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Dark backed Gull central London (1 Viewer)

Chriswilko

Allergic to feathers
In central London today without bins or camera and came upon this Gull on the South Bank. Mantle dark blue grey. Darker than Yellow-leg but touch paler than graelsii. Legs - Pink! Not bubblegum but as per Herring. Light awful and only had phone so pics poor and dont show leg colour at all. Size same as Herring but stockier. Interested in thoughts. Cheers Chris
 

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Nutcracker

Stop Brexit!
Bill? Looks black in this pic. And what looks like a dark eye bar too. If you'd not said it was Herring-size, I'd almost be considering Laughing Gull from this pic. I guess better pics are going to be needed.

Edit: cross-posted, hadn't seen 2nd pic when I posted this. Looks more like a regular graellsii LBB now.
 
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SteveClifton

Well-known member
Allowing for the fact that the photo quality isn't showing the clarity we'd like to see, I can't see anything to exclude a graellsii LBBGull. Blue-grey uppers are spot on and the amount of head streaking looks fine too for a winter bird.

This 7cy has pink legs in December, so I wouldn't worry too much over that: http://www.gull-research.org/lbbgnovdec/axal.html

The dark markings on the bill are probably a sign of immaturity, so likely a sub-adult.

November sub-adult here with similar dark bill: http://www.gull-research.org/lbbgnovdec/adnov015.html
It looks quite pale and short-winged like your bird (primaries still growing)
 
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stevethehydra

Well-known member
I always think of LBBG as distinguished from almost all other large gulls (regardless of what point they are at on the dark/light scale) by having a distinctly brownish-grey, as opposed to bluish-grey, tint to its mantle. This bird looks bluish enough for me to get an instant impression of "not graellsi"... but of course individual variation, lighting and Occam's Razor still point to it being more likely a graellsi than anything else. I wonder though about what would be needed to rule out a Herring x LBB or even (if it was "same [size] as Herring but stockier" Herring x GBB hybrid?
 

SteveClifton

Well-known member
I always think of LBBG as distinguished from almost all other large gulls (regardless of what point they are at on the dark/light scale) by having a distinctly brownish-grey, as opposed to bluish-grey, tint to its mantle. This bird looks bluish enough for me to get an instant impression of "not graellsi"

The reality is a little more complex than that in my experience. Graellsii, especially birds from the west of their range (like here in the UK) are known to be bluer in hue, and obviously lighter in tone than intermedius. Darker still, and reportedly tending towards the reddish/purple end of the spectrum are fuscus, though I have no direct experience of the latter.

Attached are 4 images of adult LBBGulls from northern England.

The first two illustrate birds that I think of as typical of British-breedng graellsii, with an obvious slate blue-tone. They were taken with a phone camera, so apologies for the poor image quality. The phone's white-balance settings might also be responsible for altering the colours a little, but I still feel that they are mostly representative of typical British graellsii.

The third image nicely compares the relatively cold, bluish tones of Black-headed Gulls (which to my eyes are very similar in colour and tone to our local argenteus Herring Gulls); a single sub-adult Yellow-legged Gull (a couple of shades darker than argenteus and distinctly warmer in hue) and several Lesser Black-backed Gulls. I hesitate to label these as typical graellsii as I've often thought that many of the birds that pass through northern England in late summer/autumn are different in tone to our local breeding LBBGs. They are both darker in tone and warmer in hue, and I've often suspected that they might originate from the so-called 'Dutch Integrades' that are a mixed 'hybrid population' of graellsii x intermedius. Either that or they represent a different clinal variation within normal graellsii? Unfortunately I don't have enough ringing recovery data to prove this either way at the moment, though a few that I have traced so far have proved to be from Dutch colonies.

The last image compares what I think is a fairly typical blue-toned graellsii and a bird which is both much darker and warmer in colour (probably intermedius or perhaps even fuscus?). I think the warm evening light is playing a part here, yet both are still clearly different in colour, regardless of how dark they are.
 

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