Date: 2/1/18 11:39 pm
From: Robert O'Brien <baro...>
Subject: [obol] Re: Armchair Gulling--Sauvie Is. Pellet Plant 1993 redux #2e
And also comments by Lars.

As Phil Pickering commented awhile back, the bill of Slaty-backed Gull
is highly variable. The north Pacific Coastline is close to continuous from
Yaquina Head to Hokkaido and the Glaucous-winged Gull breeds across that
entire arc. We know beyond a doubt that G-wings routinely hybridize with
Western Gulls, Herring Gulls, and Glaucous Gulls on this side of the Bering
Strait. There's no reason to not think they are doing the same with
Slaty-backed
and Vega (the Far Eastern Herring Gull that sometimes is elevated to
species)
on the otherside. OR HAVE DONE SO IN THE PAST. I'm pretty sure Slaty-backs
have been nesting on the west coast of Alaska for awhile. The smaller the
numbers the greater the chance of hybridization.
The first record of Lesser Black-backed Gull nesting in North America
was not
on the Atlantic, but in se Alaska where one mated with a Herring Gull. LBB
Gulls
now regularly mate with Herring Gulls on the Appledore Islands of New
Hampshire.

On Thu, Feb 1, 2018 at 11:36 PM, Robert O'Brien <baro...> wrote:

> Here are Phil Pickering's comments. Being who he is and where he is, he
> looks at a lot of gulls.
> ===================================================
> Hi Bob,
>
> The flanking bird is more than large enough for
> an Olympic. Note the lack of rear attenuation
> and very short primary projection + beady-looking
> eye. The bill also seems pretty substantial if you look
> at it in proportion to the eye.
>
> Cheers, Phil
> ==================================================
> And there is a story behind this. Before sending my comments on
> the three images in the post, I went to another computer and looked
> again at the original perched bird photo that I had cropped. Uh oh,
> I said the presence of another background bird, which I had cropped out.
> Now, by comparison the true (fairly large) size of the other gulls is
> apparent.
> I had somehow assumed they were small, mainly by the size of the
> bill on the left image. I was glad I had waited to send the post
> because now I could edit my interpretation. But going back to the original
> computer I had indeed already clicked 'send'. Oh 'darn' what should
> I do now? Sending an update would only complicate things so I
> decided to wait and see what would happen, nothing bad I hoped.
> Well, Phil obviously had no problems with the original photo showing
> a hybrid, large, gull that I had dismissed based on size.
>
> So, the lesson (to me) is don't study (or photograph) problem
> gulls in isolation. Comparison of size, darkness/color/hue with
> several 'known' gulls is a big help. Attached is the photo I
> should have sent. Once you see the smaller gull in the background
> the subject gulls appear larger (which they are) in comparison,
> as Phil says, even without the smaller gull.
>
> Bob OBrien
>
>
>
>
> On Thu, Feb 1, 2018 at 1:33 AM, Robert O'Brien <baro...> wrote:
>
>> Well, no comments on the last few gulls which seem pretty unambiguous
>> Slaty-backs to me, although there is wide variation between them in
>> many aspects. I'm hoping for some comments on this one though,
>> which stretches their variation even more.
>>
>> Starting with the bill (especially the left-most flight shot)--looks a
>> lot like a Thayer's Gull to me.
>> The bill & bird size seem about right, but the mantle/back sure isn't.
>> The mantle is light compared
>> to the previous SBGUs and note the contrast with the primary tips.
>> Especially note
>> the difference in shade/darkness of the mantle/wings in the left image
>> vs. the
>> other two (these are all the same bird). This is a lighting effect.
>> Not sure at this point but the left and right images may have been taken
>> on different days.
>> The dark feathering around the eye says Slaty-back in all 3 images.
>> and you can slightly make out the dull white eye hiding in there. Also
>> the dark
>> markings a the base of the neck are consistent with other SBGUs posted
>> previously. This is an adult bird.
>>
>> And what about the gull behind the perched Slaty-back. This could be a
>> California Gull, but the primaries tips aren't nearly dark enough. It
>> could be
>> a Western/Glaucous-winged by the wingtips, but both the bird and the bill
>> are too dainty.
>>
>> I'm igoing to go with a very small, dainty Slaty-back for the 3 images.
>> One could delve into SGBUxVega Herrring Gull, but that might be
>> stretching it too far,
>> and won't account for the small size anyway and is likely too
>> dark-mantled,
>> unless it could be a back-cross with SBGU. Things can get ugly.
>>
>> Any ideas out there?
>>
>> Bob OBrien
>>
>> I'm holding off myself on viewing the Japanese SBGU web photos mentioned
>> by Shawneen and Phil
>> for now, trying to relive this epic event of 25 years ago. Eventually I
>> will.
>>
>
>

 
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