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-   -   Gull ID, putative Bonaparte's? - Italy, 2018/02/08 (https://www.birdforum.net/showthread.php?t=357046)

Grus91 Friday 9th February 2018 10:11

Gull ID, putative Bonaparte's? - Italy, 2018/02/08
 
4 Attachment(s)
Hi everyone,

yesterday 8th February 2018 i saw a strange gull over the rubbish dump in Gorla Maggiore, Varese, Italy.
It was circling along with tens Black-headed gulls, CG and YLG. The difference of the underwing pattern was immediately visible, giving an overall pale appearence of the underparts of this bird.
When i decided to took some pics, the group of the gulls glided further, so i tried to make some "group photo", hoping that it was in them. Fortunately i got it.
It hadn't the typical pattern of the BHG with an evident black area of the inner primaries, but this area appeared white/greyish. You can compare different pattern from the photos below, where BG(?) and BHG are in the same light condition and in the same position. (Clarification: the dark underwings and underparts are affected by shades in all gulls in the photo). I immediately thought about a BONAPARTE'S GULL.
About size, i was too concentrated about the underwing pattern, so i didin't focus a lot this kind of difference. It seemed to be not so different from BHG, maybe a little bit smaller, but few cms, so i'm not completely sure. Anyway, we know there's sometimes few difference between a small BHG and a normal-size BG (you can find lot of images on the web).
Finally, the bird appeared as a 2cy, with dark tail band and some signs of immaturity on the upperparts.

Sorry for the poor pics, but the all white sky and distance were not the best for good photos.

I hope to know American birder's opinion.
Thanks in advance

Luca

P.s. In the photos the translations are: ('Comuni/Comune'-> Black-Headed Gulls, 'Gavina'->Common Gull, 'Bonaparte'->Bonaparte's Gull).

CARERY Friday 9th February 2018 10:26

Can't recognise much on your photos sorry. Anyway, I would expect a more obvious difference in size, Bonaparte's being clearly smaller.

Steve Arlow Friday 9th February 2018 11:43

Maybe a 2nd winter Black-headed Gull, not a Bonaparte's Gull. Bonaparte's Gull would have pale/whitish undersides to the outer primaries in all plumages, Black-headed Gull has dusky outer primaries. Bonepartes appear smaller than a BHGull, about halfway between a BHGull and a Little Gulls.

Grus91 Friday 9th February 2018 12:23

I don't agree at all about size. Sometimes you can see an huge difference in dimension like BHG versus Little gull, but other times they are very similar (as i said in the original message). However, I'm not completely sure if they were on the same level.
Anyway, have a look at these photos:

http://www.chirpsandcheeps.com/image...8_IMG_0560.jpg

https://1.bp.blogspot.com/-oXbfvIK8O...2BDPF_5756.jpg

https://3.bp.blogspot.com/-L0qwDe1G9...BGull%252B.jpg

http://www.ofo.ca/ofo-photos/7blackheadedtt.jpg

http://www.ridibundus.gull-research....ST178394-1.jpg

Look at the Bonaparte's in the background (out of focus)
https://birdingfaroes.files.wordpres...es-gull-b4.jpg

Look at this 2cy BHG, you can see that at the base of primaries the typical pattern is already present as in an adult bird:
http://i1.wp.com/bucksbirdclub.co.uk...-head-1200.jpg

And so on (see the third last photo):
http://radioactiverobins.com/archive...-bonaparte.htm

About the outer primaries, i saw that 2cy BG has less obvoius pale/whitish undersides to outer primaries, appearing greyer rather than bright white as in adult birds.
I also think that the grey you see on the outer primaries is mainly affected by harsh light condition.

Nutcracker Friday 9th February 2018 21:37

Mystery bird has same size bill as BHGulls, which also counts against Bony's.

Grus91 Friday 9th February 2018 22:06

Can you really see that difference on this poor photos?
Furthermore from literature:

LENGHT OF THE BILL - Means range [mm]

Bonaparte's Gull: from 28.1 to 29.9
Black-headed Gull: from 30.6 to 33.6

I think it's not a diagnostic way to rule out Bony's.
Anyway if you look at the 4th photo, you can note some little differences in bill lenght between Mistery and rightmost BHG

Bye
Luca

Rotherbirder Saturday 10th February 2018 18:37

Luca,
You're obviously convinced it's a Bonapartes so this won't make one iota of difference but, in my opinion - FWIW - it's a Black-headed!

