in injured or vagrant birds?
It was suggested that it might be a hybrid...however it was with a second, almost identical bird which seems to make this theory unlikely I think. (Unfortunately we didn't get good photos of this bird).

J Poyner
 
jpoyner said:
I agree...all seems good for a YL Gull michahellis which is what I initially thought it was. (Very rare in Moray where it was photographed). But looking at the photos the head and bill seem a bit odd and like you say the leg colour too. I wondered if perhaps leg colour didn't develop so strong in injured or vagrant birds?

Sorry, no idea if health can affect bare parts colour in gulls!

jpoyner said:
It was suggested that it might be a hybrid...however it was with a second, almost identical bird which seems to make this theory unlikely I think. (Unfortunately we didn't get good photos of this bird).

If they were siblings from the same local brood, no problem (or from successive broods from the same pair, as gulls often mate for life). LBB x Herring is a real possibility, unfortunately not one I'm familiar with.

Let's see what Spud says!

Michael
 
Depending on the time of year the lack of head streaking could be a pro-YLG feature. On balance I would go for YLG anyway, as I have seen the odd bird generally thought to be this species with pink legs and everything else seems fine.

Stephen.
 
It doesn´t look like a Caspian. The mantle looks too dark, the eye is not dark enough and the head and bill shape don´t look right either.

The first pic apparently shows some immature lower tertials. The other pic certainly shows dark primary coverts. Probably a 4cy (3rd summer) bird. This could explain the pinkish legs if it´s a YL Gull. But I still think it should have a yellowish tinge at this age.

I don´t know.

Im putting 50p on argentatus or YL Gull michahellis or hybrid!
 
There's also a bit of black on the bill (more evidence of immaturity), but it is otherwise rather shockingly bright yellow, a good feature for michahellis YLG. But I still think the head & bill shape isn't really right for that.

Michael
 
I doubt that this bird is identifiable.

Superficially it certainly looks like a michahellis Yellow-legged Gull (there is really nothing to suggest Caspian) and if seen in the Mediterranean or even southern England would quickly, but perhaps wrongly, be dismissed as such. In Scotland however it is a different story as this species is still a notable rarity there and greater caution is required, especially as the possibility of a lookalike Herring X Lesser Black-Back exists (and other hybrid options are also possible).

In a Scottish context any odd features therefore take on much greater significance and there is no doubt that the leg colour is odd. Yellow-legged Gulls tend to develop yellow legs relatively early in life and are far less likely than Lesser-black backs to show pink legs at this age. The fact that the bill is so bright suggests that this individual has no physiological problems affecting bare part colours and if it were a Yellow-legged it would really be expected to have a least some obvious yellow tones in the legs. The jizz of the bird does not particularly recall Yellow-legged Gull to me but that is a fairly subjective call and some female Yellow-legged Gulls can probably look like this, at least in a short series of still images.

I've no idea how common hybrids are, though they are perhaps commoner than is often realised, but I can see no reason why a hybrid should not look like this - several other known hybrids have looked essentially similar and some have even shown yellow legs.

Sub-adult large gulls are more difficult to identify than first-years or adults as there are very few, if any, conclusive features to go on due to individual variations in the way birds develop. Even with a good view of the open wing I doubt any real progress could be made. The Atlantic forms of Yellow-legged are basically similar to michahellis in all significant regards and can't be used to explain away the odd seeming features.

The fact that the primary coverts are tipped white suggests that the bird cannot be a pale mantled lesser Black-back and the mantle is too dark for even the darkest argentatus Herring Gull but beyond such conclusions not much can be said, although I'd suggest that the grey tone of the mantle doesn't seem to have the very neutral ash-grey quality of a typical michahellis.

DNA analysis or a colour ring (if it once had one!) would probably be the only way to identify this particular bird beyond reasonable doubt.

Spud
 
logos said:

.

The fact that the primary coverts are tipped white suggests that the bird cannot be a pale mantled lesser Black-back
Spud

Hi,

Thanks for the excellent reply. You are the first to make this observation in ruling out LBB which is interesting. Was just trying to check what the primary coverts should look like in LBB, probably simpler if I ask you!

J Poyner.
 
Hi John,

On immature LBBG (I assume your bird is a 3rd-summer and probably taken in May or June judging by the appearance of the birds around it) the primary covert tips are either dark grey and non-contrasting or, at most, finer and duller than on your bird. the strikng white tips on your bird are more in keeping with the pattern shown by Herring or Yellow-legged. There are exceptions to almost every rule of course but this would be a very exceptional pattern in a Lesser.

Spud
 
Have a look at this Herring Gull which I digiscoped (from a few 100yds) on Sept 30th.

A nearby graellsii was noticeably darker from all angles.

The weather was overcast but not particularly dull.
 

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Hi

I would say that this bird is a michahellis, or very possibly a hybrid. The head and bill shape are perfect for a Yellow-legged Gull and they can have flesh-coloured legs, especially in immature plumages.

I'm confident it is not a Caspian Gull.

Best wishes
Dawn Balmer
 
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