Gull for Identification (3 Viewers)

[Lancey]

Dear all,
I saw a gull yesterday that I'd initially believed to be a Little Gull but the sighting was so brief that it flew before I could really get much on it. Luckily it returned an hour later for a minute during which time I managed to get some video of it before it flew off and didn't return.

Today I've looked at the video and the wing pattern with its dark trailing edge looks like the gull was actually a 1st summer Bonaparte's Gull to me. Do the gull enthusiasts amongst us agree?

Regards,
Lancey

 

[London Birder]

trailing edge thickness looks more in line with Black-head to me but I can't open last two pics so...

 

[Lancey]

Gull

London Birder,
The jizz of the bird seemed to me more like a Little Gull. I've reattached the last two photos if it helps.

Lancey

 

[London Birder]

ta Lancey, I'll keep trying, think it's my browser

 

[Lancey]

Gull

Thanks London Birder,
I've just looked at the video again and the bill looks needle-like rather than the slightly drooping look of Black-Headed Gull. This would contribute to the Little Gull jizz I mentioned earlier. The head and wing markings are also black looking rather than the dark brown of Black-Headed Gull. However, I realise that atypically small Black-Headed Gulls do exist so perhaps I have been fooled again?

Lancey

 

[JANJ]

Hi Lancey, long time no see!

It´s not a Little Gull, bill is to long, rather different wing pattern.
Either a Black-headed or Bonaparte´s. But which?
It doe´s give a certain BG impression, rather thin, black looking bill, a little long perhaps. There´s much dark on the outer secondaries (image 2), reaching greater coverts, more like BHG, but inner primaries looks pale. but on the right wing they look darker, like BHG. Also dark parts of wing looks blacker, usually brownish in BHG. Dark on outer primaries and primary coverts with pale inner p-coverts in line with BG. Is that the underwing we see in image 3.
I´ll suggest BG, but do you have some more images Lancey, I´m a cautious devil (or a coward)

http://www.pbase.com/jpkln/bonapartes

JanJ

 

[Lancey]

BG versus BHG!

JanJ,
Thanks for your reply which sums up the issues I've been thinking about regarding this bird. Firstly, if I trust my gut reaction that the gull was a Little Gull when I first saw it then by default it favours BG. I've watched the video on the television and the bill looks black, needle-like and without the shape of BHG. The traling edge to the wing looks black as does the tail band and the head markings.

But, my concerns are:

The pink legs of BG aren't visible (maybe due to the light direction?).
The nape doesn't look grey which BG should show (bleached by the light?).
Is there too much white showing in the folded wing or isn't the wing fully folded (giving an incorrect impression?).

It's tricky because the duration of the observation wasn't long (less than a minute according to my camcorder). It's frustrating!

Do my comments help or hinder you JanJ? I'm afraid, in terms of the video, the photos attached are the best I can get.

Lancey

 

[Lancey]

BG versus BHG

JanJ,
I've attached another photo just in case it helps.

Lancey

 

[Thayeri]

For what it is worth, from someone who sees quite a few Bonaparte's, my initial jizz impression was that the bird was not a Bonie -- too large of bill, and too powerfully built of bird. However, we all know how jizz can mislead with gulls, so on to the details!

Lancey and JanJ are in my opinion quite correct in their concerns about bill length and leg color. Nape is OK for a BG in first summer plumage, and there is something bizzare about the folded primaries, it would be wrong with either species, and I'm going to have to assume slightly unfolded as well.

If I'm understanding right, the theory behind BG is the wing pattern? In my opinion the wing pattern is why the bird is likely a BHG and not a BG. Notice how in two of the photos, the thickness of the trailing band peaks at the inner primaries. The thick trailing edge that London Birder refers to.

Should not be there for Bonaparte, they should be thinner at the inner primaries than the outer primaries.

The other thing to keep in mind is time of year. Wear won't turn a BG's primary edges darker in a thicker pattern. But they will sometimes bleach out the pattern on a BHG, making it look more like a BG. For those who have it, look at plate 638 in Gulls of... (Olsen & Larsson) where it shows a 1st winter BHG in late March that has lost much more of its dark primaries than this bird.

Larus ridibundus for my vote, or the least, a negative for Bonie...

 

[JANJ]

Lancey,
if you look at the inner primaries on the 2cy BG,s in the link which I posted, you´ll se the cleaness, and absence of dark 'lines'. Another character I forgot to mention before is the primary coverts, on BHG the middle ones are white tipped, just the inner on BG.
Regarding the pattern on the nearly folded wing, which looks similar to this:
http://www.pbase.com/jpkln/image/59443599
is also shown by some BHG
The bill is on the long side for BG, more in line with BHG, at least judging by the images

There are some variation in BHG though, some has more dark on outer primaries, check Gulls. The greyish neck, and neck- sides may not always be obvious. Did you by any chance see the underwing Lancey, because that would settle it.

http://www.pbase.com/jpkln/image/59314379

http://www.deanar.btinternet.co.uk/wmgulls/BhG/1Wflight.htm

BHG is the final vote.

JanJ

 

[London Birder]

still can't open ! but see your latest pic Lancey ... well these two chaps are far better gull men than I but I'd certainly lean toward BHG ... interesting you should say about 'runt' BHG's, I know for a fact they exist as I found one sitting on top of a warehouse roof in Kent once (on way back from Stodmarsh I think, near Canterbury)... the little thing even had a dark looking bill but in every other respect was a perfect ad wint BHG!

 

[Edward woodwood]

looks like a BHG too

the wing pattern should clinch it fairly easily in the field

Tim

 

[Lancey]

Bhg

Thanks everyone for your contributions,
It's a pity that the sighting was so brief. Had I seen it for longer I may have been able to get more on it of course. However, I agree that BHG must be the most likely candidate (as it should be given that I saw it in the UK of course!),

Lancey