RB

Grus91 Saturday 10th February 2018 19:03

Hi RB,
i'm not absolutely convinced that it's a Bonaparte's.
If I had been sure, I would not have asked about it on this forum.
Till now i read only impressions at first sight, not an analysis about the possibility that it could not be an usual BHG but something else.
I need answers, why a 2cy BHG should show the carachters of my mistery bird?
Why can you find some photos of Bony's with a similar pattern of the underwing in similar light on the Ebird gallery?

Grus91 Saturday 10th February 2018 21:44

Anyway, thanks to all for the opinions. I'll try to come back on the site.
Bye, nice birding

jogresh Saturday 10th February 2018 22:10

Do Bonapartes frequent rubbish dumps in North America? I've always thought of them as more of a purely aquatic gull than BHGs. Almost all of the ones i've seen in the U.S. have been over water (or on the shore).

andyadcock Saturday 10th February 2018 22:13

Quote:

Originally Posted by jogresh (Post 3676940)
Do Bonapartes frequent rubbish dumps in North America? I've always thought of them as more of a purely aquatic gull than BHGs. Almost all of the ones i've seen in the U.S. have been over water (or on the shore).

Most often on freshwater lakes I think, how many UK records have been associated with rubbish dumps?

How many records in Italy?



A

Grus91 Saturday 10th February 2018 22:48

There aren't sightings in Italy for this species yet

Grus91 Saturday 10th February 2018 23:09

It seems that this species seldom scavanges on rubbish dumps.

andyadcock Sunday 11th February 2018 09:59

Quote:

Originally Posted by Grus91 (Post 3676958)
It seems that this species seldom scavanges on rubbish dumps.

I think it's highly unlikely to be Bonaparte's and even if it were, there is little to support the ID from these shots. You'd need much, much better than this to get a national first accepted.

If a 'Boney's' was to turn up in Italy, it would probably be on one of the lakes.


A

balex78 Sunday 11th February 2018 10:06

Ciao Luca. Purtroppo la documentazione non sufficiente per confermare una prima italiana. Da queste foto non c' nulla che possa ecludere con certezza un comune. Le proporzioni sembrano anche le stesse degli altri comuni di fianco. Saluti, Alex Boldrini

MTem Sunday 11th February 2018 13:53

Having been fortunate enough to find a first year Bonaparte's on Harris last Sept with Steve Duffield, and tracked down the regular adult visitor to Oare marshes last August I would agree that size is what first struck me in both cases, with both being surrounded by BHG's. The other features mentioned above then came into play.

I agree I cannot see enough of those features here to even put this in the probable group, personally I would not rate it possible on the basis of these images - but field impressions are worth a hundred photos, so no issue with the posting as clearly the OP saw something to draw his eye.

As an aside I used Google translate on Alex's last post (I can do English and French, but not Italian...)

Hi Luca. Unfortunately, the documentation is not sufficient to confirm an Italian first. From these photos there is nothing that can eclipse with certainty a municipality. The proportions also seem the same as the other towns next door. Greetings, Alex Boldrini

Love it .... but I think the gist is that Alex agrees!

:)

Nutcracker Sunday 11th February 2018 14:22

Quote:

Originally Posted by MTem (Post 3677174)
As an aside I used Google translate on Alex's last post (I can do English and French, but not Italian...)

Hi Luca. Unfortunately, the documentation is not sufficient to confirm an Italian first. From these photos there is nothing that can eclipse with certainty a municipality. The proportions also seem the same as the other towns next door. Greetings, Alex Boldrini

Love it .... but I think the gist is that Alex agrees!

:)

Comune / comuni = Common [i.e., abundant, as in Black-headed], but also Commune/Municipality/Town 3:-)

smiths Monday 12th February 2018 16:59

Hello Luca,

it should be noted that on that 'radioactiverobins.com' website that you refer to,
only photos 14-16 (taken in Churchill, Canada) show Bonaparte's Gulls.
The other photos all show Black-headed Gulls.

Your bird seems to have pale underwings indeed, but it also seems to have little black on the primary tips.
Perhaps something like this should be kept in mind then:
https://waarnemingen.be/foto/view/12105383
(hybrid Black-headed x Mediterranean Gull)


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