Two Puzzling Gulls (1 Viewer)

Dear all,
I've seen both these gulls recently and, for me at least, both are puzzling in their own ways:

The 1st winter gull appears to be one of the 'glaucous x herring gull hybrid' types which I personally haven't seen outside western Ireland (at Killybegs in two successive winters). I watched it for twenty minutes before it became lost to view amongst a mass of Herring Gulls. It was very aggressive and was pursuing the other Herring Gulls to rob them of any food they had. The gull was about the size of a Herring Gull or a little larger. What really struck me, and what I don't recall seeing on a Herring x Glaucous hybrid before was the underwing pattern (pity the bird's body was hidden from sight behind a bank of sand!). I played back my video I'd shot and watched the scene with the wings flicked upwards in slow motion - to my surprise the flight feathers on the underwings are clean white contrasting with the brown axillaries. If anyone has seen anything like this before, or can add anything to this bird's identification/parentage, I'd like to hear from you.

The near-adult/adult gull may be less of a puzzle but I've been in two minds ever since I saw it. I'm hoping the forum can solve this one for me.

If further photos of any features on either bird are required, please let me know.

Thanks,

Lancey

Ist one has an element of lesser-black backed gull with herring (as opposed to glaucous)

2nd one looks like a ring-billed gull.

I'm no expert on this and will be corrected very quickly I'm sure - just thought I'd give my 2 cents worth.

Hi Lancey,

The 1st winter bird doesn't show any Glaucous features from what I can see on the photograph, I would be surprised if one of its parents had been a Glaucous, the most obvious feature is the all black, small, bill show on the bird, and the dark mantle and seemingly dark brown/black primaries.

The adult bird looks like a Common Gull to me. Note the 2 outermost primaries, both show large white mirrors. The black bill band doesn't seem prominent enough on the upper mandible. Mantle looks dark, but I wouldn't comment on this from looking at a photo. Head shape is interesting to invite a closer look at first glance. Lancey, what colour was the eye in the field? I can't tell from the photograph

all the best

Have to agree with James about the adult, the bill is just the wrong shape for delawarensis (Ring-billed) and the eye looks too dark. Also the tertial crescent (the patch of white just before the black primaries) is too wide. This is Larus canus (the Mew or Common Gull).

David

I do not think the second bird is a Ring-billed Gull. The mantle is too dark, too much white in the primaries and the white tertial crescent looks too extensive. I would call this a Common Gull.

ATB
Tristan

dunno...

look like a Herring and a Common to me

I think head shape and bill shape are ring-billed (both too big for common).

I do agree, however, that the white markings on the tail are more like common gull.

There is something disctinctly odd about the Herring Gull-type* though I am far too gull phobic to know where to start, the second is 100% Common Gull though.

*Can't see any Glauc structure.... could be persuaded of odd genes though... not up on Thayer's-type features

Must admit the photos of the bird standing do just seem to be Herring Gull. The underwing shot looks interesting however but I can't decide if this is just an effect of the light? Suggest you post it on

http://groups.yahoo.com/group/birdinggulls/

you'll get plenty of expert help there.

As for the second bird definately seems just to be a Common Gull.

JP

Hi there,
The first bird seems more like a northern argentatus on plumage, but the underwing pattern looks distinctly odd. That said, I seem to recall a paper on argentatus that suggested that they can show such pale remiges below....
The second gull appears to be a Common Gull, on wingtip pattern, mantle shade, bill structure etc.
Harry

Tim100 said:

I think head shape and bill shape are ring-billed (both too big for common).

Click to expand...

Tim100 said:

I do agree, however, that the white markings on the tail are more like common gull.

Click to expand...

Hi Tim



I can see what you are saying about the head shape of this bird as Ring-billed Gull always had a 'sterner' look than Common Gull. However the head shape shown by this bird is a little miss-leading, probably due to the stance of the gull. The bill is certainly not right for Ring-billed Gull as sides are quite parallel (Ring-billed Gull show a much steeper gony' angle giving a more 'swollen-tipped' appearance.).



The bill structure, mantle colour (far too dark for Ring-billed Gull), extensiveness of white tertial crescent (Ring-billed Gull show a very reduced tertial crescent) and amount of white on primaries rule out Ring-billed Gull in my opinion. Also (admittedly not easy to make out from the image) the eye looks dark (Ring-billed Gulls of this age show a yellow iris).



ATB

Tristan

Thanks for the extensive gull information once again Tristan.

I must admit I do rely on my Hamlyn bird book (not always the best way I know) and the picture does fit certain elements of both RBG and CG.

I guess experience of watching them in real life is probably te best way.

Tim

very true Tris

the head looks superficially Ring-billed - this must be due to the bird's posture and activity at the time. Always best to approach pix like this with a shovelful of salt.

atb
Tim

Gull Identification

Dear all,
Thanks for your contributions so far. I'm happy the adult gull is a Common Gull but the immature I'm as yet undecided.

Admittedly the gull has more Herring Gull than Glaucous Gull about it, but so have the Glaucous x Herring Gull hybrids that have been 'multi-observer records' in Ireland. I presume that a hybrid can look more like one parent than the other, so the offspring could appear more Herring Gull than Glaucous Gull.

What bothers me is the underwing pattern. I'm confident that the light was suitable to realistic rendering of white plumage - something that cannot be said of a bright day. Indeed, the white of accompanying gulls (such as the Common Gull) bear testimony to the overcast conditions I (thankfully) had for filming. I have included a videograb of the wing raised that shows every primary and secondary feather to be unmarked, transluscent white. I don't accept partial albinism nor leucisism would account for these affects purely because the underwing pattern is so symmetrical.

The plumage of the bird is very much one tone of colour without contrast that adds to the oddity factor. Something else I've noticed is that the bird has what appears to be dark bands on each leg just above the foot, as if it's been ringed/banded in some way. It isn't a photographic distortion either, it has them when it emerges from a rock pool and still has them later on when walking on the sand in a different environment altogether.

The reference to a Thayer's-type gull was coincidental since the plainness of the plumage did make that cross my mind too once I'd seen the video. However, the underwing pattern (for one thing) would discount that possibility. 1w Kumlien's Gull crossed my mind too but the bird doesn't resemble an Iceland Gull so that can be discounted too.

In a nutshell, I can't easily account for what I've seen but I' am glad I had the ability to video it and share it.

Regards,
Lancey